04 Air Quality

4.1.1.1 The EIA Study Brief for the Trunk Road T2 Project (ESB-203/2009) requires that an air quality impact assessment of the proposed project be undertaken. This air quality assessment has included potential air quality impacts during both the construction and operation phases of the selected alignment. Details of the selected alignment are presented in Section 3.

4.2 Environmental Legislation, Standards and Guidelines

4.2.1 Background

4.2.1.1 The air quality impact assessment criteria shall make reference to the Hong Kong Planning Standards and Guidelines (HKPSG), the Air Pollution Control Ordinance (APCO) (Cap 311), and Annex 4 of the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM).

4.2.2 Environmental Impact Assessment Ordinance (Cap 499)

4.2.2.1 Reference to the EIAO and the associated EIAO-TM has been made for the assessment of air quality impacts. Annexes 4 and 12 of the EIAO-TM set out the criteria and guidelines for evaluating air quality impacts, which requires that f or construction dust impact an hourly averaged Total Suspended Particulates (TSP) concentration of 500mg/m³ shall not be exceeded.

4.2.3 Air Quality Objectives

4.2.3.1 The APCO provides a regulatory framework for controlling air pollutants from a variety of stationary and mobile sources and encompasses a number of Air Quality Objectives (AQOs). Moreover, the Government’s overall policy objectives for air pollution are laid down in Chapter 9 of the Hong Kong Planning Standards and Guidelines (HKPSG) as follows:

· Limit the contamination of the air in Hong Kong, through land use planning and through the enforcement of the APCO, to safeguard the health and well-being of the community; and

· Ensure that the AQOs for 7 common air pollutants are met as soon as possible.

4.2.3.2 The AQOs stipulate concentrations for a range of pollutants namely sulphur dioxide (SO2), total suspended particulates (TSP), respirable suspended particulates (RSP), nitrogen dioxide (NO₂), carbon monoxide (CO), photochemical oxidants (as ozone) and lead (Pb). The AQOs are shown in Table 4.1.

Table 4.1 Hong Kong Air Quality Objectives

Pollutant	Concentration⁽ⁱ⁾ mg/m³ Averaging Time
Pollutant	1 Hour⁽ⁱⁱ⁾	8 Hours⁽ⁱⁱⁱ⁾	24 Hours⁽ⁱⁱⁱ⁾	3 Months^(iv)	1 Year^(iv)
Sulphur Dioxide (SO₂)	800	–	350	–	80
Total Suspended Particulates (TSP)	–	–	260	–	80
Respirable Suspended Particulates (RSP)^(v)	–	–	180	–	55
Nitrogen Dioxide (NO₂)	300	–	150	–	80
Carbon Monoxide (CO)	30,000	10,000	–	–	–
Photochemical Oxidants (as ozone^(vi))	240	–	–	–	–
Lead				1.5

i. Measured at 298K (25°C) and 101.325 kPa (one atmosphere)

ii. Not to be exceeded more than 3 times per year

iii. Not to be exceeded more than once per year

iv. Arithmetic means

v. RSP means suspended particulates in air with a nominal aerodynamic diameter of 10μm and smaller

vi. Photochemical oxidants are determined by measurements of ozone only

4.2.3.3 The EIAO-TM stipulates that the hourly total suspended particulates (TSP) level should not exceed 500 mg/m³ (measured at 25°C and one atmosphere) for construction dust impact assessment. Standard mitigation measures for construction sites are specified in the Air Pollution Control (Construction Dust) Regulation. Notifiable and regulatory works are, also, under the control of the Air Pollution Control (Construction Dust) Regulation, to which the Environmental Protection Department should be informed.

4.2.4 Tunnel Air Quality Guidelines

4.2.4.1 Air pollutant concentration of various common vehicular gaseous emissions recommended in Tunnel Air Quality Guidelines specified under the EPD’s Practice Notes on Control of Air Pollution in Vehicle Tunnel 1995 should not be exceeded inside road tunnels or full noise enclosures. Table 4.2 presents the Tunnel Air Quality Guidelines values.

Table 4.2 Tunnel Air Quality Guidelines

Air Pollutant	Averaging Time (min)	Maximum Concentration
Air Pollutant	Averaging Time (min)	μg/m³	ppm
Carbon Monoxide (CO)	5	115,000	100
Nitrogen Dioxide (NO₂)	5	1,800	1
Sulphur Dioxide (SO₂)	5	1,000	0.4

4.3 Existing Environment

4.3.1 Introduction

4.3.1.1 Trunk Road T2 starts within the former Kai Tak Airport, which is currently an undeveloped area, and ends at Cha Kwo Ling. The former Kai Tak Airport will be redeveloped into various land uses including Commercial, Comprehensive Development Area, Residential, Government Institution or Community, Open Space and Other Specified Uses. At the Cha Kwo Ling and Kwun Tong end of the Trunk Road T2 alignment, the existing environment in the air quality assessment Study Area comprises a rural area with a mix of residential and institutional buildings and a mix of industrial uses, respectively. The Kowloon Bay portion of the study area is an urban commercial and industrial area.

4.3.2 Background Levels in Kwun Tong

4.3.2.1 The nearest Environmental Protection Department (EPD) Air Quality Monitoring Station (AQMS) is located in Kwun Tong and the latest five years of air quality statistics at this station, 2007 to 2011, are summarised in Table 4.3 to show the trend of the air quality in Kwun Tong.

Table 4.3 EPD Air Quality Monitoring Data at Kwun Tong Station (2007 – 2011)

Pollutant	Year	Highest 1-hour Average (mg/m³)	Highest Daily Average (mg/m³)	Annual Average (mg/m³)
Pollutant	Year	Kwun Tong	Kwun Tong	Kwun Tong
NO_x	2007	938	304	132
	2008	807	369	125
	2009	883	290	109
	2010	1008	417	116
	2011	798	277	116
	AQO	N/A	N/A	N/A
	Average of the Latest Five Years	887	331	120
NO₂	2007	316	160	63
	2008	243	139	59
	2009	249	134	58
	2010	242	123	59
	2011	285	155	63
	AQO	300	150	80
	Average of the Latest Five Years	267	142	60
SO₂	2007	375	114	19
	2008	258	69	17
	2009	168	57	11
	2010	99	34	10
	2011	115	42	12
	AQO	800	350	80
	Average of the Latest Five Years	203	63	14
O₃	2007	161	93	31
	2008	185	103	33
	2009	242	128	37
	2010	143	110	33
	2011	181	126	37
	AQO	240	N/A	N/A
	Average of the Latest Five Years	182	112	34
TSP	2007	N/A	198	82
	2008	N/A	160	72
	2009	N/A	186	70
	2010	N/A	142	67
	2011	N/A	126	74
	AQO	N/A	260	80
	Average of the Latest Five Years	N/A	162	73
RSP	2007	273	134	53
	2008	238	136	47
	2009	226	169	48
	2010	785*	681*	47
	2011	205	117	49
	AQO	N/A	180	55
	Average of the Latest Five Years	236	139	49

Note: Shaded cell denotes exceedance of relevant AQO.

The data of RSP marked with * were recorded when Hong Kong was affected by a dust plume originated from northern part of China in March 2010 and the average values do not include these data.

4.3.2.2 The air quality data in Table 4.3 shows that the 1-hour, 24-hour and annual averages for NO₂, 1-hour, 24-hour and annual averages for SO₂, 1-hour average for O₃, 1-hour, 24-hour and annual averages for TSP and daily and annual averages for RSP are all below the levels set by the AQOs.

4.4 Identification of Air Sensitive Receivers

4.4.1.1 Air Sensitive Receivers (ASRs) are identified in accordance with Annex 12 of the TM-EIAO, including domestic premises, hotels, hostels, temporary housing accommodation, hospitals, medical clinics, educational institutions, offices, factories, shops, shopping centres, places of public worship, libraries, courts of law or performing arts centre.

4.4.1.2 The planned developments projects in the Kai Tak Development (KTD) and the Cha Kwo Ling area have been discussed in Section 3. As per the respective Outline Zoning Plan (OZP) No. S/K22/4 gazetted on 14 September 2012 for the South Apron and OZP S/K15/19 gazetted on 17 June 2011 for the Cha Kwo Ling, Yau Tong and Lei Yue Mun, provided in Figures 9.5.1 to 9.5.6, there will be four hospitals planned to be implemented at the South Apron within 500m of the Trunk Road T2 project boundary, namely the Centre of Excellence in Paediatrics (CEP), the Centre of Excellence in Neuroscience (CEN), the New Acute Hospital (NAH), the future KTD private hospital. The construction schedules for the CEN, NAH and KTD private hospital, to be established at Site B of 3C1 at the South Apron, are not available at the time of preparation of this EIA Report (see summary list of concurrent projects in Appendix 3C), but the CEP is anticipated to be constructed between September 2013 and June 2017 and in operation in the middle of 2018 and, thus, has been identified as an future ASR during both the construction and operational phases, while the other hospitals would be identified as future ASRs during operational phase only. According to the Revised Technical Feasibility Study (TFS) for Establishment of Centre of Excellence in Paediatrics and Neuroscience and a New Acute Hospital in Kai Tak Airport, revised in July 2011, the preliminary layout plan shows an 8m set back from the site boundary.

4.4.1.3 A planning application (Application No. A/K22/13 (Appendix 2A)) for residential development at the site was approved by the Town Planning Board in March 2012. While a detailed construction schedule for the Kerry residential development is not available, it has been advised that the residential development will be in place towards the end of 2016 (see Concurrent Project summary table in Appendix 3C) and as such has been identified as an ASR for both the construction and operational phases. It is understood that the conditions of the land lease have specified a requirement to provide a 20m wide waterfront promenade along the harbour front side of the site. However, as the design of the development is not fixed and a waterfront promenade would also be an ASR, the potential setback has not been considered in this assessment.

4.4.1.4 At Cha Kwo Ling area, identified future ASRs include the future residential developments at YTB and the ex-CKLKMS. The layout of the YTB has been adopted from the latest Master Layout Plan in Planning Application No. A/K15/96 available on the Town Planning Board’s website (www.info.gov.hk/tpb). The layout of ex-CKLKMS is extracted from the current Planning Review of Development on the ex-CKLKMS. The proposed layouts of the developments have, also, been obtained from Planning Department in December 2012 and have been shown in Figure 4.2b.

4.4.1.5 Other existing ASRs have been identified with reference to the latest information provided on the survey maps, topographic maps, aerial photos, land status plans and confirmed by various site surveys undertaken.

4.4.1.6 The relevant stakeholders have also been approached to obtain the latest information on planning application, layout and building height, etc. The major planned uses in the vicinity of the area include the different land uses in the area including Commercial, Comprehensive Development Area, Residential, Government, Institution or Community, Open Space and Other Specified Uses of Kai Tak Future Development.

4.4.1.7 With reference to Section 3.4.5.3 of EIA Study Brief for the Project (ESB-203/2009), the study area for the air quality impact assessment has been defined as a distance of 500 metres from the boundary of the Trunk Road T2 project and from any work sites proposed under the project, and has been extended to include major existing and planned/committed air pollutant emission sources including tunnel portal/ventilation building(s) of the Central Kowloon Route (CKR) and the Tseung Kwan O-Lam Tin Tunnel (TKO-LTT), industrial uses in Kwun Tong and the Kowloon Bay Area.

4.4.1.8 Therefore, the air quality assessment has included ASRs within the site boundary, which may be potentially affected by the Project. The existing ASRs are industrial buildings, commercial buildings, parks at Kowloon Bay and Kwun Tong and the industrial buildings, residential buildings and sitting area at Cha Kwo Ling. The planned ASRs are the Commercial, Comprehensive Development Area, Residential, Government, Institution or Community, Open Space and Other Specified Uses of Kai Tak Future Development. The details of the identified representative ASRs are shown in Figures 4.1a, 4.1b, 4.2a and 4.2b and summarised in Table 4.4.

Table 4.4 Identified Representative Air Sensitive Receivers

ASR ID	Use		Landuse	No. of Storeys⁽³⁾		Assessment Heights (above ground level)⁽⁴⁾	Horizontal Distance to the Alignment (m)
Existing ASRs⁽¹⁾
KB1	Enterprise Square		Office	19		(1.5m)/ (1.5m, 5m, 10m, 15m, 20m)	260
KB2	Kai Fuk Industrial Centre		Industrial	9		(1.5m)/ (1.5m, 5m, 10m, 15m, 20m)	134
KB3	Enterprise Square Five		Office / Shopping Centre	34		(1.5m)/ (1.5m, 5m, 10m, 15m, 20m)	148
KB4	Enterprise Square Three		Office	41		(1.5m)/ (1.5m, 5m, 10m, 15m, 20m)	248
KB5	Kowloon Bay Waste Recycling Centre		Industrial	2		(1.5m)/ (1.5m, 5m, 10m, 15m, 20m)	195
CKL1	Sitting-out Area at Cha Kwo Ling Road		Recreational	-		(1.5m)/ (1.5m, 5m, 10m, 15m, 20m)	75
CKL2	Cha Kwo Ling Village		Residential	2		(1.5m)/ (1.5m, 5m, 10m, 15m, 20m)	306
CKL3	Cha Kwo Ling Village		Residential	2		(1.5m)/ (1.5m, 5m, 10m, 15m, 20m)	379
Planned ASR⁽²⁾
KTD1		Site 3C1 of Kai Tak Development	Hospital	22	(N/A)/ (1.5m, 5m, 10m, 15m, 20m)		18
KTD2		Site 3C1 of Kai Tak Development	Hospital	20	(N/A)/ (1.5m, 5m, 10m, 15m, 20m)		18
KTD3		Centre of Excellence in Paediatrics	Hospital	20	(1.5m)/ (1.5m, 5m, 10m, 15m, 20m)		8
KTD4		Centre of Excellence in Neuroscience and New Acute Hospital	Hospital	20	(N/A)/ (1.5m, 5m, 10m, 15m, 20m)		16
KTD5		Site 3E1 of Kai Tak Development	Commercial	33	(N/A)/ (1.5m, 5m, 10m, 15m, 20m)		1
KTD6		Kerry Godown Residential Development	Residential	34	(1.5m)/ (1.5m, 5m, 10m, 15m, 20m)		5
KTD7		Kowloon Bay Square	Recreational	--	(N/A)/ (1.5m, 5m, 10m, 15m, 20m)		41
KTD8		Site 4A1 of Kai Tak Development	Residential	22	(N/A)/ (1.5m, 5m, 10m, 15m, 20m)		359
KTD9		Site 4B2 of Kai Tak Development	Residential	22	(N/A)/ (1.5m, 5m, 10m, 15m, 20m)		350
CKL4		Ex CKL PCWA Advance Promenade	Recreational	--	(N/A)/ (1.5m, 5m, 10m, 15m, 20m)		35
CKL5⁽⁵⁾		Proposed Residential Development at ex-Cha Kwo Ling Kaolin Mine Site	Residential	18	(N/A)/ (1.5m, 5m, 10m, 15m, 20m)		248
CKL6⁽⁶⁾		Proposed Residential Development at Yau Tong Bay	Residential	14	(N/A)/ (1.5m, 5m, 10m, 15m, 20m)		483

Notes: (1): Existing ASRs are relevant to both the construction and operational phases of the Project.

(2): The majority of the planned ASRs are relevant to the operational phase only as they will be either being built concurrently or will not be present during the construction phase of the Trunk Road T2, except for ASR KTD3, the CEP Hospital, which is proposed to be complete and occupied in middle 2018 and the Kerry Godown Residential Development which is proposed to be complete at the end of 2016, both before completion of the Trunk Road T2 construction at the end of 2020.

(3): The number of floors have been calculated assuming the NSRs would be built to the maximum allowable elevation designated by the OZP (Figures 9.5.1 to 9.5.6) and assuming a height of 2.8m per floor.

(4): Heights of (1.5m)/(1.5m, 5m, etc) are for construction/operational phases respectively.

(5): As the future development of CKL5 will be on an elevated platform (+32 mPD or above) and the heights of the surrounding roads and ventilation buildings of Trunk Road T2 and TKO-LTT would be relatively lower than the level of the platform, it is concluded that assessment heights of up to 20m above ground level would be sufficient to determine the heights of the results with worst scenario.

(6) It is expected that the major emission source to affect the future development would be the open roads. Therefore, a maximum 20m assessment height is considered as appropriate.

4.5 Identification of Potential Air Quality Impacts and Representative Pollutants

4.5.1 Construction Phase

4.5.1.1 Potential construction air quality impacts would mainly be related to the dust nuisance from exposed site areas, including the reclamation areas when formed, movement of vehicles along unpaved roads, material handling and wind erosion of the site. The major sources of dust will be from the following construction activities for the Trunk Road T2 project:

· Site Preparation;

· Excavation;

· Road works;

· Foundation works;

· Construction of road and superstructures;

· Barging point and conveyor system;

· TBM launching and receiving shafts;

· Mucking out point for TBM process; and

· Wind erosion from open works site/areas and stockpiling areas.

4.5.1.2 According to Section 13.2.4.3 of USEPA AP-42, most of the particles generated during the construction activities have an aerodynamic diameter of <30 mm. Hence, it is appropriate to adopt Total Suspended Particulates (TSP), which have an aerodynamic diameter £ 30 mm as the representative pollutant during the construction phase.

4.5.1.3 According to the EIAO-TM and AQOs, 1-hour average, 24-hour and annual average concentrations of TSP should be considered. Therefore, the 1-hr average, 24-hour average and annual average concentrations of TSP have been assessed for the construction phase of the air quality assessment.

4.5.2 Operational Phase

4.5.2.1 Potential air quality impact during the operational phase of Trunk Road T2 and other major existing road networks would be dominated by vehicle gaseous emissions, either from open roads, or via the proposed tunnel portals and ventilation buildings. The vehicular emissions comprise a number of pollutants, including nitrogen oxides (NO_x), respirable suspended particulates (RSP), sulphur dioxides (SO₂), Carbon Monoxide (CO), toxic air pollutants (TAP) and lead (Pb) etc. Accordingly to “An Overview on Air Quality and Air Pollution Control in Hong Kong” published by EPD¹, the emissions from motor vehicles are the main sources of NO₂ and RSP at street level in Hong Kong and therefore, they are considered to be the key air pollutants for road projects. For the other pollutants, due to the low concentration in the vehicular emissions, they are not considered as the key pollutants for the purposes of this air quality assessment of the EIA report, as discussed in the following sections.

Nitrogen Dioxide

4.5.2.2 Nitrogen oxides (NO_x) are a major pollutant emitted by vehicles during the combustion of fossil fuel. According to the EPD 2010 Hong Kong Emission Inventory Report², the second largest contributor of NO_x is road transport, which contributed 30% of the total in 2010. In the presence of Ozone (O₃₎ and Volatile Organic Components (VOC) in the atmosphere under sunlight, NO_x would be converted to Nitrogen Dioxide NO₂. The operation of the Trunk Road T2 would potentially increase the traffic flow and, hence, the emissions of NO_x. Therefore, NO₂ is one of the key pollutants for the air quality assessment of the EIA report. In accordance with the AQOs, 1-hour, 24-hour and annual averaged NO₂ concentrations would be assessed to determine the compliance of AQOs.

Respirable Suspended Particulates

4.5.2.3 Respirable Suspended Particulates (RSP) are particulates with a nominal aerodynamic diameter of 10mm or less. According to the 2010 Hong Kong Emission Inventory Report published by EPD, road transport is the second largest contributor of RSP at 21% of the total in 2010. Increasing the traffic flow with the operation of Trunk Road T2 would potentially increase the RSP concentration. Therefore, RSP is, also, considered to be a key pollutant for the air quality assessment of the EIA report. In accordance with the AQOs, 24-hour and annual averaged RSP concentrations would be assessed to determine the compliance of AQOs.

Sulphur Dioxide

4.5.2.4 Sulphur dioxide (SO₂) is generated primarily due to the sulphur content of fossil fuels. According to the 2010 Hong Kong Emission Inventory Report published by EPD, the dominant sources of SO₂ in Hong Kong are mainly generated from electricity generation and navigation, which contributed 50% and 48% of the total emission in total in 2010. While motor vehicles can, also, generate SO₂ during combustion diesel fuel. However, according to “Cleaning the Air at Street Level” from EPD’s website³, ultra low sulphur diesel (ULSD) with a sulphur content of only 0.005% is the statutory minimum requirement for motor vehicle diesel. With the use of ULSD, the 2010 Hong Kong Emission Inventory Report indicates that road transport contributed less than 1% of SO₂ in total. In addition, as from 1 July 2010, EPD has tightened the statutory motor vehicle diesel and unleaded petrol specifications to Euro V level, which tightened the cap on sulphur content from 0.005% to 0.001%.

4.5.2.5 In addition, as shown in Table 4.1, the measured 1-hour, 24-hour and annual average SO₂ concentration at EPD’s AQMS at Kwun Tong are well below the AQOs. Therefore, with the above reasons, it is concluded that the SO₂ would not be a critical air pollutant and has not been assessed in this EIA Report.

Carbon Monoxide (CO)

4.5.2.6 Carbon monoxide is the pollutant emitted from the incomplete combustion of the fossil fuel of the vehicles. According to the 2010 Hong Kong Emission Inventory Report published by EPD, road transport is the dominant contributor in the emission of CO which contributed 68% of total in 2010. However, by referring to the “Air Quality in Hong Kong 2011” published by EPD, the measured 1-hour average (ranging from 1490 mg/m³ to 4030 mg/m³) and 8-hour average (ranging from 1459 mg/m³ to 2610 mg/m³) recorded at EPD’s monitoring stations are well below the AQOs. Therefore, it is concluded that the CO would not be a critical air pollutant and has not been assessed in this EIA Report.

Ozone

4.5.2.7 Formation of Ozone (O₃) results from a set of complex chain reactions between various chemical species including NO_x and VOC, under favourable meteorological conditions. Therefore, the formation of O₃ is affected by the concentrations of NO_x and VOC, atmospheric oxidation, temperature, radiation, etc in the atmosphere. Overall higher O₃ levels would not occur at the urban area or industrial areas because of the presence of high levels of NO_x such that the O₃ reacts with NO to give NO₂ and, thus, results in O₃ removal. Therefore, O₃ is not considered as a key air pollutant during the operation of the Trunk Road T2.

Lead (Pb)

4.5.2.8 Leaded petrol has been banned in Hong Kong since April 1999. According to the EPD “Air Quality in Hong Kong 2011”⁴, the measured ambient lead concentrations ranged from 20ng/m³ to 104ng/m³ and were well below the AQOs. Therefore, lead is not considered as a key pollutant for the air quality assessment in the EIA report.

Toxic Air Pollutants (TAPs)

4.5.2.9 There are six kinds of Toxic Air Pollutants (TAPs) monitored in Hong Kong including polychlorinated biphenyls (PCBs), dioxins, polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), carbonyls, and toxic elemental species.

4.5.2.10 As stated in “Assessment of Toxic Air Pollutant Measurements in Hong Kong, Final Report”⁵, dioxins, carbonyls, PCBs and most toxic elemental species are not considered as primary sources of vehicular emissions. Therefore, these pollutants are not considered as key pollutants for the air quality assessment in the EIA report.

4.5.2.11 Diesel Particulate Matters (DPM) is part of the overall RSP and vehicular emissions are one of the major sources of DPM. However, the Government has embarked on the following three key programmes to reduce the diesel particulates level at the roadside⁶: (a) the LPG taxi and light bus programme; (b) the introduction of an advanced test to check diesel vehicle smoke emission; and (c) the retrofitting of pre-Euro diesel commercial vehicles with diesel oxidation Catalysts (DOCs). According to EPD’s website⁶, franchised bus companies have, also, retrofitted their Euro I buses with diesel oxidation catalysts (DOCs) and Euro II and III buses with diesel particulate filters (DPFs). A DPF can reduce particulate emissions from diesel vehicles by over 80%.

4.5.2.12 As recommended by “Assessment of Toxic Air Pollutant Measurements in Hong Kong, Final Report”, elemental carbon (EC) is used as a surrogate for DPM, and with reference to “Measurements and Validation for the 2008/2009 Particulate Matter Study in Hong Kong”, EC showed a significant decrease in concentration from 2001 to 2009 in Hong Kong, i.e. -47.5%, -30.0% and -28.3% at Mong Kok, Tsuen Wan and Hok Tsui Monitoring Sites respectively. Based on the continual efforts noted above to reduce the particulate emission from the vehicles, therefore, DPM is not considered as a key pollutant for the air quality assessment in the EIA report.

4.5.2.13 Polycyclic Aromatic Hydrocarbons (PAHs) are organic compounds of two or more fused benzene rings, in liner, angular or cluster conformations. Local vehicular traffic is an important source of PAHs. With reference to “Assessment of Toxic Air Pollutant Measurements in Hong Kong, Final Report”, the most important TAP is Benzo[a]pyrene, and it is often selected as a marker for the PAHs. The EU Air Quality Standards for PAHs (expressed as concentration of Benzo[a]pyrene) is 1 ng/m³ for annual average. With reference to “Air Quality in Hong Kong 2011”, annual average concentrations of PAHs (Benzo[a]pyrene) measured at EPD’s monitoring stations (Tsuen Wan and Central/Western) were 0.22ng/m³, which is well below the EU Standards. Therefore, PAHs are not considered as key pollutants for the air quality assessment in the EIA report.

4.5.2.14 Volatile Organic Compounds (VOCs) are of great concern due to the important role in the health and environmental problems. The US EPA has designated many VOC, including those typically found in vehicular emission, as air toxic. According to “Assessment of Toxic Air Pollutant Measurements in Hong Kong, Final Report”, among the VOC compounds, benzene and 1,3-butadiene are the most significant VOCs for Hong Kong. The UK Air Quality Standards for benzene and 1,3-butadiene are 5.0 mg/m³ and 2.25 mg/m³ respectively. According to the “Air Quality in Hong Kong 2011”, annual average concentrations of benzene and 1,3-butadiene at EPD’s monitoring stations (Tsuen Wan and Central/Western) were 1.53 – 1.62 mg/m³ and 0.13 mg/m³, respectively, which is well below the UK Standards. Therefore, VOCs are not considered as key pollutants for the air quality assessment in the EIA report.

Odour

4.5.2.15 Odour is mainly generated from high Acid Volatile Sulfides (AVS) contained in sediments under highly negative redox conditions which then result in the release of hydrogen sulphide (H₂S) gas. With reference to the KTD EIA report, the major odour emission sources of concern are for the Trunk Road T2 project are the marine sediments of the Kai Tak Nullah, Kai Tak Approach Channel and the Kwun Tong Typhoon Shelter. However, as mentioned in Section 3.3.1.1, the tunnel would be constructed by using the TBM method in order to avoid disturbance to the seabed and negate the need for marine sediments to be dredged and removed. Therefore, odour is not considered to be a significant potential issue during the construction phase of the Trunk Road T2.

4.5.2.16 Appendix 3D shows the road network which will be included in the air quality assessment for Kai Tak/Kowloon Bay and Kwun Tong/Cha Kwo Ling areas and Figure 3.4 shows the locations of the tunnel portals and ventilation buildings. In order to assess the cumulative air quality impact, pollutant-emitting activities within the study area would be reviewed in the air quality impact assessment, including:

· Vehicle gaseous emissions from the open sections of Trunk Road T2 and the adjacent existing and planned trunk and local road networks; and

· Emissions from ventilation buildings and tunnel portals of Trunk Road T2 and concurrent projects.

4.6 Concurrent Projects

4.6.1 Background

4.6.1.1 The tentative construction period (as detailed in Section 3) and first operational year of the Trunk Road T2 would be December 2015 to December 2020, and 2021 respectively. A summary of potential projects that will be concurrent to the Trunk Road T2 during the construction and/or operational phases are provided in Appendix 3C. Within 500m of the project boundary of the Trunk Road T2, cumulative impacts may arise from the concurrent projects discussed below.

4.6.2 Kai Tak Development

4.6.2.1 Construction works for the Kai Tak Development (KTD), and the regional delivery Roads D3, D3a, D4 and D4a, are scheduled to be completed by December 2016. Hence, cumulative construction dust impacts could occur between December 2015, when the Trunk Road T2 commences construction, and December 2016. Hence, a cumulative construction dust impact assessment for KTD has been undertaken.

4.6.2.2 During the operational phase of the Trunk Road T2 project, cumulative traffic air quality impacts are anticipated. The respective concurrent road alignments and respective mitigation measures have been obtained from the Schedule 3 EIA report which is reference EIA-157/2009 (Agreement No. CE 35/2006 (CE) Kai Tak Development Engineering Study cum Design and Construction of Advance Works – Investigation, Design and Construction Environmental Impact Assessment Report, approved on 4 March 2009). Cumulative traffic air quality impacts from the KTD, have, therefore, been assessed.

4.6.3 Central Kowloon Route

4.6.3.1 Construction works for the Central Kowloon Route (CKR) are anticipated to be carried out between January 2015 and December 2020. Hence, cumulative construction dust impact assessment from the CKR would be anticipated. Relevant information for the dust impact assessment has been obtained from the Final CKR EIA Report (Agreement No. CE 43/2001 (HY) Central Kowloon Route – Design and Construction Final Environmental Impact Assessment Report 207722-REP-042-03, dated January 2013).

4.6.3.2 During the operational phase of the Project, cumulative traffic air quality impacts of CKR are anticipated. Therefore, respective road alignments of CKR within the 500m study area of the Trunk Road T2, and respective mitigation measures, have been obtained from the Final CKR EIA Report. Cumulative traffic air quality impact from CKR has, therefore, been assessed.

4.6.3.3 It should be noted that the aforementioned Final CKR EIA Report has not been approved under the EIAO but represents the best available information at the time of reporting of this Trunk Road T2 EIA report.

4.6.4 Tseung Kwan O – Lam Tin Tunnel

4.6.4.1 Construction works for the TKO-LTT are anticipated to be carried out between January 2016 and December 2020. Hence, potential cumulative construction dust impacts are anticipated for the whole construction period of Trunk Road T2 from December 2015 to December 2020. As such, cumulative dust impacts have been assessed and the relevant information for the assessment has been obtained from the Final EIA Report (Tseung Kwan O – Lam Tin Tunnel and Associated Works – Investigation, dated January 2013).

4.6.4.2 During the operational phase of the Project, cumulative traffic air quality impacts of TKO-LTT are anticipated. Therefore, respective road alignments of CKR within 500m study area of the Trunk Road T2, and respective mitigation measures have been obtained from the Final TKO-LTT EIA Report.

4.6.4.3 It should be noted that the aforementioned draft TKO-LTT EIA Report has not been approved under the EIAO but represents the best available information at the time of reporting for this Trunk Road T2 EIA report.

4.6.5 Eastern Harbour Tunnel

4.6.5.1 The portal and the ventilation buildings of Eastern Harbour Tunnel on the Kowloon side are within the 500m study area of the Trunk Road T2. Therefore, the emissions from this source have been included in the operational air quality assessment. For consistency, the emissions data has made reference to the EIA report of TKO-LTT.

4.6.6 Shatin to Central Link – Tai Wai to Hung Hom Section (SCL (TAW-HUH))

4.6.6.1 The Shatin to Central Link – Tai Wai to Hung Hom Section (SCL (TAW-HUH)) is an extension of the Ma On Shan Line from Tai Wai to Hom Man Tin Station and connects to the West Rail Line at Hung Hom Station. The major civil construction works of SCL (TAW-HUH) commenced in 2012 and will be completed in 2016. Therefore, the construction works related to the Kai Tak Station will be a potential cumulative dust sources with Trunk Road T2 during December 2015 to December 2016. All the construction works of SCL (TAW-HUH) which have the potential to generate dust and are within the 500m from the Trunk Road T2 boundary during this period have been assessed. The information provided in the SCL – NEX/2206 EIA Study for Tai Wai to Hung Hom Section Final Environmental Impact Assessment Report (reference: EIA-200/2011) is the most up to date, the assumptions for the construction dust impact assessment have been adopted from this source.

4.6.7 Centre of Excellence in Paediatrics

4.6.7.1 Construction works for the Centre of Excellence in Paediatrics (CEP) hospital is anticipated to be carried out between September 2013 and June 2017. Hence, cumulative construction dust impact is anticipated from December 2015 to June 2017. However, as it is anticipated that the dust generated from the construction works of CEP would not be significant with appropriate mitigation measures. Therefore, no cumulative construction dust impact from CEP is anticipated. The CEP is, however, identified as a future ASR during both construction and operational phases as it is anticipated to be operational in the middle of 2018.

4.6.7.2 During the operational phase, the chimney emission from the CEP would contribute to the cumulative air quality impact. However, as there is no updated information available, the information of the chimney emission has been obtained from the KTD Schedule 3 EIA Report.

4.6.8 Other Lands Proposed for Hospital Use

4.6.8.1 There are in total four hospitals proposed to be established at the South Apron (including CEP). Except for the CEP, which has a scheduled plan for establishment, as mentioned in Section 4.6.6, the CEN, NAH and the future KTD private hospital are still in the planning stage and no construction or operational schedules are available. Notwithstanding, it is assumed that the developments will be operational during the operational phase of the Trunk Road T2, that is after 2021. However, no cumulative construction dust impact assessment for the CEN, NAH and the future private KTD hospital would be assessed as there it is anticipated that no significant dust impact would be generated from the construction works of the hospitals with appropriate mitigation measures.

4.6.9 Roads L10 and L18

4.6.9.1 Construction works for the Roads L10 and L18 are anticipated to be carried out between August 2019 and May 2020. According to the construction programme of Trunk Road T2, the dusty construction works at South Apron would be completed by this time, with only commissioning tests being carried out. Therefore, cumulative construction dust impacts have not been carried out for Roads L10 and L18. For the operational phase, the cumulative traffic air quality impact of the roads has been assessed.

4.6.10 Extension of Existing Footbridge FB-02

4.6.10.1 The extension of existing footbridge FB-02 will be constructed concurrently with the Trunk Road T2. However, given the minor nature of the works, it is anticipated that the construction dust impact would not be significant, and, therefore, cumulative dust impacts from this project have not been assessed. There would be no operational phase cumulative impacts.

4.6.11 Site Formation for Kai Tak Cruise Terminal Development (Stages 1 & 2)

4.6.11.1 Construction works for the site formation for Kai Tak Cruise Terminal Development (Stage 1 & Stage 2) will be completed before the commencement of the construction works of the Trunk Road T2. Hence, cumulative construction dust impact assessment is not required. However, during the operational phase of Trunk Road T2, the operational emissions from the cruise ships at the cruise terminal would be cumulative sources and therefore, the emissions from the cruise liners have been included in the operational air quality impact assessment.

4.6.12 Kwun Tong Typhoon Shelter

4.6.12.1 Emissions from the marine vessels operating in the Kwun Tong Typhoon Shelter have the potential for cumulative air quality impact during the operational phase of the Trunk Road T2. The details of the emissions from the KTTS have made reference to the Trunk Road T2 marine traffic survey undertaken in 2009, as detailed in Section 4.8.8 below, and the Schedule 3 EIA report of the Kai Tak Development.

4.6.13 Projects Completed or Ceased Operation before Commencement of Trunk Road T2

4.6.13.1 According to the construction schedules for the following projects, they are all scheduled to be completed before the commencement of the construction works of the Trunk Road T2 and, therefore, have been excluded from the cumulative construction air quality impact assessment:

· Kai Tak Development – Advance Infrastructure Works for Developments at the Southern Part of the Former Runway (Stage 1);

· District Cooling System at the Kai Tak Development – Phase 1;

· District Cooling System at the Kai Tak Development – Phase 2;

· Installation of Submarine Gas Pipelines and Associated Facilities from To Kwa Wan to North Point for Former Kai Tak Airport Development;

· Provision of Interception Facilities at Jordan Valley Box Culvert;

· Kwun Tong Public Works Cargo Area; and

· Kerry Dangerous Goods Godown.

4.6.14 Projects Outside 500m Study Area of Trunk Road T2

4.6.14.1 The following projects would not be within 500m study area of Trunk Road T2 and, therefore, have been excluded from the cumulative air quality impact assessment:

· Ventilation buildings of CKR;

· Construction of Road D3 & D4 – Section of Road D3 in South-eastern direction to taxiway bridge;

· Road D1 and Associated Infrastructure Works;

· Road L9 & L16 Entrustment works to SCL;

· Kai Tak Development – Reconstruction and Upgrading of Kai Tak Nullah project;

· Construction of Road D2 & associated Works;

· To Kwa Wan Typhoon Shelter;

· Kai Tak Tunnel;

· Multi-purposed Stadium Complex;

· Shatin to Central Link (Cross Harbour Section);

· Wai Chai Development Phase II (WDII); and

· Junction Improvement Works at Kowloon Bay.

4.6.15 Projects Lacking Detailed Information or No Significant Air Quality Impact Anticipated

4.6.15.1 Due to a lack of project details including design, programme and engineering information or no significant dust impact is anticipated with appropriate mitigation measures for the construction of the projects, the following projects have not been included in the cumulative impact assessment for both construction and operational phases:

· District Cooling System at the Kai Tak Development – Phase 3;

· The Centre of Excellence in Neuroscience and the New Acute Hospital;

· Future KTD Hospital (located at Site 3C-1);

· Kai Tak Development – Waterfront Promenade fronting the CEP;

· Extension of Existing Footbridge FB-02;

· Proposed Footbridge FB-03;

· Proposed Footbridge FB-04;

· Proposed Footbridge FB-06;

· Container Terminal 10 Development (CT10);

· Kwai Tsing Basin Dredging;

· Proposed Ex CKL PCWA Advace Promenade; and

· Planned Residential Development in CKL/YT and TKO.

4.6.15.2 Table 4.5 provides a summary of all identified concurrent projects within the 500m study area included in the cumulative impact assessment for the Trunk Road T2.

Table 4.5 Identified Concurrent Projects and Aspects of Cumulative Impacts

Name of Concurrent Projects	Air Quality Assessment
Name of Concurrent Projects	Future ASRs	Construction Phase⁽¹⁾	Operational Phase⁽¹⁾
Central Kowloon Route	--	ü	ü
Extension of Existing Footbridge FB-02	--	--	--
Kai Tak Development	ü	ü	ü
Kai Tak Cruise Terminal Development (Stage 1 & 2)	--	--	ü
Kwun Tong Typhoon Shelters	--	--	ü
Kwun Tong Public Cargo Works Area	--	--	--
Kerry Dangerous Goods Godown	--	--	--
Road D3 & D3A	--	ü	ü
Road D4 & D4A	--	ü	ü
Road L18	--	--	ü
Road L10	--	--	ü
Shatin to Central Link (SCL)	--	ü	--
Tseung Kwan O – Lam Tin Tunnel	--	ü	ü
Eastern Harbour Tunnel	--	--	ü
Centre of Excellence in Paediatrics	ü	--	ü
Kerry Godown Residential Development	ü	--	--

Note (1): identifies projects with notable air emission sources to be cumulatively assessed.

4.6.15.3 The method of assessment to be applied to the concurrent projects which could potentially contribute to cumulative air quality impacts during the Trunk Road T2 construction and operational phases are detailed in Table 4.6 below.

Table 4.6 Method of Assessment of Potential Concurrent Emission Sources

Project	Model Applied for Assessment
Construction Phase
TKO-LTT	FDM
CKR	FDM
SCL (Kai Tak Station)	FDM
Roads D3a and D4a	FDM
Kai Tak Development	FDM
Operational Phase
Open Roads of TKO-LTT	CALINE4
Roads with Enclosure, Tunnel Portals and Vent Shafts of TKO-LTT	ISCST3
Open Roads of CKR	CALINE4
Tunnel Portals of CKR	ISCST3
Tunnel Portals and Vent Shafts of Eastern Harbour Crossing	ISCST3
Open Roads of Kai Tak Development	CALINE4
Cruise Terminal of Kai Tak Development	ISCST3
Kwun Tong Typhoon Shelter	ISCST3
Chimney of Hospital at Kai Tak Development	ISCST3
Existing Open Roads within the 500m Study Area	CALINE4

4.7 Construction Phase Assessment Methodology

4.7.1 General Approach

4.7.1.1 The assessment approach will be based on the requirements as specified in the EIA Study Brief (ESB-203/2009). The criteria and guidelines for assessing air quality impacts as stated in Annexes 4 and 12 of the EIAO-TM would be followed. The requirements as stipulated under the Air Pollution Control (Construction Dust) Regulation would be followed to ensure that construction dust impacts would be controlled within the relevant standards as stipulated in the EIAO-TM.

4.7.1.2 The quantitative assessment of construction dust impacts has been conducted using the Fugitive Dust Model (FDM) as approved by EPD, which is a Gaussian Plume model designed for computing air dispersion model for fugitive dust sources. Modelling parameters including the dust emission factors, particle size distribution, surface roughness, etc are specified in the EPD’s Guideline on choice of models and model parameters and the Compilation of Air Pollutant Emission Factors, USEPA AP-42, 5th Edition, January 1995, USEPA AP-42.

4.7.1.3 It is assumed that dust emission would be generated during the daytime working hours between 7:00am and 7:00pm, except for the stockpiling area of WA3. WA3 would also be in operation during the nighttime because the TBM would operate 20 hours per working day with a 4 hour break, but there is no regular operating pattern for the TBM. As a worse-case scenario for the impact assessment, the TBM would assumed to be operated 24-hour per day and therefore, the stockpiling area at WA3 would be operated 24 hours per working day. Any construction works outside this period and during weekends/holidays would be reviewed for construction dust impact assessment as necessary.

4.7.2 Identification of Pollution Sources and Emission Inventory

4.7.2.1 Potential construction air quality impacts would mainly be related to dust nuisance from exposed site areas, including the excavation areas, movement of vehicles along unpaved roads, backfilling, wind erosion, transportation/handling of C&D materials, including transfer to the barging point via conveyor and loading and unloading of excavated materials at the barging point. The locations of work sites and works areas for the assessment are shown in Figure 3.8. It would be anticipated that the excavation and backfilling activities would involve significant quantity of earthworks and silty material handling and, hence, there is the potential for dust impacts at adjacent ASRs.

4.7.2.2 Other air quality parameters are not considered key to the construction stage due to the relatively small number of plant that will be utilised on site. In addition, the dust generated during the construction works will not contain a significant proportion of fine particulates (less than 10 µm) which are deemed to the respirable and therefore, the 1-hr average and 24-hr average TSP concentrations, in addition to the annual average TSP concentrations have been evaluated to assess the short and long term dust impact from the Project on the ASRs, respectively and respirable suspended particulates (RSP) have not been assessed.

4.7.2.3 The assessment of construction dust impacts has been carried out based on the following assumptions of the general construction activities:

· All construction activities at all work sites, work areas would be undertaken concurrently in order to assess the worst case situation;

· Heavy construction activities will include site clearance, ground excavation, cut and fill operations, construction of the associated facilities, material handling at stockpiling area and construction traffic and hauling over the sites;

· Haul roads within the work sites would be paved and water spraying would be provided to keep them wet and assumed with 100% active area;

· A wind erosion area of 30% has been assumed to occur at any time for the hourly and daily TSP prediction and 6% at any time for the annual TSP. However, to be conservative, a 100% active area screening test (Tier 1) has been undertaken initially for the short term hourly and daily TSP assessment as detailed in the modelling approach section below;

· Active operating areas of 30% have been assumed at any time for the short term hourly and daily TSP predictions and 6% active operating area at any time for long term annual TSP predictions of mitigated scenario for all sites other than the fixed haul road surface has been assumed. The justification of the percentage of active works areas is presented in Appendix 4A. However, to be conservative a 100% active area screening test has been undertaken initially for the short term hourly and daily TSP assessment (i.e. Tier 1) as detailed in the modelling approach section below;

· Conveyor belts are assumed to be fully covered during use and, hence, fugitive dust emissions would not be anticipated;

· Dust emissions during loading / unloading by conveyor belt and dump trucks at the barging point have been assessed; and

· Construction periods are assumed to be 30 days per month, 6 working days per week and 12 operation hours per day from 0700 to 1900, except for the stockpiling area at WA3 which would be operated 24 hours per day as a result of the TBM operating during the nighttime as well. An addition of 17 public holidays per year with no construction works has also been assumed for the assessment.

4.7.2.4 The emission factors for fugitive dust have been determined with reference to the Compilation of Air Pollutant Emission Factors, USEPA AP-42, 5th Edition, January 1995. The Fugitive Dust Model (FDM) has been used for the simulation of the construction dust dispersion from the areas of emissions. The key assumptions for the calculation of dust emission factors are summarised in Table 4.7 below.

Table 4.7 Assumptions for Calculation of Dust Emission Factors

Activities	Reference ^[1]	Operating Sites	Equations and Assumptions ^[1]
Heavy construction activities including land clearing, ground excavation, cut and fill operations, construction of facilities, material handling at stockpiles, equipment traffic and hauling over the site areas.	S.13.2.3.3	All construction and excavation sites	E = 1.2 tons/acre/month of activity or 2.69Mg/hectare/month of activity
Wind erosion.	S.11.9, Table 11.9.4	All construction sites, stockpile areas, barging area (all open sites)	E = 0.85 Mg/hectare/yr (24 hour emission)
Loading and unloading at barging point.	S.13.2.4	Barging point	k is particle size multiplier U is average wind speed M is material moisture content

Note: [1] USEPA Compilation of Air Pollution Emission Factors (AP-42)

4.7.2.5 The dust emissions from construction vehicles and the loaded/unloaded vehicles movements would be limited to within the confines of the works sites, works areas, stockpiling areas, respectively and the equation for Heavy Construction (as in AP-42 S.13.2.3.3) would take this factor into account. The major dust generating activities at the barging point would be assumed to mainly originate from the loading/unloading of C&D materials. The barging point would be assumed to be equipped with the following measures:

· Road surfaces within barging point areas would be paved;

· Dust enclosures with watering would be provided along the loading ramps and enclosed conveyor belts for unloading the C&D materials to the barge for dust suppression;

· Vehicles would be required to pass through designated wheel washing facilities before leaving the barging point; and

· Regular watering would be imposed on all exposed surfaces and activities.

4.7.2.6 In addition, 3-sided barriers are proposed to be provided around stockpiling areas at WA3 and WA4.

4.7.3 Modelling Approach

4.7.3.1 The density of dust has been assumed to be 2.5g/m³. According to S.13.2.4.3 of USEPA AP-42, the particle size distribution is assumed as 1.25mm, 3.75 mm, 7.5 mm, 12.5 mm and 22.5 mm with 7%, 20%, 20%, 18% and 35% size distribution, respectively. As the study area is categorised as “urban”, the average monitoring data in the latest 5 years (i.e. 2007 to 2011) from the EPD’s air quality monitoring station in Kwun Tong which is shown in Table 4.8 has been adopted as the background concentration. Based on this, the average TSP concentration has been calculated as 73µg/m³. A surface roughness of 100cm would be assumed in the model to represent the terrain where applicable.

Table 4.8 Annual Average TSP Results from EPD Kwun Tong Air Quality Monitoring Station (2007 to 20011)

Pollutant	Annual Average
Pollutant	2007	2008	2009	2010	2011
TSP (AQO: 80mgm^-3)	82	72	70	67	74

Note: Underlined figure represents an exceedance of the AQO

4.7.3.2 The latest available sequential meteorological data with at least 90% valid data recorded at King’s Park, Hong Kong Observatory and Kai Tak Weather Station obtained from Hong Kong Observatory (HKO), 2011, has been used to predict the 1-hour, 24-hour average and annual average TSP concentrations at representative ASRs. The following meteorological conditions have been adopted for the calculation of 1-hour, 24-hour and annual average TSP concentrations:

· Wind speed: hourly record from Kai Tak Weather Station meteorological data;

· Wind direction: hourly record from Kai Tak Weather Station meteorological data;

· Stability class: hourly record from meteorological data at the Kai Tak Weather Station. It should be noted that the stability class G obtained from the HKO has been combined with class F for the purposes of the modelling and stability classes A-F applied;

· Mixing height: daily record from meteorological data at King’s Park Weather Station in Year 2011; and

· Temperature: hourly record from meteorological data at HKO Weather Station.

4.7.3.3 Hourly, 24-hour and annual average TSP concentrations at the representative ASRs near to the construction work areas have been predicted with the use of the sequential meteorological data. For the hourly meteorological data which is not available, the results of the related hours would not be considered.

4.7.3.4 Fugitive dust modelling would be conducted at a height of 1.5m above local ground level of the ASRs as all of the works of Trunk Road T2 are at grade. The maximum cumulative 1-hour, 24-hour and annual averaged TSP concentrations at the selected ASRs have been determined and pollutant contours have been presented at the worst hit level. A 50 x 50m grid contour would be used to investigate the pollutant distribution for the assessment period.

4.7.3.5 The air quality impact assessment has been carried out in accordance with the construction programme shown in Appendix 3A. All the works sites and Works Areas would be expected to have continuous works activities throughout the entire construction period. There will be a barging point at the South Apron, comprising one loading and unloading location, and it is proposed that the waste disposal trucks from the Trunk Road T2 project would be directed to this barging point, as well as material transferred from WA3 via conveyor (Figure 3.6).

4.7.3.6 According the construction programme detailed in Section 3, the Trunk Road T2 project will be constructed on several concurrent work fronts. Therefore, in order to assess the worst case scenario, all the construction activities have been modelled at the same time to represent the worst case situation.

4.7.3.7 In respect of the short-term assessment of the 1-hour and 24-hour average TSP concentrations, it has been assumed that all the construction work activities and equipment would not be concentrated in certain areas of the site closest to the ASRs at any time during the construction period. However, a “Tier 1” assessment has been carried out as a worst case scenario in which it has been assumed that all the active works site areas would be 100% active.

4.7.3.8 After carrying out the Tier 1, the areas where construction dust impacts have been noted to exceed the AQO at specific ASRs could be subject to a “Tier 2” assessment. The Tier 2 assessment would identify the works areas closest to the ASR being affected and instead of assuming a 100% active area for this location, the actual construction programme would be reviewed and 30% of active area determined based upon the scheduled works only. The justification of the percentage of active area is presented in Appendix 4A.

4.7.3.9 For the long-term assessment of the annual average TSP concentrations, it should be noted that the sequencing of works for each works activity over each works site or area would be determined by the Contractor and is not known at this stage. However, due to the constrained size of the works sites and areas and the construction programme constraints, it would be necessary for active construction activities to be undertaken at moving multiple work faces spread across each site. Therefore, it is not feasible to identify the exact locations of individual dust emission sources. As such, for the long term annual predictions of mitigated scenario, the dust modelling assessment has assumed that the dust emissions would be distributed across the whole area of each site to reasonably represent this mode of working and the dust emission rates have been proportioned to produce the effect of 6% active works site. The justification for the percentage of active works areas for the long terms assessment is presented in Appendix 4A.

4.7.3.10 However, for the haul roads at the works sites, because of their locations them are well defined, the 100% active area is still applied for the Tier 2 short term assessment and long term assessments, which represents a very conservative assumption because it assumes a continuous use of the haul road by traffic during the full construction period.

4.7.3.11 The maximum capacity of the barging point (Conveyor belt + dump trucks) would be 850 m³/hour (i.e. 1573 Mg/hour) and is assumed for each operating hours of the construction period of Trunk Road T2 which represents the worst case scenario.

4.7.3.12 The locations and dimensions of the emission sources for the Tier 1 and Tier 2 short and long term assessments of the Trunk Road T2 site are shown in Appendix 4B, including detailed calculations of emission rates.

4.7.3.13 All cumulative impacts of the relevant concurrent projects with Trunk Road T2, as detailed in Section 4.6 above, have been evaluated and assessed. For the concurrent projects, emission sources and factors have been extracted from the respective EIA Reports for both wind erosion and general construction activities. The locations and dimensions of the emission sources of the concurrent projects are shown in Appendix 4C, in which detailed calculations of emission rates are, also, presented. For the concurrent projects, reference will be made to relevant EIA reports for assessing the cumulative dust impact.

4.7.4 Level of Uncertainty

4.7.4.1 The FDM model used for the modelling of the construction dust impact assessment is the accepted models for calculating the dust impact for the construction activities and which have made reference to the Guidelines on Choice of Models and Mode Parameters.

4.7.4.2 According to the construction programme, the construction works of each section of the drainage would not be carried out at the same time. However, for the purposes of the dust assessment, all the construction works areas have been assumed to be 100% active to present a worst case scenario in this assessment. Utilising this assumption has made the approach of the assessment more conservative.

4.7.4.3 Uncertainties in the assessment of impacts have been considered when drawing conclusions from the assessment and worst case scenarios have been adopted.

4.8 Operational Phase Assessment Methodology

4.8.1 General Approach

4.8.1.1 The overall methodology for the air quality impact assessment within the 500m Study Area from Kowloon Bay to Cha Kwo Ling is as follows:

· On the assumption that the worst case assessment year will be determined by the results of EMFAC-HK v2.1;

· Use of the last 5 years data from EPD’s Air Quality Monitoring Station (AQMS) at Kwun Tong to quantify the background air quality. Although it is expected that the assessment year will be Year 2021 (to be determined by EMFAC-HK), it is expected that the background air quality will be improved in the future, thus, adopting the results from the last 5 years from EPD’s AQMS for Kwun Tong would be expected to be more conservative; and

· Use of near field dispersion models i.e. CALINE4 for line sources and ISCST3 for discrete point and volume sources to quantify the air quality impacts at local scale from sources including open road emissions and emissions from chimneys of industrial premises (Kowloon Bay and Kwun Tong), ventilation buildings and tunnel portals of Trunk Road T2, CKR, TKO-LTT and Eastern Harbour Crossing (at Kowloon side), Kwun Tong typhoon shelter and the Kai Tak Development.

4.8.1.2 The overall methodology is illustrated below:

* Assessment year = maximum EMFAC-HK emission year from modelled years 2021, 2026 and 2036

4.8.1.3 The pollutant dispersion from Trunk Road T2 and other roads within the 500m Study Area from Kai Tak to Cha Kwo Ling will be predicted using CALINE4 and ISCST3. For example, the broad approach to predict cumulative NO₂ levels is outlined below:

		Meteorological data		CALINE4	→	Cumulative NO_{2 (Road + Background)}
Background (EPD Kwun Tong Monitoring Station)	→	Conversion Factor of NO_x to NO₂	→			= (A)
		Background NO & NO₂		ISCST3	→	NO_{2 (Chimneys + Tunnel Portal + Ventilation Buildings, Typhoon Shelters, Kai Tak Development)} = (B)
Cumulative NO₂ _{(Road + Chimney + Tunnel Portal + Ventilation Building + Typhoon Shelters + Kai Tak Development + Background)} = (A) + (B)

4.8.1.4 The process for the operational air modelling is as follows and the detailed methodology and assumptions of each phase discussed in the sections below:

· format traffic figures;

· determination of the assessment year using EMFAC-HK;

· calculate the total vehicular tailpipe emissions from open roads and also tunnel portal and ventilation buildings within the Study Area from Kai Tak to Cha Kwo Ling using EMFAC-HK;

· use the meteorological data extracted provided by HKO (Year 2011) from Kai Tak Automatic Weather Station (including wind speed, wind direction and stability class), Hong Kong Observatory Manned Weather Station (including temperature and relative humidity) and King’s Park Automatic Weather Station (including mixing height) for input into the CALINE4 and ISCST3 models;

· use CALINE4 to assess air quality impacts from open roads; and

· use ISCST3 to assess air quality impacts from tunnel portals and ventilation buildings.

4.8.2 Traffic Figures

4.8.2.1 Summarised details of the traffic figures used in the air assessment have been provided in Section 3 of this report. The traffic figures have been approved for use in the EIA by Transport Department.

4.8.2.2 Hourly week day forecasts traffic flows, including a breakdown of sixteen vehicle categories, on the major roads related to the Trunk Road T2 project, as shown in Figures 4.3a and 4.3b, have been used for the EMFAC-HK v2.1 modelling for calculating the emission factors of roads for CALINE4 assessment of the open roads and the ISCST3 modelling for portal and ventilation shafts.

4.8.3 Determination of the Assessment Year

4.8.3.1 The air pollution impacts of future road traffic are typically calculated based on the highest emission strength from road vehicles within the first 15 years after commencement of operation of Trunk Road T2, that is, between 2021 and 2036. The assessment year is selected to represent the highest emission scenario, given the combination of vehicular emission factors and traffic flow for the selected year. As NO₂ is the pollutant of primary concern for a road project, the worst assessment year has be determined based on the highest NO_x emission scenario using the EMFAC-HK model.

4.8.3.2 Sensitivity tests have been conducted to determine the worst-case scenario given the combination of vehicular emission factors and the projected traffic flow for the following selected years within 15 years after the commencement of Trunk Road T2.

4.8.3.3 The representative years are 2021 (commencement of operation), 2026 and 2036 (15 years after commencement of operation). Emission factors in the year with the highest emission inventory have been used as the model year for the worst-case scenario prediction.

4.8.4 Determination of Vehicular Emissions from Open Roads

Background

4.8.4.1 The cumulative air quality impact generated by vehicular gaseous emissions from open road sections and tunnel portals would be calculated based on the highest emission strength given by the combination of traffic flow and vehicle mixture in the assessment year. EMFAC-HK v2.1 provided on EPD’s website, has been adopted to determine the emission inventories for this Trunk Road T2 air quality assessment as this was the version available at the time of the modelling. The latest model version EMFAC-HK v2.5.1 was released by EPD in early January 2013. As concluded in the “Outline of Changes in January 2013 Release of EMFAC-HK” in EPD’s website, the overall effects on emission estimates are insignificant, with only some changes in the output file formats due to items removal as comparing with v2.1. Besides, one output file name is also changed and the format for input files is changed from VKT to VMT to ensure the consistency in units used in input files (US units). The above format changes would not impose any change in the emission rate. Therefore, the vehicular tailpipe emission rates generated from v2.1 are still adopted in this assessment. These results would be input into CALINE4 for modelling of open road source dispersion and ISCST3 for portal and ventilation building emission modelling.

4.8.4.2 The detailed procedures and assumptions for the EMFAC-HK modelling have been derived in accordance with EPD’s Guideline on Modelling Vehicle Emissions and are discussed below.

Vehicle Classes

4.8.4.3 All vehicles operating on roads included in the assessment have been categorised into 16 vehicle classes in accordance with Appendix I of EMFAC-HK Guideline as shown in Table 4.9 below.

Table 4.9 Vehicle Classification in EMFAC-HK

Index	Vehicle Class Description	EMFAC Code	Gross Vehicle Weight
1	Private Cars (PC)	PC	ALL
3	Taxi	Taxi	ALL
4	Light Goods Vehicles (<= 2.5t)	LGV3	<=2.5t
5	Light Goods Vehicles (2.5 – 3.5t)	LGV4	>2.5-3t
6	Light Goods Vehicles (3.5 – 5.5t)	LGV6	>3.5-5.5t
7	Medium & Heavy Goods Vehicles (5.5 – 15t)	HGV7	>5.5-15t
8	Medium & Heavy Goods Vehicles (>=15t)	HGV8	>15t
11	Public Light Buses	PLB	ALL
12	Private Light Buses (<=3.5t)	PV4	<=3.5t
13	Private Light Buses (>3.5t)	PV5	>3.5t
14	Non-franchised Buses (<6.4t)	NFB6	<=6.36t
15	Non-franchised Buses (6.4 – 15t)	NFB7	>6.36-15t
16	Non-franchised Buses (>15t)	NFB8	>15t
17	Single Deck Franchised Buses	FBSD	ALL
18	Double Deck Franchised Buses	FBSD	ALL
19	Motor Cycles	MC	ALL

Road Groupings

4.8.4.4 Roads within the Study Area were grouped into eight sections based on the road types and the speed limit shown in Table 4.10. The roads were characterised by continuous flow and interrupted flow respectively. Eight sets of emission factors for the road types in each year were calculated. The associated Road Link Map is shown in Figures 4.4a and 4.4b.

Table 4.10 Road Grouping

Road Grouping	Road Types	Description
Type 1 Speed limit of 50 kph	Primary Distributor	Roads with speed limit of 50 kph and with no frontage access. Usually 24 hour stopping restrictions.
Type 2 Speed limit of 50 kph	District Distributor	Roads with speed limit of 50 kph and with junctions, pedestrian crossing and bus stop, etc. Usually peak hour stopping restrictions and parking restrictions throughout the day.
Type 3 Speed limit of 50 kph	Local Distributor	Roads with speed limit of 50 kph and with capacity limited by waiting vehicles and etc.
Type 4 Speed limit of 70 kph	Expressway	Roads are designated as Expressways under the Road Traffic (Expressway) Regulations. High capacity roads with no frontage access or development, pedestrians segregated, widely spaced grade separated junctions. 24 hour stopping restrictions.
Type 5 Speed limit of 70 kph	Urban Trunk	Roads connect the main centres of population. High capacity roads with no frontage access or development, pedestrians segregated, widely spaced grade separated junctions. 24 hour stopping restrictions.
Type 6 Speed limit of 80 kph	Expressway	Roads are designated as Expressways under the Road Traffic (Expressway) Regulations. High capacity roads with no frontage access or development, pedestrians segregated, widely spaced grade separated junctions. 24 hour stopping restrictions.
Type 7 Speed limit of 80 kph	Urban Trunk	Roads connect the main centres of population. High capacity roads with no frontage access or development, pedestrians segregated, widely spaced grade separated junctions. 24 hour stopping restrictions.
Type 8 Speed limit of 80 kph	Tunnel	Tunnel.

Exhaust Technology Fractions

4.8.4.5 The underlying assumptions of EMFAC-HK (v2.1) are that vehicles can be categorised into unique technology groups with each technology group representing vehicles with distinct emission control technologies, which have similar in-use deterioration rates, and respond the same to repair.

4.8.4.6 The Exhaust Technology Fraction for each vehicle class has been adopted from the information provided in the “2010 Vehicle Licensed Number by Age and Technology Group Fractions” from the EPD’s website. EMFAC-HK v2.1 has already included, as a default. All the existing vehicle emission control programmes. The implementation dates of the emission standards for various vehicle classes have been adopted in accordance with Appendix II of the EMFAC-HK Guideline.

4.8.4.7 Since the proposed Trunk Road T2 development involves no additional emission control programme, default values of exhaust technology fractions are considered as representative for this assessment.

Evaporative Technology Fractions

4.8.4.8 Default values and compositions are adopted in this Study, in accordance to the EPD’s Guideline on Modelling Vehicle Emissions.

Vehicle Population

4.8.4.9 The vehicle population forecast function in EMFAC-HK (v2.1) is only for natural replacement and no policy change can be reflected in this function. As the proposed development will not change the age distribution of the vehicles, the default vehicle populations forecast in EMFAC-HK (v2.1) have been adopted.

Vehicle Accrual

4.8.4.10 Since there is an absence of forecast information in the model year, “Default values and compositions” have been adopted in accordance with the EMFAC-HK Guidelines.

Daily Trips

4.8.4.11 With reference to the EPD’s Guideline on Modelling Vehicle Emissions, the diurnal variation of daily trips has been used to estimate the cold start emission of petrol and LPG vehicles. Hence, trips involving vehicles other than petrol and LPG type vehicles have been assumed to be zero. Estimations on the number of trips for petrol and LPG type vehicles on different road sections have assumed based upon the details provided in the following sections.

Primary Distributor, Trunk Road, Expressway and Tunnel Sections

4.8.4.12 It is assumed that the number of trips on the trunk road sections, including Type 4 to Type 8, would be zero as no cold start would be reasonably expected on these road sections under normal circumstances.

District Distributor and Local Distributor

4.8.4.13 It is assumed that the number of trips would be equal to the number of cold starts in the road sections, including Type 1, Type 2 and Type 3. It is also assumed that the number of trips is directly proportional to Vehicle-Mile-Travelled (VMT) and that the pattern would be similar throughout the Hong Kong territory. The number of trips in the Trunk Road T2 study area has been estimated by multiplying VMT _{within
Study Area} and Trips per VMT _{within Hong Kong} as follows:

4.8.4.14 Trips per VMT _{within Hong Kong} have been calculated based on the default data of EMFAC-HK (v2.1), whereas VMT_{within Study Area} have been calculated by multiplying the number of vehicles by the length of road travelled in this study area. Corresponding trips per VMT are shown in Appendix 4D.

Vehicle Miles Travelled (VMT)

4.8.4.15 Vehicle-Mile-Travelled (VMTs) are inputted in the model to represent the total distance travelled on a typical weekday. The regional specific VMT have been calculated by multiplying vehicle flow by the road section length with reference to the Traffic Impact Assessment report that have been submitted to Transport Department (TD) under this Agreement.

4.8.4.16 Diurnal traffic pattern will be inputted to simulate the effect of different traffic pattern. In order to determine the proportion of estimated daily traffic flow variation, hourly traffic flows at Core Stations No. 1025, 3003, 3004, 3012, 3020, 3023 and 3027 were referred, as they are the nearest available core stations to the Study Area and directly interfaces with the Project, according to Annual Traffic Census 2008 by TD. Locations of the nearby core stations extracted from TD are shown in Figure 4.5, whereas the estimated VKT for the selected modelling years are shown in Appendix 4E.

Hourly Temperature and Relative Humidity Profile

4.8.4.17 According to the information provided by Hong Kong Observatory, the nearest meteorological station to the Trunk Road T2 project area is the Hong Kong Observatory Weather Station, with an anemometer height of 74m above mean sea level. The characteristics of the Hong Kong Observatory Weather Station are considered representative to the Trunk Road T2 Study Area for the AQIA and, thus, annual and monthly averaged hourly ambient temperature and relative humidity obtained from this station for the latest available year (2011) have been adopted in the EM-FAC modelling. The monthly averaged hourly temperature and relative humidity values are arithmetic means of the same hourly interval over each calendar month while the annual averaged hourly values are arithmetic means of the same hourly interval over the entire year. The meteorological data in year 2011 has been confirmed to be over 90% valid. The adopted values are shown in Appendix 4F.

Model Year

4.8.4.18 For the purpose of finding the worst scenario year, a sensitivity test of the emissions inventories for three years within 15 years after the commencement of the Project has been carried out. The emission factors for Year 2021 (the commissioning year), Year 2026 and Year 2036 (15 years after commissioning) have been calculated. Based on the emission control schemes in the test years with varied VMT of the corresponding years, three sets of emissions inventories with emission factors have been produced. Emission factors in the year with the largest emission inventory are used for this assessment for the worst-case scenario prediction associated with vehicular gaseous emissions.

4.8.4.19 The travelling speeds of the vehicles at the roads for Year 2021, 2026 and 2036 have been adopted with respect to the corresponding years, whereas the travelling speeds have been calculated based on the traffic flow of the corresponding year and volume/capacity (V/C) ratio.

Speed Fraction

4.8.4.20 Hourly travelling speeds have been calculated based for the traffic flows in each year in corresponding to the specific volume/capacity ratio of different road types. Emission factors of each vehicle type would be extracted from the RTL files in accordance to the corresponding travelling speed at each hour.

4.8.4.21 In the model, the same travelling speeds have been applied to all vehicles for each type to demonstrate the effect of using peak flow speed and design speed. However, the diurnal variation of VMT for each vehicle has, also, been considered in the travelling speed estimation. In addition, in the speed fraction estimations, MGV, HGV and buses have been assumed to travel at speeds not exceeding 70 kph on all roads.

Modelling Modes

Scenario Type

4.8.4.22 The “EMFAC Mode” of EMFAC-HK (v2.1) has been applied and this provides the hourly vehicular emissions according to the diurnal variations of vehicle-kilometre-travelled (VKT), trips, ambient temperature, relative humidity and speed.

Output Frequency

4.8.4.23 Hourly average emission factors were derived for the purpose of obtaining worst emission factor.

Calculation of Emission Factors

4.8.4.24 Emission factors have been extracted from RTL file of the model. In respect of the urban trunk road sections, only “Run Exhaust” has been considered as it characterises continuous flow, whereas both “Start Exhaust” and “Run Exhaust” have been considered for the urban local distributor and urban district distributor for the need to take into account cold start emissions. The “Start Exhaust” is confined to petrol vehicles only.

4.8.4.25 Generic emission factors for each vehicle categories in different temperature, relative humidity and speed have been directly extracted from the data files and composite emission factors calculated for each road section using 24 hours diurnal traffic flows.

4.8.4.26 The calculated hourly emission factors have been selected for use in the modelling of the open roads using CALINE4 and deriving the emissions from tunnel portal and ventilation stacks for subsequent modelling by ISCST3. The estimated emission factors and emission inventories for years 2021, 2026 and 2036 are shown in Appendix 4G.

4.8.5 Meteorological Data

4.8.5.1 As mentioned in Section 4.7.3, the Year 2011 meteorological data from HKO will be assumed in the CALINE4 and ISCST3 models as follows:

· Wind speed: hourly record from the Kai Tak Weather Station meteorological data;

· Stability class: hourly record from the Kai Tak Weather Station meteorological data;

· Wind direction: hourly record from the Kai Tak Weather Station meteorological data;

· Directional variability: calculated according to the stability class; (Stability Class A, Standard Deviation of Wind Direction (sA) = 22.5^o; Stability Class B, sA = 22.5^o; Stability Class C, sA = 17.5^o; Stability Class D, sA = 12.5^o; Stability Class E, sA = 7.5^o; Stability Class F, sA = 3.8^o; A surface roughness factor of (z0/15 cm)0.2 was adopted where z0 is the surface roughness in cm);

· Mixing Height: hourly record from the King’s Park Weather Station meteorological data;

· Temperature: hourly record from the HKO Weather Station meteorological data; and

· Surface roughness: 100cm.

4.8.5.2 In respect of calm conditions where wind speed are 1.0 m/s or less, wind speeds have been assumed to be a minimum of 1.0 m/s in accordance with “Guideline on Air Quality Models Version 05”.

4.8.5.3 For the hourly meteorological data which is not available, the results of the related hours have not been considered.

4.8.6 Impact Modelling from Open Roads

4.8.6.1 The modelling of impacts from open stretches of road has been undertaken using the CALINE4 model. The hourly emission rates of each vehicle class (in grams per mile per vehicle) have been determined by dividing the emissions of the various road categories calculated with the EMFAC-HK model by the hourly traffic flow and the distance travelled. The composite emission factors in CALINE4 model have then been calculated.

4.8.6.2 In view of the constraints of the CALINE4 model in modelling elevated roads higher than 10m, the road heights of elevated road sections in excess of 10m high above local ground or water surface, such as the viaduct of Kwun Tong Bypass, have been set to 10m in the CALINE4 model as a worst-case assumption.

4.8.6.3 No noise barriers are proposed for the Trunk Road T2 project, Section 5, and no vertical barriers have been proposed for any of the concurrent projects. A noise enclosure specified for the TKO-LTT interchange is discussed in Section 4.8.7 below.

4.8.6.4 The Ambient Ratio Method (ARM) has been adopted for the conversion of NO_x to NO₂ for all vehicle emissions, which is assumed to be 20%.

4.8.6.5 Due to the potential for high rise buildings, the air quality impacts at 1.5m, 5m, 10m, 15m and 20m above local the ground level have been modelled for the South Apron and Cha Kwo Ling areas at the representative ASRs as a worst case scenario.

4.8.6.6 In addition, the cumulative impact of emissions from the open roads of existing roads in the area, the Kai Tak Development, CKR, TKO-LTT and Roads D3a and D4a have, also, been assessed and the emission factors of the roads have been obtained from results of EMFAC-HK model.

4.8.7 Determination of Emissions from Tunnel Portals and Vent Shafts

4.8.7.1 Emissions for tunnel portals and the ventilation buildings of the Trunk Road T2 have been be modelled using ISCST3. The hourly emissions inside the tunnels have been calculated by multiplying the emission strength (g/km/veh), obtained by the EMFAC-HK modelling above, for the worst case year, by the product of the traffic flow (veh/hr) and the tunnel length (km). Two tunnel ventilation buildings with vertical discharge are proposed for the Trunk Road T2 project, one on the south apron and one at Cho Kwo Ling, as shown in Figure 3.4. It has been assumed that the emission split would be 10% from tunnel portals and 90% from the vent shafts. This split has been based upon the potential for air quality impacts based upon the existing poor air quality in the area, proximity of sensitive receivers and to be consistent with recent tunnel designs of the Hong Kong Boundary Crossing Facilities (HKBCF), Tuen Mun – Chek Lap Kok Link (TM-CLKL) and what would be proposed for the TKO-LTT.

4.8.7.2 Emissions from the vent shafts have been assessed by ISCST3 model as volume sources with horizontal discharge in all directions. The data for the ventilation buildings are detailed in Appendix 4H.

4.8.7.3 Portal emissions have been modelled by ISCST3 and assessed in accordance with the Permanent International Association of Road Congress Report (PIARC, 1991). The emissions have been assumed to be discharged as a portal jet such that two-third of the total emission dispersed within first 50m of the portal and the remaining one-third of the total emission within the second 50m in the direction of the vehicular movements. The total emissions have been apportioned into volume sources as recommended by the PIARC guideline.

4.8.7.4 The Ambient Ratio Method (ARM) of 20% has been adopted for the conversion of NO_x to NO₂ for all vehicle emissions.

4.8.7.5 The air quality impacts at 1.5m, 5m, 10m, 15m and 20m above local ground level at representative ASRs have been assessed in the study to determine the worst case scenario.

4.8.7.6 Similar to the open road traffic emission using CALINE4 model for open roads, the ISCST3 model for the pollutant dispersion from tunnel portals and ventilation buildings has adopted real meteorological data, including temperature, wind speed and direction, stability class and mixing height extracted from the HKO.

4.8.7.7 As the tunnel portal and ventilation building of CKR are outside Trunk Road T2 500m study area, the emissions of them would not be included in the assessment. However, the emissions of the tunnel sections of Slip Road S3 and Trunk Road T2 ring roads assessed in the EIA report of CKR have been referred and assessed by ISCST3 in this assessment as they are within 500m study area of the Trunk Road T2. The information is detailed in Appendix 4I.

4.8.7.8 The emissions from the tunnel portals and ventilation buildings for the concurrent projects, including the TKO-LTT and the Eastern Harbour Tunnel, have, also, been modelled with ISCST3 and the assumptions for these projects are detailed in Appendices 4J and 4K respectively.

4.8.7.9 There are tunnel sections and enclosure proposed for the roads at the interchange of TKO-LTT at CKL and the emissions have been modelled by ISCST3 and the information is detailed in Appendix 4J.

4.8.8 Impact Modelling from Point Sources

4.8.8.1 In addition, the ISCST3 model will be used to calculate the emissions from back ground sources, namely the marine traffic that will use the Cruise Terminal, the proposed hospital chimney and the heliport of the Kai Tak Development, the chimneys at Kowloon Bay and Kwun Tong and the Kwun Tong Typhoon Shelter.

4.8.8.2 With reference to the EIA Report of Kai Tak Development, the assumptions with respect the above emission sources are detailed in the sections below.

Emissions from Cruise Terminal

4.8.8.3 A two-berth cruise terminal is proposed at the south west tip of the former Kai Tak runway. The major sources of cruise emission would be expected during manoeuvring and hotelling. In the EIA Report of Kai Tak Development (EIA-157/2008 approved on 4 March 2009), it was assumed that for each of the two berths within a 24 hour period in a day, the cruise vessel will perform the following movements:

· Berthing at the cruise terminal (for a period of 1 hour) - Berthing includes all the manoeuvring motions of the cruise vessel from the navigation channel to near the cruise terminal (for a period of 15 minutes), final manoeuvring around the berth (for a period of 15 minutes) and 30 minutes hotelling before connecting to / after disconnecting from the on-shore power supply if required. It is assumed that the berthing of two cruise vessels will not happen concurrently. Based on the vessel track simulation results, the entire manoeuvring motions of cruise vessels between the navigation channel and the berth would be completed within 30 minutes including the necessary turn and berth motions. Besides, with reference to a literature “Going Cold Iron in Alaska, R. Maddison & D.H. Smith”, connecting to on-shore power supply for vessels equipped with cold-ironing would normally be completed within 30 minutes; and

· Hotelling at the cruise terminal (for a period of 24 hours): If the cruise vessel is equipped with cold-ironing, it is assumed that the cruise vessel will be connected to the on-shore power supply within 30 minutes (as assumed during the one hour berthing period) and thus no air emissions will be generated during this hotelling period. On the other hand, if the cruise vessel is not equipped with cold-ironing, the cruise vessel will emit during its entire period of hotelling at the cruise terminal.

4.8.8.4 According to the sensitivity test of the above operation modes which had been done in the Schedule 3 EIA report, the results showed that the hotelling mode would be the dominant emission mode for cruise operation with regards to the potential air quality on the ASRs. Therefore, the above assumed cruise operation with 24 hours hotelling at the cruise terminal would result in a conservative assessment. For the hotelling scenario, the KTD Schedule 3 EIA assumed that there would be two tugboats for each cruise vessel and this approach has been adopted in the modelling.

4.8.8.5 With reference to the CKR EIA report, the “Study on Marin Vessels Emission Inventory, Final Report” published by EPD, is the latest information for marine emissions and, therefore, emission rates for the cruise terminal have been referenced from this report for the modelling. The details of emissions from the cruise terminal are provided in Appendix 4L.

4.8.8.6 The Ambient Ratio Method (ARM) of 20% has been adopted for the conversion of NO_x to NO₂ for the emissions from the cruise terminal.

Emissions from the Proposed Hospital Chimney

4.8.8.7 There are four hospitals proposed at the Area 3C in KTD. However, chimney emission data is only available for the CEP. The following emission factors and chimney diameters as adopted in the Schedule 3 EIA report of Kai Tak Development (March 2009) have been adopted for use in the operational phase assessment:

· Height of Chimney : 60m

· Fuel consumption : 600 L/hr

· Exit Velocity : 6m/s

· Temperature : 298K

· Diameter of Chimney : 0.5m

4.8.8.8 The data for the chimney are detailed in Appendix 4M. The Ambient Ratio Method (ARM) of 20% has been adopted for the conversion of NO_x to NO₂ for the emissions from the chimney.

Emissions from Heliport

4.8.8.9 A heliport is proposed at the end of former Kai Tak airport runway. The following emission factors, as adopted in the EIA report of Kai Tak Development, are assumed for use in this assessment. The emission rates adopted in the assessment are shown in Table 4.11 below.

Table 4.11 Emission Factors for Twin Engine T58-GE-8F

Helicopter Mode	NO_x (lb/min)	RSP (lb/min)
Approach (Approach + Hovering to Landing	0.098	0.027
Idling	0.006	0.003
Takeoff (Hovering to Take Off + Take Off	0.143	0.027

4.8.8.10 The information of the emissions of the helicopter is detailed in Appendix 4N. The Ambient Ratio Method (ARM) of 20% has been adopted for the conversion of NO_x to NO₂ for the emissions from the helicopter.

Kwun Tong Typhoon Shelter

4.8.8.11 According to the Schedule 3 EIA report of Kai Tak Development, there are two typhoon shelters in the Trunk Road T2 study area, which are located at Kwun Tong and To Kwa Wan. However, the To Kwa Wan Typhoon Shelter is outside the Trunk Road T2 500m study area and not included in this assessment.

4.8.8.12 The details of the emissions from the KTTS have made reference to the Trunk Road T2 marine traffic survey undertaken in 2009, as detailed below, and the Schedule 3 EIA report of the Kai Tak Development. The emissions from KTTS have been considered based upon the number of vessels observed by the Trunk Road T2 marine traffic surveys undertaken in 2009. In order to identify the frequency and distribution of vessel movements by time and type, a project specific 12-day marine traffic survey was conducted over a month, between 3 November 2009 to 3 December 2009, using a time-lapse camera sited at the North Point Government Office. The marine survey included the water space of the Kwun Tong Typhoon Shelter and the operations of the Kwun Tong Public Cargo Works Area (PCWA) and the Kerry Dangerous Goods Godown. The diagrammatic locations of the key marine traffic survey sites are shown in the figure in Appendix 4O.

4.8.8.13 The survey of the Kwun Tong Typhoon Shelter recorded the daily vessel movements to/from the typhoon shelter and vessels were categorised into twelve classes for the purposes of analysis, as detailed below:

a) Cargo Vessels: O-G Cargo;

Rivertrade;

Tug & Tow; and

Derrick Barge.

b) Passenger Vessels: O-G Passenger;

Fast Ferry;

Conventional Ferry; and

Fast Launch.

c) Others: Tugboat;

Fishing Vessels;

Local DG;

Pleasure Vessels; and

Unclassified.

4.8.8.14 The average traffic distribution recorded on a daily basis with respect each of the vessel types is presented in Table 4.12 below. It is identified that the major vessel movements of this area are Conventional Ferry contributing 49% of movements. The local Dangerous Good Vessels contribute another 19% to the total traffic volume.

Table 4.12 Daylight Average Marine Traffic Movements in Kwun Tong Entering/Leaving Typhoon Shelter (Visual Survey 2009)

Vessel Category	Vessel Type	Daylight Average Traffic Movements	Percentage Contribution (%)
Cargo	O-G Cargo	1*	0.4
	River Trade	17	9
	Tug & Tow	0*	0.2
	Derrick Barge	7	3
Passenger	O-G Passenger	0	-
	Fast Ferry	0	-
	Conventional Ferry	97	49
	Fast Launch	13	7
Others	Tugboat	1	1
	Fishing Vessel	4	2
	Local DG	39	19
	Pleasure Vessels	0	-
	Unclassified	19	9
TOTAL		198	100

Note* Figures are rounded up

4.8.8.15 In terms of air emissions, however, the relevant vessels movements are:

· Local Dangerous Good Vessels : 39 trips (20 vessels);

· Rivertrade and Barges: 24 trips (12 vessels); and

· Fast Launches: 13 trips (7 vessels).

4.8.8.16 However, it should be noted that the Kwun Tong PCWA was decommissioned in early 2012 to make way for the development of Kwun Tong Promenade and will no longer be in operation at the time of the first year of operation of the Trunk Road T2, that is, in year 2021. Similarly, the Kerry Godown Dangerous Goods Store has obtained planning permission to be rezoned as residential and the development will be completed towards the end of 2016. The remaining Dangerous Goods vessels are related to the DG pier located at the breakwater to the KTTS and 1km from the South Apron, with the vessels not passing through the KTTS. Therefore it is anticipated that no working craft will be navigating within the typhoon shelter during the operational phase of the Trunk Road T2.

4.8.8.17 Based on the above, the remaining number of major vessels to be anticipated as having a potential cumulative impact within the KTTS would be 7 fast launch vessels. Assuming a year-on-year increase in usage of such vessels of 6% from the survey year of 2009, the predicted number of major vessels operating in the KTTS would be 14. As a conservative estimate 20 vessels have been assumed to be operating within the KTTS for the purposes of this assessment. The emission factors from the vessels have been made reference from the “Study on Marin Vessels Emission Inventory, Final Report”.

4.8.8.18 The details of the emissions from the source are shown in Appendix 4O. A barge is used as the vessel to derive the emission factors as its auxiliary power is considered more conservative than that of a fast launch vessel. The Ambient Ratio Method (ARM) of 20% has been adopted for the conversion of NO_x to NO₂ for the emissions of vessels.

4.8.9 Determination of Cumulative Impacts

4.8.9.1 The predicted overall cumulative hourly average concentrations of NO₂ and RSP have been calculated by adding each predicted hourly result from CALINE4 (open roads) and each predicted hourly results from ISCST3 (emissions from the portals, ventilation buildings and chimneys, etc.) according to the time sequence of the results from CALINE4 and ISCST3 and then the background from EPD’s AQMS. The predicted overall cumulative 24-hour and annual average concentrations of NO₂ and RSP have been calculated from the overall cumulative hourly average concentrations of NO₂ and RSP.

4.8.10 In-tunnel Air Quality

4.8.10.1 It is the responsibility of the Applicant to ensure that the air quality inside the tunnel comply with EPD’s “Practice Note on Control of Air Pollution in Vehicle Tunnels”. The air quality inside the tunnel should meet the EPD recommended standard of 1pm NO₂ concentration. Air quality within the tunnel is to be monitored and the tunnel ventilation system is designed with the objective of removing/diluting vehicle emissions such that air quality inside will comply with stated air quality standards. Appendix 4T provides details on how the air pollutant concentrations within the proposed Trunk Road T2 tunnel are derived and addressed in this EIA study.

4.8.11 Level of Uncertainty

4.8.11.1 The emission rates adopted in the CALINE4 modelling are calculated by the EMFAC-HK model (V2.1) that more accurately predicts the emission rates than using EURO emission rates. Moreover, the inputs for the models have been prepared based on Guideline on Modelling Vehicle Emissions issued by EPD on April 2012.

4.8.11.2 The CALINE4 and ISCST3 models used for the modelling of the operational air quality impact assessment are the accepted models for calculating the air pollutants impacts for the roads and stationary sources and which have made reference to the Guidelines on Choice of Models and Model Parameters.

4.8.11.3 In addition, as the emission rate hourly profile is not available in the KTD Schedule 3 EIA report of the chimney of the Hospital, so the hourly emission rates of NO_x and RSP assumed in the KTD EIA report have been adopted and assumed as the same for each hour of a day in the assessment of this EIA report. Utilising this assumption has only made the approach of the assessment more conservative.

4.8.11.4 For the emissions from the cruise terminal, it is assumed that the two cruises would be in hotelling mode at the berths of the cruise terminal rather than in manoeuvring mode around the berths of the cruise terminal. However, this assumption has made the approach of assessment more conservative.

4.8.11.5 Uncertainties in the assessment of impacts have been considered when drawing conclusion from the assessment and worst case scenarios adopted.

4.9 Construction Air Quality Assessment

4.9.1 Unmitigated Results

4.9.1.1 The maximum predicted unmitigated 1-hour, 24-hour and annual average cumulative TSP levels, based upon the worst case 100% active works area for the short term predictions (1-hour and 24-hour) and 100% active area for the annual predictions, are presented in Table 4.13 below. The unmitigated 1-hour, 24-hour and annual average cumulative contours at 1.5m above ground are provided in Figures 4.6 to 4.11.

4.9.1.2 Based on the worst case assessment, the results show that exceedances of the relevant Air Quality Objectives (AQOs) are predicted to occur at all ASRs for the 1-hourly TSP. However, for the 24-hour TSP level, ASRs KB1, KB2, KB4 and KB5 would not be subject to exceedances. In terms of the annual results, KB1 to KB5 would not exceed the annual AQO standard of 80 µg/m³ but all other ASRs inKai Tak and Cha Kwo Ling would be subject to annual exceedances without mitigation measures applied. Therefore, mitigation measures are required to control dust impacts at all ASRs.

Table 4.13 1-hour, 24-hour and Annual Average Maximum Cumulative Unmitigated TSP Concentrations (µgm^-3) at ASRs (Including Background Level)

Receiver Reference	Predicted Maximum 1-hour Concentration (Standard 500 µg/m³)		Predicted Maximum 24-hour Concentration (Standard 260 µg/m³)	Predicted Maximum Annual Concentration (Standard 80 µg/m³)
KB1	1039		199	74.6
KB2	1387		256	75.8
KB3	1727		321	75.7
KB4	803		178	74.5
KB5	1030		253	74.8
KTD3	3988		642	85.4
KTD6	4530		1166	85.4
CKL1	2975		499	95.2
CKL2	2998		326	88.1
CKL3	4031		536	93.8
Note:		denotes TSP level in excess of criteria

4.9.2 Mitigation Measures

4.9.2.1 Specific mitigation measures have been assumed in the modelling to reduce the dust generation from the Trunk Road T2 project to within the 1-hour (500µgm^-3), 24-hour (260µgm^-3) and Annual (80µgm^-3) criteria at ASRs, and have been applied for both the short-term Tier 1 and annual TSP predictions. The specific mitigation comprises the following:

(i) watering of the construction areas 12 times per day to reduce dust emissions by 91.7%, with reference to the “Control of Open Fugitive Dust Sources” (USEPA AP-42). The amount of water to be applied would be 0.91L/m² for the respective watering frequency (Appendix 4A);

(ii) Dust enclosures with watering would be provided along the loading ramps and conveyor belts for unloading the C&D materials to the barge for dust suppression; and

(iii) 3-sided barriers around the stockpiling areas WA3 and WA4.

4.9.2.2 In addition to the mitigation mentioned above, under the auspices of the Air Pollution Control (Construction Dust) Regulation, the Contractor will be required to ensure that dust control measures stipulated in the Regulation should be implemented to control dust emissions. The dust control measures detailed below shall also be incorporated into the Contract Specification where practicable as an integral part of good construction practice:

(i) Use of regular watering to reduce dust emissions from exposed site surfaces and unpaved roads, particularly during dry weather;

(ii) Use of frequent watering for particularly dusty construction areas and areas close to ASRs;

(iii) Side enclosure and covering of any aggregate or dusty material storage piles to reduce emissions. Where this is not practicable owing to frequent usage, watering shall be applied to aggregate fines;

(iv) Open stockpiles shall be avoided or covered. Prevent placing dusty material storage piles near ASRs;

(v) Tarpaulin covering of all dusty vehicle loads transported to, from and between site locations;

(vi) Establishment and use of vehicle wheel and body washing facilities at the exit points of the site;

(vii) Imposition of speed controls for vehicles on unpaved site roads, 8 km per hour is the recommended limit;

(viii) Routing of vehicles and position of construction plant should be at the maximum possible distance from ASRs;

(ix) Every stock of more than 20 bags of cement or dry pulverised fuel ash (PFA) should be covered entirely by impervious sheeting or placed in an area sheltered on the top and the 3 sides;

(x) Cement or dry PFA delivered in bulk should be stored in a closed silo fitted with an audible high level alarm which is interlocked with the material filling line and no overfilling is allowed; and

(xi) Loading, unloading, transfer, handling or storage of bulk cement or dry PFA should be carried out in a totally enclosed system or facility, and any vent or exhaust should be fitted with an effective fabric filter or equivalent air pollution control system.

4.9.3 Mitigated Results

Short Term Dust Predictions

4.9.3.1 The maximum predicted 1-hour and 24-hour averaged results of the Tier 1 screening at representative ASRs in the study area with mitigation measures applied are shown in Table 4.14 below. The mitigated Tier 1 screening test 1-hour and 24-hour averaged cumulative (Trunk Road T2, CKR, TKO-LTT, Roads D3a and D4a + other concurrent projects + background) contours at 1.5m above ground are shown in Figures 4.12 to 4.15. The sample calculation of the results is shown in Appendix 4Q.

Table 4.14 Tier 1 Screening Test: 1-hour and 24-hour Averaged Maximum Cumulative TSP Concentrations (µg/m³) at ASRs (Including Background Level)

Receiver Reference	Predicted Maximum 1-hour Concentration (Criterion: 500µg/m³)		Predicted Maximum 24-hour Concentration (Criterion: 260µg/m³)
KB1	155		86
KB2	195		94
KB3	232		100
KB4	164		86
KB5	174		90
KTD3	399		126
KTD6	451		169
CKL1	351		115
CKL2	432		107
CKL3	570		136
Note:		denotes TSP level in excess of criterion

4.9.3.2 The results indicate that ASR CKL3 at Cha Kwo Ling would be subject to exceedances of the 1-hour TSP criteria when assuming the absolute worst case situation where 100% of every works site would be active and emitting dust. There are no exceedances predicted for other ASRs. However, according to the contour plots of the 1-hour average results (Figure 4.12 and Figure 4.13), there are two areas with exceedances at Kai Tak area and one area in Cha Kwo Ling area. For the area with exceedance in Kai Tak along the South Apron, the area comprises the Trunk Road T2 works areas and CKR works areas and no sensitive receivers are present in that area. For the area with exceedance at Kai Tak at the end of South Apron, the area comprises the Trunk Road T2 works areas and no sensitive receivers are present in that area. Therefore, it is concluded that the dust impacts at Kai Tak area is not significant such that a Tier 2 assessment at Kai Tak area is not required. However, for the area with an exceedance at Cha Kwo Ling, although most of the coverage of the area with exceedance is the works areas of TKO-LTT, some sensitive receivers (including ASR CKL3 and the industrial area at the waterfront of CKL) are present within the area and, therefore, a Tier 2 assessment has been undertaken, as detailed below. For the contour plot of the 24-hour averaged TSP results (Figure 4.14 and Figure 4.15), there are no exceedances observed in the Kai Tak area. However, there is an area of exceedance at Cha Kwo Ling which mainly comprises the works sites of TKO-LTT where no ASRs are located. Therefore, it is concluded that the dust impacts are considered as insignificant for the 24-hour averaged TSP results.

4.9.3.3 At Cha Kwo Ling, the source of construction dust emissions from the Trunk Road T2 project comprises the excavation of the TBM receiving shaft at the Cha Kwo Ling PCWA, which comprises two excavation zones of about 130m long by 22.5m wide and 35.5m long by 25.5m wide, respectively. In contrast, the construction works site of the TKO-LTT project, which is about 500m long by 350m wide, and as such the predicted emission of construction dust originated from Trunk Road T2 project would be very minor. Table 4.15 shows the contribution of construction dust from the Trunk Road T2 project compared with the concurrent TKO-LTT project.

Table 4.15 Contribution of Construction Dust Impact at CKL3 by Various Projects (Excluding Background Level)

ASR Receiver Reference	Contribution from Trunk Road T2 Project (µg/m³)	Contribution from Concurrent Project (µg/m³)	Predicted Maximum 1-hour Concentration (Criterion: 500µg/m³)
CKL3	5.6	491.7	497.3

ASR Receiver Reference

Contribution from Trunk Road T2 Project

(µg/m³)

Contribution from Concurrent Project

(µg/m³)

Predicted Maximum 1-hour Concentration

(Criterion: 500µg/m³)

CKL3

5.6

491.7

497.3

4.9.3.4 It is observed that the contribution from the Trunk Road T2 project is very minor, contributing only 1.1% of the total construction dust impact at CKL3, and, hence, the exceedance is largely caused by concurrent TKO-LTT project.

4.9.3.5 In addition, as Cha Kwo Ling PCWA is a construction works site shared by both the Trunk Road T2 project and the TKO-LTT project, in the TKO-LTT EIA report, emissions from both projects at the Cha Kwo Ling PCWA have been included. Thus, in assessing the cumulative impacts and assuming the works areas of both the Trunk Road T2 and TKO-LTT project are operating concurrently, the emissions from the Trunk Road T2 portion of the works have been included in the assessment twice by extracting the Trunk Road T2 and TKO-LTT project emissions from the TKO-LTT EIA but, also, assessing the Trunk Road T2 site emissions separately. In reality, this would not occur and hence, it should be noted that the assessment is overly pessimistic.

4.9.3.6 Notwithstanding, a focused Tier 2 assessment has been undertaken and assumed that dust emissions would occur from a 30 % active area as opposed to 100% of the Cha Kwo Ling whole site. The justification of the percentage is presented in Appendix 4A. As noted above sections, this would also represent a very conservative scenario and would be an over prediction of what the actual dusts emissions that would be expected to occur. All the mitigation measures applied for the Tier 1 assessment have, also, been included in the Tier 2 assessment.

4.9.3.7 The maximum predicted 1-hour and 24-hour results, for the representative ASR CKL3 for the Tier 2 focused Cha Kwo Ling assessment area, are presented in Table 4.16. The results show that the Tier 2 1-hour and 24-hour TSP levels at CKL3 are below the relevant AQOs. The Tier 2 contour plots of the 1-hour and 24-hour averaged TSP results are shown in Figures 4.16 and 4.17. According to the contour plot of the 1-hour averaged TSP results, there is an area with exceedance at CKL. However, this area comprises the works areas of the TKO-LTT project and the existing roads. Therefore, it is concluded that the dust impact is not significant. For the contour plot of the 24-hour averaged TSP results, there is a small area with exceedance but this comprises the works areas of the TKO-LTT project where no ASRs are located. Therefore, it is concluded that the dust impacts are considered as insignificant.

Table 4.16 Tier 2 Focused Cha Kwo Ling Assessment: 1-hour and 24-hour Maximum Cumulative TSP Concentrations (µg/m³) at ASRs (Including Background Level)

Receiver Reference	Predicted Maximum 1-hour Concentration (Criterion: 500µg/m³)		Predicted Maximum 24-hour Concentration (Criterion: 260µg/m³)
CKL3	394		124
Note:		denotes TSP level in excess of criterion

Long Term Dust Predictions

4.9.3.8 The maximum predicted annual average TSP concentrations at representative ASRs in the study area with mitigation measures applied are shown in Table 4.17. The mitigated annual averaged cumulative (Trunk Road T2, CKR, TKO-LTT, Roads D3a and D4a + other concurrent projects + background) contours at 1.5m above ground, are provided in Figures 4.18 to 4.19.

Table 4.17 Annual Average Maximum Cumulative TSP Concentrations (µg/m³) at ASRs (Including Background Level)

Receiver Reference	Predicted Maximum Annual Average Concentration (Criterion: 80µg/m³)
KB1	73.4
KB2	73.6
KB3	73.5
KB4	73.3
KB5	73.3
KTD3	74.6
KTD6	74.5
CKL1	76.5
CKL2	75.4
CKL3	76.3
Note:		denotes TSP level in excess of criterion

4.9.3.9 The predicted maximum cumulative annual averaged TSP concentrations at representative ASRs detailed in Table 4.17 indicate that all ASRs are in full compliance with the annual criteria. According to the contour plots for the annual averaged cumulative TSP levels (Figures 4.18 to 4.19), there is an area with exceedance. However, this area comprises the works areas of the TKO-LTT project. Therefore, it is concluded that the dust impacts are insignificant_.

4.9.3.10 Given that recommended measures are tried and tested techniques used extensively throughout Hong Kong construction projects, the level of uncertainty of their effective implementation would be small. Notwithstanding, the EM&A programme will be implemented to ensure all mitigation measures are effective.

4.9.4 Residual Impacts

4.9.4.1 The residual impacts refer to the net impacts after mitigation, taking into account the background environmental conditions and the impacts from existing, committed and planned projects.

4.9.4.2 Residual air quality impacts associated with the construction of the Trunk Road T2 project have been assessed. It is concluded that residual impacts would not be significant being of short duration, occurring for the construction phase only and the main construction dust sources are from the TKO-LTT project works areas in Cha Kwo Ling. Although the whole period of construction for the Trunk Road T2 project will be 61 months, with the exception of the work areas for the open cut and the stockpile areas, the construction activities, overall, will be of short duration, localised and confined to small areas around the works sites at a time.

4.9.4.3 In addition, with the proposed mitigation measures, the impacts from the construction activities will be considered as not significant, even though a worst case assessment assuming all the construction works would be carried concurrently has been undertaken. Therefore, construction dust is not predicted to affect the health and welfare of the local community or any agricultural activities and no irreversible adverse environmental impacts will be anticipated.

4.10 Operational Air Quality Assessment

4.10.1 Assessment Year

4.10.1.1 Emission factors have been determined using the EMFAC-HK model V2.1 for three different years, namely 2021, 2026 and 2036, to determine the worst case assessment year for further assessment and the details provided in Appendix 4G. Composite emission factors for the road links of the Trunk Road T2 project have been calculated using the weighted average of the emission factors of the sixteen vehicle types. Details of the sensitivity analysis are shown in Appendix 4P and Tables 4.18 and 4.19 below for the greatest emission inventory results for Nitrous Oxides (NO_x) and Respirable Suspended Particulates (RSP) in Year 2021, respectively.

Table 4.18 Sensitivity Test of Emission Inventories for NO_x Emissions

NO_x Emissions (ton/Day)	Yr 2021	Yr 2026	Yr 2036
Type 1 Speed 50	0.1855	0.1219	0.0687
Type 2 Speed 50	0.3101	0.2040	0.1238
Type 3 Speed 50	0.1587	0.0981	0.0533
Type 4 Speed 70	0.0457	0.0260	0.0137
Type 5 Speed 70	0.1047	0.0650	0.0380
Type 6 Speed 80	0.2471	0.1406	0.0742
Type 7 Speed 80	0.0585	0.0357	0.0215
Type 8 Speed 80	0.0175	0.0113	0.0073

Table 4.19 Sensitivity Test of Emission Inventories for RSP Emissions

RSP Emissions (ton/Day)	Yr 2021	Yr 2026	Yr 2036
Type 1 Speed 50	0.0079	0.0055	0.0037
Type 2 Speed 50	0.0155	0.0101	0.0065
Type 3 Speed 50	0.0111	0.0062	0.0031
Type 4 Speed 70	0.0025	0.0020	0.0014
Type 5 Speed 70	0.0045	0.0036	0.0026
Type 6 Speed 80	0.0147	0.0119	0.0086
Type 7 Speed 80	0.0028	0.0023	0.0017
Type 8 Speed 80	0.0007	0.0006	0.0005

4.10.1.2 Table 4.18 and Table 4.19 show that the greatest emission inventory for NO_x and RSP is in the Year 2021 and, therefore, Year 2021 has been selected as the worst case model year for the air quality impact assessment.

4.10.2 Emission Factors

4.10.2.1 As noted above, Year 2021 has been selected as representing the worst case year for assessment. As such, all modelling has used the emission factors from 2021 to determine the impacts on sensitive receivers. The calculated emission factors for the roads for NO_x and RSP of Year 2012 are detailed in Appendix 4R.

4.10.3 Cumulative Modelling Results

4.10.3.1 During the operational phase, the predicted maximum overall hourly, 24-hour and annual averaged NO₂ and RSP concentrations have been calculated as described in above from combining the following results:

(i) predicted concentrations of background sources derived from a 5 year annual average of EPD AQMS;

(ii) supplementary background sources calculated by ISCST3 (including the emissions from chimneys, marine vessels and the heliport);

(iii) open road emissions calculated using CALINE4, including Trunk Road T2, existing roads and, also, the emissions from the open roads of the concurrent projects of CKR and TKO-LTT; and

(iv) emissions from the tunnel portals and ventilation buildings derived from ISCST3 for each hour at each sensitive receiver for the Trunk Road T2, TKO-LTT, CKR and the Eastern Harbour Tunnel.

4.10.3.2 The predicted results at the ASRs at 1.5m, 5m, 10m, 15m and 20m above ground, are shown in Table 4.20 below. The sample calculation of the results is shown in Appendix 4S.

Table 4.20 Predicted Maximum Overall Hourly, 24-hour and Annual NO₂ and RSP Concentrations (µg/m³) at ASRs (including background levels)

ASR Ref.	Height Above Ground (m)	NO₂(µg/m³)			RSP(µg/m³)
ASR Ref.	Height Above Ground (m)	1-hour (300 (µg/m³)	24-hour ( 150µg/m³)	Annual (80µg/m³)	24-hour (180 (µg/m³)	Annual (55µg/m³)
KB1	1.5	167	90	70.1	59	51.7
KB2	1.5	199	95	71.5	61	52.2
KB3	1.5	167	94	72.3	60	52.5
KB4	1.5	168	93	72.6	61	52.6
KB5	1.5	156	90	72.2	60	52.7
KTD1	1.5	174	87	73.9	59	53.0
KTD2	1.5	175	86	74.7	59	53.3
KTD3	1.5	131	85	70.6	60	52.6
KTD4	1.5	130	88	71.6	62	53.2
KTD5	1.5	166	89	71.3	60	53.3
KTD6	1.5	165	87	69.1	61	52.5
KTD7	1.5	133	86	69.0	61	52.6
KTD8	1.5	123	82	67.1	59	51.3
KTD9	1.5	114	76	65.7	56	51.1
CKL1	1.5	164	80	66.8	57	50.9
CKL2	1.5	167	78	66.0	56	50.7
CKL3	1.5	157	75	65.8	55	50.6
CKL4	1.5	142	83	71.7	57	52.4
CKL5	1.5	164	76	64.5	56	50.2
CKL6	1.5	137	80	64.5	57	50.2
KB1	5	159	87	68.6	59	51.3
KB2	5	196	92	70.6	60	52.0
KB3	5	163	90	71.0	59	52.1
KB4	5	161	90	70.5	61	52.1
KB5	5	160	92	73.0	60	52.9
KTD1	5	165	86	72.3	59	52.6
KTD2	5	164	83	72.7	59	52.7
KTD3	5	131	85	69.8	60	52.4
KTD4	5	128	88	71.2	61	53.0
KTD5	5	149	85	70.5	60	52.9
KTD6	5	164	87	69.0	61	52.4
KTD7	5	133	86	68.9	61	52.5
KTD8	5	123	82	67.0	59	51.3
KTD9	5	115	76	65.7	56	51.1
CKL1	5	153	78	65.6	56	50.6
CKL2	5	163	77	65.5	56	50.5
CKL3	5	157	75	65.5	55	50.5
CKL4	5	127	78	67.5	56	51.1
CKL5	5	164	76	64.4	56	50.1
CKL6	5	137	79	64.2	56	50.1
KB1	10	151	84	66.8	58	50.9
KB2	10	188	89	69.3	59	51.7
KB3	10	154	87	69.5	58	51.8
KB4	10	152	86	68.4	60	51.5
KB5	10	155	90	71.9	60	52.6
KTD1	10	150	84	70.2	59	52.0
KTD2	10	144	82	70.0	58	52.0
KTD3	10	130	84	68.6	60	52.0
KTD4	10	126	86	69.8	61	52.5
KTD5	10	128	83	68.7	60	52.2
KTD6	10	158	86	68.6	61	52.2
KTD7	10	133	85	68.4	61	52.3
KTD8	10	124	82	66.8	59	51.3
KTD9	10	117	76	65.7	56	51.1
CKL1	10	136	75	64.2	55	50.1
CKL2	10	154	75	64.5	56	50.2
CKL3	10	154	75	64.6	55	50.2
CKL4	10	119	75	64.5	55	50.2
CKL5	10	164	76	64.2	56	50.1
CKL6	10	148	77	63.6	56	49.9
KB1	15	149	82	65.9	58	50.7
KB2	15	179	86	68.1	59	51.3
KB3	15	147	84	68.3	58	51.4
KB4	15	148	84	67.3	59	51.2
KB5	15	142	85	69.4	59	51.9
KTD1	15	139	83	68.9	58	51.6
KTD2	15	130	81	68.4	58	51.6
KTD3	15	129	82	67.6	59	51.7
KTD4	15	125	84	68.3	60	51.9
KTD5	15	126	83	67.5	59	51.7
KTD6	15	148	85	67.9	61	51.9
KTD7	15	133	84	67.8	60	52.0
KTD8	15	126	83	66.5	59	51.2
KTD9	15	119	77	65.6	57	51.1
CKL1	15	131	73	63.7	54	49.9
CKL2	15	148	74	63.8	55	50.0
CKL3	15	152	74	63.8	55	50.0
CKL4	15	120	73	63.8	55	50.0
CKL5	15	164	76	64.0	56	50.0
CKL6	15	171	75	63.2	55	49.8
KB1	20	148	81	65.3	57	50.5
KB2	20	173	83	66.8	58	51.0
KB3	20	142	81	67.2	57	51.1
KB4	20	145	83	66.5	59	50.9
KB5	20	135	84	67.8	59	51.4
KTD1	20	137	80	67.9	57	51.3
KTD2	20	131	78	67.2	56	51.3
KTD3	20	108	76	66.7	56	51.3
KTD4	20	110	78	67.0	57	51.4
KTD5	20	105	76	66.6	56	51.3
KTD6	20	137	78	67.0	56	51.5
KTD7	20	107	76	66.8	56	51.6
KTD8	20	128	83	66.1	59	51.1
KTD9	20	123	78	65.4	57	51.0
CKL1	20	132	73	63.4	54	49.8
CKL2	20	148	74	63.3	55	49.8
CKL3	20	151	74	63.3	55	49.8
CKL4	20	122	72	63.4	54	49.8
CKL5	20	165	76	63.7	56	49.9
CKL6	20	181	75	62.9	55	49.7

Note: Shaded cell denotes exceedance of relevant AQO.

4.10.3.3 The results show that that both pollutants are within the AQOs at all designated ASRs.

4.10.3.4 These results are, also, expressed as contour plots which can be seen in Figures 4.20 to 4.23 for the hourly average concentrations of NO₂, Figures 4.24 to 4.31 for 24-hour average concentrations of NO₂ and RSP respectively, and Figures 4.32 to 4.37 for the annual average concentrations of NO₂ and RSP respectively. The contour plots, also, indicate that no sensitive areas will exceed the relevant AQOs.

4.10.3.5 The contribution to the cumulative values from the Trunk Road T2 project alone is relatively small, as shown in Tables 4.21a, b and c for the 1-hour, 24 hour and annual NO₂, and Tables 4.22a and b for the 24 hour and annual RSP values, respectively.

Table 4.21a Breakdown of 1-Hour NO₂ Contributions (µg/m³ and Percentage)

ASR	Amount of Contribution of 1-Hour Average NO₂ Concentration, µg/m³(AQO = 300 µg/m³)				% of Contribution
ASR	Overall Cumulative	Back-ground	Other Sources	Trunk Road T2	Back-ground	Other Sources	Trunk Road T2
KB1	167.2	60.4	106.6	0.1	36.1%	63.8%	0.1%
KB2	198.7	60.4	135.2	3.1	30.4%	68.0%	1.6%
KB3	167.4	60.4	106.9	0.0	36.1%	63.9%	<0.1%
KB4	168.5	60.4	108.1	0.0	35.9%	64.1%	<0.1%
KB5	156.3	60.4	94.9	1.0	38.7%	60.7%	0.7%
KD1	174.4	60.4	113.1	0.9	34.6%	64.9%	0.5%
KD2	175.1	60.4	99.3	15.4	34.5%	56.7%	8.8%
KD3	131.2	60.4	70.5	0.2	46.0%	53.8%	0.2%
KD4	130.3	60.4	69.9	0.0	46.4%	53.6%	<0.1%
KD5	166.1	60.4	105.7	0.0	36.4%	63.6%	<0.1%
KD6	165.5	60.4	105.1	0.0	36.5%	63.5%	<0.1%
KD7	132.6	60.4	72.0	0.2	45.5%	54.3%	0.2%
KD8	123.2	60.4	62.8	0.0	49.0%	51.0%	<0.1%
KD9	114.4	60.4	54.0	0.0	52.8%	47.2%	<0.1%
CKL1	163.5	60.4	103.1	0.0	36.9%	63.1%	<0.1%
CKL2	167.2	60.4	106.8	0.0	36.1%	63.9%	<0.1%
CKL3	157.2	60.4	96.8	0.0	38.4%	61.6%	<0.1%
CKL4	141.5	60.4	81.1	0.0	42.7%	57.3%	<0.1%
CKL5	163.8	60.4	103.4	0.0	36.9%	63.1%	<0.1%
CKL6	137.0	60.4	76.6	0.0	44.1%	55.9%	<0.1%

Table 4.21b Breakdown of 24-Hour NO₂ Contributions (µg/m³ and Percentage)

ASR	Amount of Contribution of 24-Hour Average NO₂ Concentration, µg/m³ (AQO = 150 µg/m³)				% of Contribution
ASR	Overall Cumulative	Back- ground	Other Sources	Trunk Road T2	Back-ground	Other Sources	Trunk Road T2
KB1	89.8	60.4	29.1	0.3	67.3%	32.4%	0.4%
KB2	94.9	60.4	34.2	0.3	63.6%	36.1%	0.3%
KB3	93.6	60.4	32.4	0.8	64.5%	34.6%	0.9%
KB4	93.5	60.4	33.0	0.0	64.6%	35.3%	<0.1%
KB5	90.5	60.4	29.9	0.2	66.8%	33.0%	0.2%
KD1	86.9	60.4	25.5	1.0	69.5%	29.3%	1.2%
KD2	86.3	60.4	22.2	3.7	70.0%	25.7%	4.3%
KD3	84.9	60.4	24.4	0.1	71.1%	28.8%	0.1%
KD4	88.4	60.4	27.9	0.1	68.3%	31.6%	0.1%
KD5	89.1	60.4	28.5	0.2	67.8%	32.0%	0.2%
KD6	86.7	60.4	26.2	0.1	69.6%	30.2%	0.1%
KD7	85.8	60.4	25.3	0.1	70.4%	29.5%	0.1%
KD8	82.3	60.4	21.8	0.1	73.4%	26.5%	0.1%
KD9	75.9	60.4	15.5	0.1	79.5%	20.4%	0.1%
CKL1	80.5	60.4	20.0	0.1	75.0%	24.9%	0.1%
CKL2	78.1	60.4	17.6	0.1	77.3%	22.6%	0.1%
CKL3	75.3	60.4	14.8	0.1	80.2%	19.7%	0.1%
CKL4	82.7	60.4	21.9	0.4	73.1%	26.5%	0.5%
CKL5	75.9	60.4	15.5	0.1	79.5%	20.4%	0.1%
CKL6	80.5	60.4	19.6	0.5	75.1%	24.3%	0.6%

Table 4.21c Breakdown of Annual NO₂ Contributions (µg/m³ and Percentage)

ASR	Amount of Contribution of Annual Average NO₂ Concentration, µg/m³ (AQO = 80 µg/m³)				% of Contribution
ASR	Overall Cumulative	Back-ground	Other Sources	Trunk Road T2	Back-ground	Other Sources	Trunk Road T2
KB1	70.1	60.4	9.6	0.1	86.2%	13.7%	0.1%
KB2	71.5	60.4	11.1	0.1	84.5%	15.5%	0.1%
KB3	72.3	60.4	11.8	0.1	83.5%	16.3%	0.2%
KB4	72.6	60.4	12.1	0.1	83.2%	16.6%	0.1%
KB5	72.2	60.4	11.7	0.1	83.7%	16.2%	0.1%
KD1	73.9	60.4	12.9	0.6	81.7%	17.5%	0.8%
KD2	74.7	60.4	12.5	1.8	80.8%	16.8%	2.4%
KD3	70.6	60.4	10.2	0.0	85.5%	14.4%	0.1%
KD4	71.6	60.4	11.1	0.0	84.4%	15.5%	0.1%
KD5	71.3	60.4	10.9	0.0	84.7%	15.2%	0.1%
KD6	69.1	60.4	8.7	0.0	87.4%	12.6%	0.1%
KD7	69.0	60.4	8.6	0.0	87.5%	12.5%	0.1%
KD8	67.1	60.4	6.6	0.1	90.0%	9.9%	0.1%
KD9	65.7	60.4	5.3	0.0	91.9%	8.0%	0.1%
CKL1	66.8	60.4	6.2	0.2	90.4%	9.3%	0.3%
CKL2	66.0	60.4	5.6	0.1	91.5%	8.5%	0.1%
CKL3	65.8	60.4	5.4	0.1	91.7%	8.2%	0.1%
CKL4	71.7	60.4	11.2	0.1	84.2%	15.6%	0.2%
CKL5	64.5	60.4	3.3	0.8	93.6%	5.1%	1.3%
CKL6	64.5	60.4	4.1	0.0	93.6%	6.4%	0.1%

Table 4.22a Breakdown of 24-Hour RSP Contributions (µg/m³ and Percentage)

ASR	Amount of Contribution of 24-Hour Average RSP Concentration, µg/m³ (AQO = 180 µg/m³)				% of Contribution
ASR	Overall Cumulative	Back-ground	Other Sources	Trunk Road T2	Back-ground	Other Sources	Trunk Road T2
KB1	59.3	48.8	10.2	0.3	82.3%	17.3%	0.4%
KB2	60.5	48.8	11.3	0.5	80.6%	18.6%	0.8%
KB3	60.0	48.8	10.9	0.3	81.4%	18.1%	0.5%
KB4	61.5	48.8	12.6	0.0	79.4%	20.6%	<0.1%
KB5	60.0	48.8	11.2	0.0	81.3%	18.7%	<0.1%
KD1	59.2	48.8	9.5	0.9	82.4%	16.0%	1.6%
KD2	59.0	48.8	9.8	0.4	82.7%	16.6%	0.7%
KD3	60.1	48.8	11.3	0.0	81.1%	18.8%	<0.1%
KD4	61.6	48.8	12.8	0.0	79.2%	20.8%	<0.1%
KD5	60.0	48.8	11.2	0.0	81.4%	18.6%	<0.1%
KD6	61.3	48.8	12.5	0.0	79.6%	20.3%	<0.1%
KD7	61.2	48.8	12.4	0.0	79.7%	20.3%	<0.1%
KD8	58.6	48.8	9.8	0.0	83.3%	16.7%	<0.1%
KD9	56.2	48.8	7.4	0.0	86.8%	13.2%	<0.1%
CKL1	56.8	48.8	8.0	0.0	85.9%	14.1%	<0.1%
CKL2	56.4	48.8	7.6	0.0	86.5%	13.4%	<0.1%
CKL3	55.4	48.8	6.6	0.0	88.1%	11.9%	<0.1%
CKL4	56.8	48.8	8.0	0.0	85.9%	14.1%	<0.1%
CKL5	56.3	48.8	7.5	0.0	86.7%	13.3%	<0.1%
CKL6	56.8	48.8	7.9	0.1	85.9%	13.9%	0.2%

Table 4.22b Breakdown of Annual RSP Contributions (µg/m³ and Percentage)

ASR	Amount of Contribution of Annual Average RSP Concentration, µg/m³ (AQO = 55 µg/m³)				% of Contribution
ASR	Overall Cumulative	Back-ground	Other Sources	Trunk Road T2	Back- ground	Other Sources	Trunk Road T2
KB1	51.7	48.8	2.9	0.0	94.4%	5.6%	0.1%
KB2	52.2	48.8	3.3	0.1	93.5%	6.3%	0.2%
KB3	52.5	48.8	3.6	0.1	93.0%	6.8%	0.2%
KB4	52.6	48.8	3.8	0.0	92.7%	7.2%	0.1%
KB5	52.7	48.8	3.9	0.0	92.6%	7.4%	0.1%
KD1	53.0	48.8	3.4	0.8	92.0%	6.5%	1.5%
KD2	53.3	48.8	3.6	0.9	91.6%	6.8%	1.6%
KD3	52.6	48.8	3.8	0.0	92.8%	7.2%	<0.1%
KD4	53.2	48.8	4.3	0.0	91.8%	8.2%	<0.1%
KD5	53.3	48.8	4.5	0.0	91.6%	8.4%	<0.1%
KD6	52.5	48.8	3.6	0.0	93.0%	6.9%	<0.1%
KD7	52.6	48.8	3.8	0.0	92.8%	7.2%	<0.1%
KD8	51.3	48.8	2.5	0.0	95.0%	4.9%	0.1%
KD9	51.1	48.8	2.3	0.0	95.5%	4.4%	<0.1%
CKL1	50.9	48.8	2.1	0.0	95.8%	4.1%	0.1%
CKL2	50.7	48.8	1.9	0.0	96.3%	3.7%	<0.1%
CKL3	50.6	48.8	1.8	0.0	96.5%	3.5%	<0.1%
CKL4	52.4	48.8	3.6	0.0	93.1%	6.9%	0.1%
CKL5	50.2	48.8	1.2	0.2	97.3%	2.4%	0.3%
CKL6	50.2	48.8	1.4	0.0	97.2%	2.8%	<0.1%

4.10.3.6 As detailed in Tables 4.21a, b and c and Tables 4.22a and b above, the percentage contribution of the Trunk Road T2 ranges between only 0% to a maximum of 8.8% for NO_2,with the majority of the contributions being below 0.5%, and 0 - 1.5% for RSP. It can be seen that the background presents the highest contribution to the cumulative values.

4.10.3.7 The cumulative levels detailed in the Trunk Road T2 EIA report differ from those presented in the CKR and TKO-LTT EIA Reports even though all projects have included the same concurrent projects, including all the Route 6 projects as described in Section 1 and other background sources. This is as a result of the conservative approach adopted by the Trunk Road T2 EIA in determining the background levels of NO₂ and RSP. This Trunk Road T2 EIA has utilised the long term average (last five years) of the most recent air quality monitoring data obtained from the EPD’s Kwun Tong Air Quality Monitoring Station. This approach has been replaced by a modelling approach using the PATH (Pollutants in the Atmosphere and their Transport over Hong Kong) model in the CKR and TKO-LTT EIA reports. The background air quality estimated by PATH is less conservative than the above approach.

4.10.3.8 The background determined by the PATH approach for NO₂and used by the CKR EIA report is about 26 µg/m³while the background for the Trunk Road T2 is more than double at about 60 µg/m³. This results in the CKR EIA reporting cumulative annual NO₂ levels of 35-54 µg/m³,compared to the Trunk Road T2 values reported in Tables 4.20 and 4.21c above of between 65-72 µg/m³. A similar pattern is shown for the comparison of the 1–hour and 24-hour NO₂ and 24-hour and annual RSP levels between CKR EIA and the Trunk Road T2 EIA.

4.10.3.9 In terms of the TKO-LTT EIA, this pattern is, also, shown. The PATH background is about 20 µg/m³, again compared to the Trunk Road T2 value of about 60 µg/m³. This results in the TKO-LTT EIA reporting cumulative annual NO₂ levels of 39-40 µg/m³,compared to the Trunk Road T2 values reported in Tables 4.20 and 4.21c above of between 65-72 µg/m³.

4.10.4 Mitigation Measures

4.10.4.1 As detailed above, the operational air quality assessment has concluded that there will be no predicted exceedances of the relevant AQOs at all ASRs and no mitigation measures are recommended.

4.10.5 Residual Impacts

4.10.5.1 The residual impacts refer to the net impacts after mitigation, taking into account the background environmental conditions and the impacts from existing, committed and planned projects.

4.10.5.2 Residual air quality impacts associated with the operational phase of the Trunk Road T2 project have been assessed and as all pollutants comply with the AQOs at all designated ASRs and no significant and irreversible adverse residual impacts at these locations during the operational phase are predicted.

4.11 Environmental Monitoring and Audit

4.11.1.1 The assessment has concluded that mitigated construction dust impacts are within the acceptable levels and no adverse residual impacts will occur. However, it is recommended that, given the close proximity of the ASRs to the works site, that construction phase environmental monitoring and audit is undertaken to ensure that there are no adverse impacts during the implementation of the construction activities and ensure that recommended mitigation measures are implemented. EM&A during the operational phase is not required. Further details of the specific EM&A requirements are detailed in Section 12 of this report and in the EM&A Manual.

4.12 Summary and Conclusions

4.12.1.1 Potential air quality impacts from the construction works for the Trunk Road T2 construction works would mainly be related to construction dust from excavation, materials handling, spoil removal and wind erosion. With the implementation of hourly watering of all exposed areas and mitigation measures as defined in the Air Pollution Control (Construction Dust) Regulation, provision of dust enclosures at the conveyor belts, 3-sided barriers at the stockpiling areas and good site practices, adverse 1-hour, 24-hour or annual residual impacts would not occur. The predicted air impact would be unlikely to induce public health concern.

4.12.1.2 In respect of the operational phase of the Trunk Road T2, no exceedances of the NO₂or RSP AQOs are predicted and as such adverse operational phase residual impacts are not expected to occur.

^[1] http://www.epd.gov.hk/epd/english/environmentinhk/air/air_maincontent.html

^[2] http://www.epd.gov.hk/epd/english/environmentinhk/air/data/files/2010HKEIReportEng.pdf

^[3] http://www.epd.gov.hk/epd/english/environmentinhk/air/prob_solutions/cleaning_air_atroad.html

^[4] http://www.epd-asg.gov.hk/english/report/files/AQR2011e_final.pdf

^[5] http://www.epd.gov.hk/epd/english/environmentinhk/air/studyrpts/assessment_of_tap_measurements.html

^[6] http://www.epd.gov.hk/epd/english/news_events/legco/files/EA_Panel_110526a_eng.pdf

^[7] http://www.epd.gov.hk/epd/english/environmentinhk/air/prob_solutions/cleaning_air_atroad.html