TABLE OF CONTENT

3 Air Quality Impact. 3-1

3.1 Introduction. 3-1

3.2 Environmental Legislations, Standards and Guidelines. 3-1

3.3 Description of Environment 3-2

3.4 Identification of Air Sensitive Receivers. 3-3

3.5 Identification of Environmental Impacts. 3-7

3.6 Assessment Methodology. 3-9

3.7 Prediction and Evaluation of Environmental Impacts. 3-16

3.8 Mitigation of Adverse Environmental Impacts. 3-20

3.9 Evaluation of Residual Impacts. 3-22

3.10 Environmental Monitoring and Audit 3-22

3.11 Conclusion. 3-22

List of Drawings
Figure 3.1	Locations of Concerned PATH Grids
Figure 3.2	Locations of Representative Air Sensitive Receivers
Figure 3.3	Locations of Portals, Underpass Top Openings, Ventilation Building and Ventilation Exhausts
Figure 3.4	Locations of Marine Emission Sources
Figure 3.5	Original Austin Road Flyover Scenario and Revised Austin Road Flyover Scenario
Figure 3.6a	Contours of Cumulative 19^th Highest 1-hour NO2 Concentration (µg/m^3) at 1.5m Above Ground (Scenario 1)
Figure 3.6b	Contours of Cumulative 19^th Highest 1-hour NO2 Concentration (µg/m^3) at 1.5m Above Ground (Scenario 2)
Figure 3.6c	Contours of Cumulative 19^th Highest 1-hour NO2 Concentration (µg/m^3) at 1.5m Above Ground (Scenario 3)
Figure 3.6d	Contours of Cumulative 19^th Highest 1-hour NO2 Concentration (µg/m^3) at 15m Above Ground (Scenario 1)
Figure 3.6e	Contours of Cumulative 19^th Highest 1-hour NO2 Concentration (µg/m^3) at 15m Above Ground (Scenario 2)
Figure 3.6f	Contours of Cumulative 19^th Highest 1-hour NO2 Concentration (µg/m^3) at 15m Above Ground (Scenario 3)
Figure 3.6g	Contours of Cumulative 19^th Highest 1-hour NO2 Concentration (µg/m^3) at 20m Above Ground (Scenario 1)
Figure 3.6h	Contours of Cumulative 19^th Highest 1-hour NO2 Concentration (µg/m^3) at 20m Above Ground (Scenario 2)
Figure 3.6i	Contours of Cumulative 19^th Highest 1-hour NO2 Concentration (µg/m^3) at 20m Above Ground (Scenario 3)
Figure 3.7a	Contours of Cumulative Annual NO2 Concentration (µg/m^3) at 1.5m Above Ground (Scenario 1)
Figure 3.7b	Contours of Cumulative Annual NO2 Concentration (µg/m^3) at 1.5m Above Ground (Scenario 2)
Figure 3.7c	Contours of Cumulative Annual NO2 Concentration (µg/m^3) at 1.5m Above Ground (Scenario 3)
Figure 3.7d	Contours of Cumulative Annual NO2 Concentration (µg/m^3) at 15m Above Ground (Scenario 1)
Figure 3.7e	Contours of Cumulative Annual NO2 Concentration (µg/m^3) at 15m Above Ground (Scenario 2)
Figure 3.7f	Contours of Cumulative Annual NO2 Concentration (µg/m^3) at 15m Above Ground (Scenario 3)
Figure 3.7g	Contours of Cumulative Annual NO2 Concentration (µg/m^3) at 20m Above Ground (Scenario 1)
Figure 3.7h	Contours of Cumulative Annual NO2 Concentration (µg/m^3) at 20m Above Ground (Scenario 2)
Figure 3.7i	Contours of Cumulative Annual NO2 Concentration (µg/m^3) at 20m Above Ground (Scenario 3)
Figure 3.8a	Contours of Cumulative 10^th Highest Daily RSP Concentration (µg/m^3) at 1.5m Above Ground (Scenario 3)
Figure 3.8b	Contours of Cumulative 10^th Highest Daily RSP Concentration (µg/m^3) at 15m Above Ground (Scenario 3)
Figure 3.8c	Contours of Cumulative 10^th Highest Daily RSP Concentration (µg/m^3) at 20m Above Ground (Scenario 3)
Figure 3.9a	Contours of Cumulative Annual RSP Concentration (µg/m^3) at 1.5m Above Ground (Scenario 3)
Figure 3.9b	Contours of Cumulative Annual RSP Concentration (µg/m^3) at 15m Above Ground (Scenario 3)
Figure 3.9c	Contours of Cumulative Annual RSP Concentration (µg/m^3) at 20m Above Ground (Scenario 3)
Figure 3.10a	Contours of Cumulative 10th Highest Daily FSP Concentration (µg/m3) at 1.5m Above Ground (Scenario 3)
Figure 3.10b	Contours of Cumulative 10th Highest Daily FSP Concentration (µg/m3) at 15m Above Ground (Scenario 3)
Figure 3.10c	Contours of Cumulative 10th Highest Daily FSP Concentration (µg/m3) at 20m Above Ground (Scenario 3)
Figure 3.11a	Contours of Cumulative Annual FSP Concentration (µg/m^3) at 1.5m Above Ground (Scenario 3)
Figure 3.11b	Contours of Cumulative Annual FSP Concentration (µg/m^3) at 15m Above Ground (Scenario 3)
Figure 3.11c	Contours of Cumulative Annual FSP Concentration (µg/m^3) at 20m Above Ground (Scenario 3)

List of Appendices
Appendix 3.1	Traffic Forecast for Air Quality Assessment
Appendix 3.2	EMFAC-HK Model Assumptions
Appendix 3.3	Summary of Vehicular Emission Factors of 16 Vehicle Classes
Appendix 3.4	Summary of Composite Vehicular Emission Factors for CALINE4 Model
Appendix 3.5	Detailed Calculation of Emissions from Portals, Underpass Top Openings, Ventilation Building and Ventilation Exhausts
Appendix 3.6	Detailed Calculation of Emissions Associated with Bus, Minibus and Coach Terminuses
Appendix 3.7	Detailed Calculation of Marine Emission
Appendix 3.8	Detailed Emission Removal for PATH Re-run
Appendix 3.9	Determination of Surface Characteristics Parameters for AERMET
Appendix 3.10	Detailed Assessment Results
Appendix 3.11	Comparison between Revised Austin Road Flyover Scenario and Original Austin Road Flyover Scenario

List of Tables

Table 3.1 Hong Kong Air Quality Objectives. 3-1

Table 3.2 Average Concentrations of Pollutants in the Recent Five Years (Year 2015 ¡V 2019) at Sham Shui Po EPD Air Quality Monitoring Station. 3-2

Table 3.3 Background Air Pollutants Concentrations in Year 2020 Extracted from the PATH-2016 Model 3-3

Table 3.4 Representative Air Sensitive Receivers in the vicinity of the Project 3-3

Table 3.5 Tentative Transportation Routings. 3-7

Table 3.6 Predicted Worst-case Cumulative Concentrations at Representative Air Sensitive Receivers under Revised Austin Road Flyover Scenario. 3-16

Table 3.7 Comparison of Annual Average NO₂ Concentrations between 2 Scenarios at Selected ASRs and Assessment Levels with Exceedances of AQOs. 3-19

3 Air Quality Impact

3.1 Introduction

3.1.1.1 This section presents the assessment on potential air quality impacts arising from construction and operation of the Project, which has been conducted in accordance with the criteria and guidelines as stated in Section 1 of Annex 4 and Annex 12 of the Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM) as well as the requirements given in Clause 3.4.3 and Appendix B of the EIA Study Brief (No. ESB-316/2019).

3.2 Environmental Legislations, Standards and Guidelines

3.2.1.1 The criteria for evaluating air quality impacts and the guidelines for air quality assessment are laid out in Annex 4 and Annex 12 of the EIAO-TM.

3.2.2 Air Quality Objectives & Technical Memorandum on EIA Process

3.2.2.1 The Air Pollution Control Ordinance provides the statutory authority for controlling air pollutants from a variety of sources. The Hong Kong Air Quality Objectives (AQOs), which stipulate the maximum allowable concentrations over specific periods for typical pollutants, should be met. The prevailing AQOs are listed in Table 3.1.

Table 3.1 Hong Kong Air Quality Objectives

Pollutants	Averaging Time	Concentration Limit (µg/m^3)^[1]	Number of Exceedance Allowed per Year
Respirable Suspended Particulates (RSP or PM10) ^[2]	24-hour	100	9
	Annual ^[4]	50	N/A
Fine Suspended Particulates (FSP or PM2.5) ^[3]	24-hour	75	9
	Annual ^[4]	35	N/A
Nitrogen Dioxide (NO2)	1-hour	200	18
	Annual ^[4]	40	N/A
Sulphur Dioxide (SO2)	10-min	500	3
	24-hour	125	3
Carbon Monoxide (CO)	1-hour	30,000	0
	8-hour	10,000	0
Photochemical Oxidants (as ozone)	8-hour	160	9
Lead (Pb)	Annual ^[4]	0.5	NA

Note:

[1] Measured at 293K and 101.325kPa

[2] Suspended particulates in air with a nominal aerodynamic diameter of 10µm or smaller.

[3] Suspended particulates in air with a nominal aerodynamic diameter of 2.5µm or smaller.

[4] Arithmetic mean

3.2.2.2 The Annex 4 of EIAO-TM stipulated that hourly Total Suspended Particulates (TSP) level should not exceed 500 µg/m³ measured at 298K and 101.325kPa (one atmosphere) for construction dust impact assessment.

3.2.3 Air Pollution Control (Construction Dust) Regulation

3.2.3.1 Notifiable and regulatory works are under the control of Air Pollution Control (Construction Dust) Regulation. This Project is expected to include notifiable works (foundation and superstructure construction) and regulatory works (dusty material handling and excavation). Contractors and site agents are required to inform the Environmental Protection Department (EPD) and adopt dust reduction measures to minimize dust emission, while carrying out construction works, to the acceptable level.

3.2.4 Air Pollution Control (Non-road Mobile Machinery) (Emission) Regulation

3.2.4.1 The Air Pollution Control (Non-road Mobile Machinery) (Emission) Regulation comes into effect on 1 June 2015. Under the Regulation, Non-road mobile machinery (NRMMs), except those exempted, are required to comply with the prescribed emission standards. From 1 September 2015, all regulated machines sold or leased for use in Hong Kong must be approved or exempted with a proper label in a prescribed format issued by EPD. Starting from 1 December 2015, only approved or exempted NRMMs with a proper label are allowed to be used in specified activities and locations including construction sites. The Contractor is required to ensure the adopted machines or non-road vehicle under the Project could meet the prescribed emission standards and requirement.

3.3 Description of Environment

3.3.1.1 The Project site is situated within part of the WKCD area and across the toll plaza of the Western Harbour Crossing (WHC). The western boundaries of the Study Area are at the side of the WKCD Waterfront Promenade to the west of the WHC toll plaza, while the eastern boundaries of the Study Area are at the side of the Austin Road West / Nga Cheung Road roundabout. The surrounding land uses are mainly WKCD, comprehensive development area, other specified uses, government, institution or community (G/IC) uses and open space, as presented in Figure 2.1. The potential air pollution sources in the Study Area would be traffic emissions from the existing road networks, planned roads at WKCD, portal, top openings, ventilation building of Western Harbour Crossing (WHC), ventilation exhausts, bus, minibus and coach terminuses and marine emissions.

3.3.1.2 The nearest EPD general air quality monitoring station is Sham Shui Po monitoring station. The annual average monitoring data recorded at EPD¡¦s Sham Shui Po air quality monitoring station has shown steady trend of pollutants¡¦ concentration in the past five years. The recent five years (2015 ¡V 2019) annual average concentrations of air pollutants relevant to the Project are summarized in Table 3.2.

Table 3.2 Average Concentrations of Pollutants in the Recent Five Years (Year 2015 ¡V 2019) at Sham Shui Po EPD Air Quality Monitoring Station

Pollutant	Averaging Time		AQOs (µg/m^3)	2019	2018	2017	2016	2015
RSP	24-hr	10^th Highest	100	65	59	72	77	80
	Annual		50	33	33	33	35	38
FSP	24-hr	10^th Highest	75	36	41	46	48	58
	Annual		35	18	21	21	23	25
NO2	1-hr	19^th Highest	200	176	152	194	161	215
	Annual		40	48	49	54	58	63

Remarks:

[1] Monitoring results exceeded AQOs are shown as bold and underlined characters.

[2] Reference conditions of gaseous pollutants concentration data: 298K and 101.325 kPa.

3.3.1.3 Apart from the air quality monitoring data, EPD has released a set of background levels from ¡§Pollutants in the Atmosphere and their Transport over Hong Kong ¡V 2016¡¨ (PATH-2016) model. According to the PATH-2016 data (Year 2020) published by EPD, the concentrations of NO₂, RSP and FSP at various averaging times would be lower than the AQOs, except the annual average NO₂ concentrations. The air pollutant concentrations at the lowest level (i.e. level 1) for the concerned grids in the Study Area as illustrated in Figure 3.1, with reference to the PATH-2016 model in Year 2020, are summarized in Table 3.3.

Table 3.3 Background Air Pollutants Concentrations in Year 2020 Extracted from the PATH-2016 Model

Pollutant	Averaging Time		AQOs (µg/m^3)	Concentrations in PATH-2016 Grid in Year 2020(µg/m^3)^[1]
				(38,31)	(38,32)	(39,31)	(39,32)
RSP^[2]	24-hr	10^th Highest	100	87	85	83	81
	Annual		50	38	38	37	36
FSP ^[2] [3]	24-hr	10^th Highest	75	65	64	62	61
	Annual		35	27	27	26	25
NO2	1-hr	19^th Highest	200	182	175	189	155
	Annual		40	44	41	39	36

Remarks:

[1] Exceedance of the AQOs are shown as bold and underlined characters.

[2] 10^th highest daily and annual RSP concentration is adjusted by adding 26.5 µg/m³ and 15.6 µg/m³ respectively with reference to ¡§Guidelines on Choice of Models and Model Parameters¡¨. Same adjustment is applied to estimation of FSP as well.

[3] Since FSP is not available from PATH model outputs, 24-hour average FSP and annual average FSP are estimated by 0.75 x RSP and 0.71 x RSP respectively with reference to ¡§Guidelines on the Estimation of FSP for Air Quality Assessment in Hong Kong¡¨.

3.4 Identification of Air Sensitive Receivers

3.4.1.1 In accordance with Annex 12 of the EIAO-TM, any domestic premises, hotel, hostel, hospital, clinic, nursery, temporary housing accommodation, school, educational institution, office, factory, shop, shopping centre, place of public worship, library, court of law, sports stadium or performing arts centre are considered as air sensitive receivers (ASRs). Any other premises or place with which, in terms of duration or number of people affected, has a similar sensitivity to the air pollutants as the afforested premises and places is also considered to be a sensitive receiver.

3.4.1.2 In accordance with Clause 3.4.3.2 of the EIA Study Brief, the assessment area for air quality assessment should be defined by a distance of 500m from the boundary of the Project site. Illustration of the proposed assessment area is presented in Figure 3.1.

3.4.1.3 For identification of the representative ASRs within the assessment area that would likely be affected by the potential impacts from the construction and operation of the Project, a review has been conducted based on relevant available information including topographic maps, Outline Zoning Plans (OZPs) (such as OZP Plan No. S/K20/30 ¡V South West Kowloon) and other published plans in the vicinity of the Project site. The representative ASRs within the assessment area are identified and given in Table 3.4 below. Their locations are illustrated in Figure 3.2.

Table 3.4 Representative Air Sensitive Receivers in the vicinity of the Project

ASR ID	Description	Land Use ^[1]	Approximate Separation Distance from the Nearest Project Emission Sources (i.e. Road Alignment) (m)	Assessment Height Above Ground (mAG)	Note ^[2]	Consideration in Construction Phase [C] or Operation Phase [O]
Existing ASRs
CAS	Civil Aid Service Headquarters	G/IC	375	1.5 - 30	(A)	C&O
CUL1	The Cullinan I	R	95	50 - 280	(B)	C&O
CUL2	The Cullinan II	R&H	120	50 - 280	(B)	C&O
HT1	The HarbourSide ¡V Tower 1	R	255	30 - 240	(B)	C&O
HT2	The HarbourSide ¡V Tower 2	R	210	30 - 240	(B)	C&O
HT3	The HarbourSide ¡V Tower 3	R	170	30 - 240	(B)	C&O
ICC	International Commerce Centre	C	50	30 - 380	(C)	C&O
SRT	Sorrento ¡V Tower 1	R	130	30 - 280	(B)	C&O
TA1	Sky Tower, The Arch	R	320	30 - 180	(B)	C&O
TA2	Sun Tower, The Arch	R	365	30 - 180	(B)	C&O
TA3	Moon Tower, The Arch	R	395	30 - 180	(B)	C&O
TA4	Star Tower, The Arch	R	390	30 - 190	(B)	C&O
WHC	Western Harbour Crossing Administration Building	C	70	13	(D)	C&O
WT	Tower I, The Waterfront	R	305	15 - 150	(B)	C&O
P50G	Parcel 50	C	240	1.5 - 5	(E)	C&O
P50J	Parcel 50	C	245	1.5 - 5	(E)	C&O
P50K	Parcel 50	C	275	1.5 - 5	(E)	C&O
P51	Parcel 51	C	175	1.5 - 20	(E)	C&O
P52	Parcel 52	C	160	1.5 - 10	(E)	C&O
Planned ASRs under Construction
P35a	Parcel 35	C	175	1.5 - 40	(F)	C&O
P35b	Parcel 35	C	205	1.5 - 40	(F)	C&O
P35c	Parcel 35	C	300	1.5 - 40	(F)	C&O
P35d	Parcel 35	C	285	1.5 - 40	(F)	C&O
P39a	Parcel 39A	C	110	30 - 60	(F)	C&O
P39b	Parcel 39B	C	90	70 - 90	(F)	C&O
P40a	Parcel 40	C	190	15 - 90	(F)	C&O
P40b	Parcel 40	C	180	15 - 90	(F)	C&O
P40c	Parcel 40	C	160	15 - 90	(F)	C&O
P40d	Parcel 40	C	165	15 - 90	(F)	C&O
P40e	Parcel 40	C	285	15 - 90	(F)	C&O
P40f	Parcel 40	C	290	15 - 90	(F)	C&O
P40g	Parcel 40	C	275	15 - 90	(F)	C&O
P40h	Parcel 40	C	270	15 - 90	(F)	C&O
P46Aa	Parcel 46A - Hong Kong Palace Museum	C	90	20 - 50	(F)	C&O
P46Ab	Parcel 46A - Hong Kong Palace Museum	C	100	20 - 50	(F)	C&O
Planned ASRs with Detailed Design
FSC	TST Fire Station Complex	G/IC	250	1.5 - 60	(E)	O
Planned ASRs without Detailed Design
P16	Parcel 16	C	475	75	(G)	O
P17	Parcel 17	C	405	75	(G)	O
P18	Parcel 18	C	425	61	(G)	O
P19	Parcel 19	C	365	75	(G)	O
P22	Parcel 22	C	330	75	(G)	O
P23	Parcel 23	C	320	61	(G)	O
P24	Parcel 24	OU	295	10 - 91	(H)	O
P26	Parcel 26	C	290	75	(G)	O
P27	Parcel 27	OU	260	10 - 91	(H)	O
P28	Parcel 28	C	215	91	(G)	O
P29	Parcel 29	C	180	91	(G)	O
P30a	Parcel 30	C	225	61	(G)	O
P30b	Parcel 30	C	280	61	(G)	O
P30c	Parcel 30	C	360	61	(G)	O
P30d	Parcel 30	C	315	61	(G)	O
P31	Parcel 31	C	130	1.5 - 80	(I)	O
P32	Parcel 32	Hostel with Central Air-conditioning	215	1.5 - 40	(F)	O
P37	Parcel 37	C	60	1.5 - 70	(I)	O
P43a	Parcel 43	H	0	30 - 50	(J)	O
P43b	Parcel 43	H	0	30 - 50	(J)	O
P43c	Parcel 43	H	0	30 - 50	(J)	O
P43d	Parcel 43	H	0	30 - 50	(J)	O
P43e	Parcel 43	H	0	30 - 50	(J)	O
P43f	Parcel 43	H	0	30 - 50	(J)	O
P43g	Parcel 43	H	60	30 - 50	(J)	O
P43h	Parcel 43	H	100	30 - 50	(J)	O
P43i	Parcel 43	H	120	30 - 50	(J)	O
P43j	Parcel 43	H	130	30 - 50	(J)	O
P43k	Parcel 43	H	135	30 - 50	(J)	O
P43l	Parcel 43	H	140	30 - 50	(J)	O
P43m	Parcel 43	H	145	30 - 50	(J)	O
P43n	Parcel 43	H	155	30 - 50	(J)	O
P46a	Parcel 46 - Exhibition Centre	C	15	30 - 50	(J)	O
P46b	Parcel 46 - Exhibition Centre	C	15	30 - 50	(J)	O
P46c	Parcel 46 - Exhibition Centre	C	20	30 - 50	(J)	O

Remarks:

[1] ¡¥G/IC¡¦ stands for Government/Institution or Community; ¡¥R&H¡¦ stands for Residential and Hotel; ¡¥R¡¦ stands for Residential; ¡¥C¡¦ stands for Commercial; ¡¥OU¡¦ stands for Other Specified Uses; ¡¥H¡¦ stands for Hotel.

[2] Assumption of assessment heights:

(A) According to the information provided by Civil Aid Service, the fresh air intake of CAS is located from G/F to 7/F. Therefore, the assessment heights are taken as 1.5mAG, 5mAG, every 5m up to 20mAG and then 30mAG.

(B) The assessment heights start from the lowest residential floor and every 5m up to 20mAG, then every 10m up to 200mAG and every 20m up to the max. building height.

(C) The assessment heights of ICC are referenced to the approved Proposed Road Improvement Works in West Kowloon Reclamation Development ¡V Phase 1 ¡V Investigation, Design and Construction (PRIWWKRD) EIA Report (35 - 362mAG) [1]. Therefore, the assessment heights are taken as 30mAG, every 10m up to 200mAG and every 20m up to 380mAG.

(D) According to the as-built drawings, the fresh air intake of Western Harbour Crossing Administration Building is at 13mAG. Therefore, the assessment height is taken as 13mAG.

(E) The assessment heights are taken as 1.5mAG, 5mAG, every 5m up to 20mAG, then every 10m up to the max. building height.

(F) According to the latest design provided by WKCDA, the locations of fresh air intakes and the corresponding assessment heights for particular Parcels would be as below.

i. P32: 1.5mAG to 40mAG (1.5mAG, 5mAG, every 5m to 20mAG and then every 10m to 40mAG)

ii. P35: 1.5mAG to 40mAG (1.5mAG, 5mAG, every 5m to 20mAG and then every 10m to 40mAG)

iii. P39A: 30mAG to 60mAG (30mAG and then every 10m to 60mAG)

iv. P39B: 70mAG to 90mAG (70mAG, 80mAG and 90mAG)

v. P40: 15mAG to 90mAG (15mAG and every 5m to 20mAG and then every 10m to 90mAG)

vi. P46A: 20mAG to 50mAG (20mAG and then every 10m to 50mAG)

(G) According to the latest design provided by WKCDA, the fresh air intakes of commercial buildings in Zone 2 of WKCD would be located at the max. permissible building height for the below Parcels.

i. P16, P17, P19, P22 and P26: 75 mAG

ii. P18, P23 and P30a to P30d: 61 mAG

iii. P28 and P29: 91 mAG

(H) According to the latest design provided by WKCDA, the first air sensitive use levels of P24 and P27 would be 14mAG, with the max. building height below 80mAG and the highest fresh air intake at 91mAG. Therefore, the assessment heights are taken as 10mAG, 15mAG, 20mAG and every 10m up to 80mAG and then 91mAG.

(I) The assessment heights are referenced to the approved WKCD EIA Report [2].

(J) As advised by WKCDA, the locations of lowest fresh air intake and the corresponding assessment heights for particular Parcels would be designed as below.

i. P43: above 30mAG (30mAG and every 10m to 50mAG (max. assessment height in the approved WKCD EIA Report ²))

ii. P46: above 30mAG (30mAG and every 10m to 50mAG (max. permissible building height)). The existing WKCDA Project Site Office which is currently located in this area would be demolished when the Project starts operation. Therefore, the site office was not included in the assessment.

3.5 Identification of Environmental Impacts

3.5.1 Construction Phase

3.5.1.1 During the construction phase, the Project would generate fugitive dust with potential impacts on neighbouring ASRs from various construction activities, including site clearance (including demolition of existing carriageways), minor excavation with limited backfilling for column installation and wind erosion of limited exposed area. The bridge deck segments will be casted in a off-site fabrication yard and delivered to the Project site Potential dust impact from these other construction activities is not considered to be significant and no associated adverse dust impact is anticipated.

3.5.1.2 In addition, the abovementioned construction works would be of small scale and confined within small work area, work area with dusty activities (e.g. minor excavation with limited backfilling for column installation) would be less than 100 m² as confirmed by Project Engineer. The construction works of the Project would be divided into 2 Phases. Phase 1 construction would commence in Q2 2022 and to be completed in Q4 2024, while Phase 2 construction would commence in Q1 2023 and to be completed in Q4 2025, tentatively. During each phase of construction, construction activities would not take place at the entire construction work site at the same time, but to be undertaken at multiple work fronts at different construction periods. The construction activities at different work fronts would not take place concurrently. There would be around two dump trucks per day for loading and unloading with the tentative transporting routings presented in Table 3.5. The travel distance involved would be minimized and the use of highways would be maximized as much as possible to minimize the duration of transportation. In addition, the dump trucks would be covered by clean impervious sheeting to minimize dust nuisance to the nearby ASRs, Therefore, there would be no significant dust emission from the works area to the surrounding ASRs and adverse construction dust impact on the surrounding ASRs is not anticipated with implementation of mitigation measures stipulated in the Air Pollution Control (Construction Dust) Regulation.

Table 3.5 Tentative Transportation Routings

Destination	Tentative Transportation Routing
South East New Territories Landfill	Via Lin Cheung Road, West Kowloon Highway, Ching Cheung Road, Kwun Tong Road, TKO Tunnel Road, Wan Po Road
West New Territories Landfill	Via Lin Cheung Road, West Kowloon Highway, Tsing Kwai Highway, Tuen Mun Road, Lung Fu Road, Lung Mun Road, Nim Wan Road
Chai Wan Public Fill Barging Point	Via Lin Cheung Road, West Harbour Crossing tunnel and Central Wanchai Bypass, Island Eastern Corridor, Wing Tai Road
Tseung Kwan O Area 137 Fill Bank	Via Lin Cheung Road, West Kowloon Highway, Ching Cheung Road, Kwun Tong Road, TKO Tunnel Road, Wan Po Road
Chemical Waste Treatment Facility	Via Lin Cheung Road, West Kowloon Highway, Tsing Kwai Highway, Kwai Tsing Road, Tsing Yi Road

3.5.1.3 Fuel combustion from the use of powered mechanical equipment (PME) during construction works could be a source of NO₂, SO₂ and CO. Due to the small scale of work areas, limited amount of PME are required on site for the construction works. To improve air quality and protect public health, EPD has introduced the Air Pollution Control (Non-road Mobile Machinery) (Emission) Regulation, which came in operation on 1 June 2015, to regulate emissions from machines and non-road vehicles. Starting from 1 December 2015, only approved or exempted non-road mobile machinery are allowed to be used on construction sites and these approved or exempted non-road mobile machinery have emission limit values of air pollutants including particulate pollutants. Hence, with the implementation of the said Regulation, the emissions from PMEs are considered relatively small and would not cause adverse air quality impact to the surrounding ASRs.

3.5.2 Operation Phase

3.5.2.1 Potential air quality impacts during the operation phase of the Project would be associated with the following major pollution sources.

Emission Sources within 500m Study Area

¡P Background pollutant concentrations;

¡P Vehicular emissions from open sections of existing and proposed road networks within 500m away from the project site boundary (locations shown in Appendix 3.4);

¡P Portal emissions from the underpasses and landscape decks at Lin Cheung Road ¡V Austin Road West (locations shown in Figure 3.3);

¡P Top opening emissions from the underpasses at Lin Cheung Road ¡V Austin Road West (locations shown in Figure 3.3);

¡P Portal emissions from Western Harbour Crossing (locations shown in Figure 3.3);

¡P Ventilation building emissions from Western Harbour Crossing (locations shown in Figure 3.3);

¡P Ventilation exhaust emissions from underground roads within WKCD area (locations shown in Figure 3.3);

¡P Vehicular emissions associated with the bus terminus, minibus terminus and cross-boundary coach terminus at Kowloon Station and the bus terminus at West Kowloon Station (locations shown in Appendix 3.6);

¡P Marine emissions from China Ferry Terminal, New Yau Ma Tei Public Cargo Working Area (NYPCWA) and New Yau Ma Tei Typhoon Shelter (NYMTTS) (locations shown in Figure 3.4); and

Other Major Point Sources within 4km

¡P Marine emissions from Ocean Terminal (locations shown in Figure 3.4).

3.5.2.2 Based on the chimney survey conducted within the Study Area in Nov 2019, no active industrial chimney was identified.

Identification of Key Air Pollutants of Vehicular emissions

3.5.2.3 The Project induces vehicular emission from the open sections of the proposed road networks. Vehicular emission comprises a number of pollutants, including Nitrogen Oxides (NOx), Respirable Suspended Particulates (RSP), Fine Suspended Particulates (FSP), etc. According to ¡§An Overview on Air Quality and Air Pollution Control in Hong Kong¡¨ published in EPD¡¦s website, motor vehicles are the main causes of high concentrations of respirable suspended particulates (RSP) and nitrogen oxides (NOx) at street level in Hong Kong and are considered as key air quality pollutants for road projects. For other pollutants, due to the low concentration in vehicular emission, they are not considered as key pollutants for the purpose of this study.

(i) Nitrogen Dioxide (NO₂)

3.5.2.4 Nitrogen oxides (NOx) is a major pollutant from fossil fuel combustion. According to the 2017 Hong Kong Air Pollutant Emission Inventory Report published by EPD, navigation was the dominant contributor to NOx generation in Hong Kong, accounting for 37% of NOx emission in 2017. Road transport was also a major NOx contributor which accounted for 20% of the total in the same year.

3.5.2.5 In the presence of O₃ and VOC, NOx would be converted to NO₂. The operation of the proposed road networks would inevitably influence the distribution of NOx emission and subsequently the roadside NO₂ concentration. Hence, NO₂ is one of the key pollutants for the operational air quality assessment of the Project. 1-hour and annual average NO₂ concentrations at each identified ASRs would be assessed and compared with the relevant AQO to determine the compliance.

(ii) Respirable Suspended Particulates (RSP)

3.5.2.6 Respirable Suspended Particulates (RSP) refers to suspended particulates with a nominal aerodynamic diameter of 10µm or less. According to the 2017 Hong Kong Air Pollutant Emission Inventory Report published by EPD, navigation is the dominant contributor to RSP generation in Hong Kong, accounting for 34% of RSP emission in Year 2017. Road transport is also a RSP contributor which accounted for 10% of the total in the same year. The operation of the proposed road networks would inevitably influence the distribution of RSP emission and subsequently the roadside RSP concentration. Hence, RSP is also one of the key pollutants for the operational air quality assessment of the Project. 24-hour and annual average RSP concentrations at each identified ASRs would be assessed and compared with the relevant AQO to determine the compliance.

(iii) Fine Suspended Particulates (FSP)

3.5.2.7 Fine Suspended Particulates (FSP) refers to suspended particulates with a nominal aerodynamic diameter of 2.5µm or less. According to the 2017 Hong Kong Air Pollutant Emission Inventory Report published by EPD, navigation is the dominant contributor to RSP generation in Hong Kong, accounting for 41% of FSP emission in Year 2017. Road transport is also a FSP contributor which accounted for 12% of the total in the same year. The operation of the proposed road networks would inevitably influence the distribution of FSP emission and subsequently the roadside FSP concentration. Hence, FSP is also one of the key pollutants for the operational air quality assessment of the Project. 24-hour and annual average FSP concentrations at each identified ASRs would be assessed and compared with the relevant AQO to determine the compliance.

3.6 Assessment Methodology

3.6.1 Construction Phase

3.6.1.1 Considering the small scale and nature of the construction activities for the Project, and that construction activities at different work locations will not take place concurrently as well as adoption of precast concrete construction method will be adopted, there will be no significant dust emission from the works area to the surrounding ASRs and adverse construction dust impact to surrounding ASRs is not anticipated. Therefore, quantitative construction dust assessment was considered unnecessary.

3.6.2 Operation Phase

Vehicular Emissions from Open Roads

3.6.2.1 Open sections of existing and planned road networks within 500m Study Area of the Project were identified. The predicted 24-hour traffic flow and vehicle compositions at the identified roads during operation phase provided by the traffic consultant were adopted to assess the potential air quality impact from the open roads. The traffic data adopted for the assessment is presented in Appendix 3.1. Transport Department has no comment on the use of the traffic forecast for this Study and the endorsement letter is also attached in Appendix 3.1.

3.6.2.2 EMFAC-HK v4.2 model was adopted to estimate the vehicular emission rates of NO, NO₂ and RSP. The ¡§vehicle fleet¡¨ refers to all motor vehicles operating on roads within this assessment area. The modelled fleet is broken down into 16 vehicle classes based on the information in the Appendix 1 of Guideline on Modelling Vehicle Emissions published by EPD. The detailed input parameters and model assumptions made in EMFAC-HK model are summarized in Appendix 3.2.

3.6.2.3 The vehicular emission burdens of NOx and RSP from commencement year to 15 years after, namely Year 2025, 2031, 2035 and 2040, were estimated by using EMFAC-HK and are shown in Appendix 3.2. The vehicular emission attained the highest in Year 2025 and a decreasing trend was predicted in 15 years after project commencement. Year 2025 was therefore selected as the assessment year.

3.6.2.4 The NO, NO₂ and RSP running exhaust and start emission factors of 16 vehicle classes predicted by EMFAC-HK are presented in Appendix 3.3. The 24-hour traffic flows and composite emission factors for each road link adopted in the subsequent air dispersion modelling are presented in Appendix 3.4. All vehicular emissions of RSP were assumed for FSP as a conservative approach.

3.6.2.5 Secondary air quality impacts arising from the implementation of existing landscape deck and roadside noise mitigation measures, namely, vertical noise barriers, vertical noise barriers with canopies and semi-enclosure were incorporated into the air quality model. No direct noise remedies are proposed under the Project.

3.6.2.6 It is assumed that, with the installation of vertical noise barriers, all traffic pollutants generated from the mitigated road section are emitted from the top of the noise barriers. In the CALINE4 model, elevation of the mitigated road section was set to the elevation of the barrier top, and road type was set to ¡¥fill¡¦. No correction or adjustment to the receiver heights was made in the model.

3.6.2.7 For vertical noise barriers with canopies and semi-enclosure, it is assumed that dispersion of traffic pollutants is in effect similar to physically shifting the mitigated road section towards the central divider. The traffic pollutants are assumed to emit from the top of the canopies. In the CALINE4 model, the alignment of the mitigated road section was shifted by a distance equal to the covered extent, elevation of the mitigated road section was set to the elevation of the barrier top, and road type was set to ¡¥fill¡¦. No correction or adjustment to the receiver heights was made in the model.

Vehicular Emissions from Portals, Top Openings of the Underpasses and Landscape decks at Lin Cheung Road ¡V Austin Road West

3.6.2.8 The emissions from portals and top openings of the underpasses and landscape decks of Lin Cheung Road ¡V Austin Road West, (initial NO, initial NO₂ and RSP) were calculated based on the vehicular emission factors predicted by EMFAC-HK model and 24-hour vehicle flows provided by the traffic consultant. The locations and detailed calculations of the emissions are presented in Figure 3.3 and Appendix 3.5 respectively.

3.6.2.9 Calculations of emissions from the portals and top openings of the underpasses and landscape decks at Lin Cheung Road ¡V Austin Road West were made reference to the supporting document for the approved Variation of Environmental Permit (EP-453/2013/B) of WKCD EIA (WKCD VEP) [3], which adopted the worst scenario that 10% of tunnel emissions would be released through short top openings, while the remainder through the portal based on the conclusion drawn in the approved WKCD EIA Report ².

3.6.2.10 Portal emissions were modelled in accordance with the Permanent International Association of Road Congress Report [4]. Pollutants were assumed to eject from the portal as a portal jet such that 2/3 of the total emissions were dispersed within the first 50 m of the portal and 1/3 of the total emissions within the second 50 m.

Vehicular Emissions from Portals and Ventilation Building of WHC

3.6.2.11 The emissions from portals of WHC and ventilation building of WHC (initial NO, initial NO₂ and RSP) were calculated based on the vehicular emission factors predicted by EMFAC-HK model and 24-hour vehicle flows provided by the traffic consultant.

3.6.2.12 Due to the lack of information, three scenarios with different portions of emissions from the portals and the ventilation building were considered in the assessment. Similar approach was adopted in the approved PRIWWKRD EIA Report ¹.

¡P Scenario 1: 30% of emissions through portal and 70% through ventilation building

¡P Scenario 2: 50% of emissions through portal and 50% through ventilation building

¡P Scenario 3: 100% of emissions through portal and 0% through ventilation building

3.6.2.13 Portal emissions were modelled with the same approach as described in Section 3.6.2.10.

3.6.2.14 Design parameters of the ventilation building of WHC were referenced to the as-built information. The detailed calculation of emissions is presented in Appendix 3.5.

Vehicular Emissions from Ventilation Exhausts Serving Underground Roads within WKCD

3.6.2.15 The emissions from ventilation exhausts serving the underground roads within WKCD area (initial NO, initial NO₂ and RSP) were calculated based on the vehicular emission factors predicted by EMFAC-HK model and 24-hour vehicle flows provided by the traffic consultant. The underground road, namely Internal Road B, that the ventilation exhausts in Zone 2 of WKCD serve would be in operation in Year 2027 (i.e. 2 years after the commencement of the Project). As these ventilation exhausts are close to some representative ASRs, the vehicular emission induced by this underground road was taken into account to avoid any underestimation of air quality impacts. The emissions from these ventilation exhausts were calculated based on the traffic data of Year 2031 (the best available information which is expected to have a higher traffic flow than Year 2027) with vehicular emission factors in Year 2027 as predicted by EMFAC-HK as a conservative approach.

3.6.2.16 Calculations of emissions from the ventilation exhausts were made reference to the supporting document for the approved WKCD VEP ³, which adopted the worst scenario that 100% of the vehicular emissions from underground roads would be released through ventilation exhausts, and are presented in Appendix 3.5.

3.6.2.17 Design parameters of the ventilation exhausts were generally made reference to the Technical Note for Refinement of Ventilation Exhausts on Topside Development in Zone 2 [5] (for V25 ¡V V30), the supporting document for the approved WKCD VEP ³ (for V35 ¡V V38) and the latest information provided by WKCDA (for V31 ¡V V34).

Vehicular Emissions Associated with Bus, Minibus and Coach Terminuses

3.6.2.18 Despite the inclusion of start emissions on local and rural roads for most of the vehicle classes except franchised buses as detailed in Appendix 3.2, start emissions induced by the identified bus, minibus and coach terminuses were further simulated to avoid any underestimation of air quality impact at the exit of the terminuses. The start emissions, running exhaust emissions and idling emissions associated with the vehicles at the existing bus terminuses, minibus terminus and cross-boundary coach terminus at Kowloon Station and the bus terminus at West Kowloon Station within the assessment area (initial NO, initial NO₂ and RSP) were calculated based on the start emission and running exhaust emission factors predicted by EMFAC-HK model, cold idling emission factors from Calculation of Start Emissions in Air Quality Impact Assessment [6] published by EPD, warm idling emission factors from Road Tunnels: Vehicle Emissions and Air Demand for Ventilation published by World Road Association [7] and traffic data provided by the traffic consultant.

3.6.2.19 Calculations of emissions associated with the bus terminuses were made reference to the Calculation of Start Emissions in Air Quality Impact Assessment ⁶ (Appendix 3.6) published by EPD. Start emissions for diesel vehicles fitted with selective catalytic reduction (SCR) devices and LPG vehicles were adjusted based on the idling emission and would be released over a total spread distance of 700 m and 150 m respectively from where the start takes place, while running exhaust and idling emissions would be released on the spot. The locations of emission sources and the detailed calculation of the emissions are presented in Appendix 3.6.

Marine Emissions

3.6.2.20 China Ferry Terminal, NYMTTS, NYPCWA, Ocean Terminal and 2 planned piers at the WKCD are located in the vicinity of the Project. Emissions from the ferry services, tug movements, derrick lighter barges and cruises were considered in the assessment and the locations of the emission sources are shown in Figure 3.4.

3.6.2.21 China Ferry Terminal provides 8 berths for ferries to Macau and Pearl River Delta China (China). As reviewed from the arrival and departure schedules on TurboJet¡¦s website and the latest available online information on Marine Department¡¦s website (for the other 2 operators as no available information on their websites), the ferry services are provided from 07:00 to 22:00 daily. Emissions from the ferries during berthing and cruising in Victoria Harbour were calculated according to the number of ferries as reviewed from Marine Department¡¦s website, as confirmed with Marine Department.

3.6.2.22 The NYPCWA is located at the shoreline of NYMTTS. It mainly serves the purpose of loading and unloading cargos with the use of derrick lighter barges. The shoreline is approximately 1,250 metres long. With reference to the Merchant Shipping (Local Vessels) (Typhoon Shelters) Regulation ¡V Chapter 548E, the maximum permitted length for local vessels in NYMTTS is 50 metres. With the assumption of 5 metres at bow and stern for maneuvering purpose, the maximum number of vessels operating simultaneously is 20 (shoreline length divided by sum of vessel and maneuvering length). The NYPCWA is under operation from 07:00 to 21:00 daily.

3.6.2.23 With reference to the approved WKCD EIA, there are about 130 small craft movements both entering and leaving the NYMTTS per day, similar to the findings of site survey of a maximum of 9 numbers per hour conducted during this EIA study. All small crafts were assumed as tugs. The operation period was assumed the same as the NYPCWA, i.e. 07:00 to 21:00 daily. Emission from the tugs associated with the derrick lighter barge movements in the NYMTTS was included in the assessment.

3.6.2.24 There are 2 berths for cruises at Ocean Terminal. One of them is reserved for a 40,000-ton cruise, Star Pisces, which berths at Ocean Terminal from 08:00 to 19:30 from Monday to Friday and from 11:00 to 19:30 during weekends. Berthing time between 08:00 and 20:00 was assumed as a conservative approach. Another berth is for international cruises. According to the latest cruise schedule on Ocean Terminal¡¦s website, Queen Victoria is the largest cruise to the terminal with a length of 294m. Therefore, Queen Victoria, a 90,000-ton cruise, was considered representative among the visiting cruises and selected for the assessment as a reasonable and conservative assumption.

3.6.2.25 Two planned piers would be developed at the southern and northern sides of the WKCD for the potential marine traffic demand during WKCD¡¦s event periods and a new marine service within Victoria Harbour. According to the latest information provided by Transport Department, there would be a maximum of 4 regular in-harbour marine services daily from 11:00 to 21:00 using the southern pier. While there is no updated information for the northern pier at the time of study, the northern pier was not taken into account in the assessment. The latest location of the southern pier was advised by WKCDA and adopted in the assessment.

3.6.2.26 Detailed assumptions taken and calculation of marine emissions are presented in Appendix 3.7.

Background Contributions

3.6.2.27 As suggested by ¡§Guidelines on Assessing the ¡¥TOTAL¡¦ Air Quality Impacts¡¨, an integrated modelling system, Pollutants in the Atmosphere and their Transport over Hong Kong model (PATH-2016) which is developed and maintained by EPD was applied to estimate the background pollutant concentrations including those in Pearl River Delta Economic Zone, roads, marine, airport, power plants and industries within Hong Kong.

3.6.2.28 The Study Area covers 4 grid cells of PATH-2016, namely grid (38,31), (38,32), (39,31) and (39,32). The proposed works will be completed and will commence operation in Year 2025. As Year 2020 is the closest available year in PATH-2016 data currently, PATH-2016 data for Year 2020 of these 4 grid cells were adopted as the background concentration for the assessment. Level 1 (0mAG to 17mAG), level 2 (17mAG to 35mAG) and level 3 (35mAG or above) of PATH-2016 data were also adopted for cumulative impact assessment.

3.6.2.29 To avoid double counting, the vehicular emissions (from open roads, portals, top openings, ventilation building and ventilation exhausts) and marine emissions simulated with CALINE4 and AERMOD were removed from the emission inventory of PATH-2016 model. The detailed emission removal for PATH re-run is presented in Appendix 3.8.

Determination of the Assessment Scenarios

3.6.2.30 In order to calculate the incremental air quality impacts arising from the proposed road works, two Scenarios namely Original Austin Road Flyover Scenario and Revised Austin Road Flyover Scenario as described below have been assessed at the representative ASRs. The two Scenarios are illustrated in Figure 3.5.

¡P Original Austin Road Flyover Scenario ¡V Scenario with conforming road scheme presented in the approved WKCD EIA Report.

¡P Revised Austin Road Flyover Scenario ¡V Scenario with the proposed road works presented in Section 2 of this EIA report.

Dispersion Modelling & Modelling Approach

Vehicular emissions from Open Roads

3.6.2.31 CALINE4, the EPD approved line source air dispersion model developed by the California Department of Transport was used to assess the contribution due to vehicular emissions from the roads within 500m assessment area. The surface roughness coefficient of each grid in each assessment scenario is 370cm, which is the typical value for urban areas advised in ¡§Guidelines on Choice of Models and Model Parameters¡¨ by EPD.

3.6.2.32 Under the current EPD guideline, the hourly meteorological data including wind speed, wind direction, and air temperature from the relevant grids from the WRF Meteorological data (same basis for PATH-2016 model), were employed for the model run. PCRAMMET was applied to generate Pasquill-Gifford stability class for the meteorological input to CALINE4 model based on the WRF meteorological data.

Vehicular emissions from Portals, Top Openings, Ventilation Building, Ventilation Exhausts, Bus, Minibus and Coach Terminuses and Marine Emissions

3.6.2.33 AERMOD, the EPD approved air dispersion model, was employed to predict the air quality impact due to the vehicular emissions from the portals, top openings, ventilation building, ventilation exhausts, bus terminuses and marine emissions at the representative ASRs.

3.6.2.34 Vehicular and marine emission sources described in Section 3.5.2.1 were modelled as ¡§POINT¡¨, ¡§POINTHOR¡¨, ¡§AREA¡¨, ¡§AREAPOLY¡¨ and ¡§VOLUME¡¨ sources. The daily profiles adopted in AERMOD were based on the available information.

3.6.2.35 Hourly meteorological conditions including wind data, temperature, relative humidity, pressure cloud cover and mixing height of Year 2010 were extracted from the WRF meteorological data adopted in the PATH-2016 system. The minimum wind speed was capped at 1 metre per second. The mixing height was capped between 121 metres and 1667 metres according to the observation in Year 2010 by Hong Kong Observatory (HKO). The height of the input data was assumed to be 9 metres above ground for the first layer of the WRF data as input. In order to avoid any missing hours misidentified by AERMOD and its associated components, the WRF met data was handled manually to set wind direction between 0¢X ¡V 0.1¢X to be 360¢X. The meteorological data was input as on-site data into AERMET.

3.6.2.36 Surface characteristic parameters such as albedo, Bowen ratio and surface roughness are required in the AERMET (the meteorological pre-processor of AERMOD). The land use characteristics of the surrounding are classified and these parameters of each land use are then suggested by AERMET by default according to its land use characteristics. The detailed assumptions are discussed in Appendix 3.9. Flat terrain and urban mode in AERMOD were adopted for this assessment.

Ozone Limiting Method

3.6.2.37 For the cumulative assessment, Ozone Limiting Method (OLM) was adopted for conversion of NO from vehicle-related source (i.e. emissions from open roads, portals, top openings, ventilation building, ventilation exhausts and bus, minibus and coach terminuses) and NOx from marine sources to NO₂ based on the predicted O₃ level from PATH-2016. According to the Heathrow Airport EIA Report [8], the initial NO₂/NOx ratios of marine emission sources are 10%. The predicted initial NO concentrations from open roads (from CALINE4), portals, top openings, ventilation building, ventilation exhausts and bus, minibus and coach terminuses (from AERMOD) and 90% of the NOx concentrations from marine emissions (from AERMOD) were firstly added together on an hour-to-hour basis and OLM was applied subsequently. The NO₂/NOx conversion was calculated as follows:

[NO₂]_predicted = [NO₂]_vehicular + 0.1 ´ [NO_X]_marine + MIN {[NO]_vehicular + 0.9 ´ [NO_X]_marine, or (46/48) ´ [O₃]_PATH}

where

[NO₂]_predicted is the predicted NO₂ concentration

[NO₂]_vehicular is the sum of predicted initial NO₂ concentration from open roads, portals, top openings, ventilation building, ventilation exhausts and bus, minibus and coach terminuses

[NO]_vehicular is the sum of predicted initial NO concentration from open roads, portals, top openings, ventilation building, ventilation exhausts and bus, minibus and coach terminuses

[NOx]_marine is the sum of predicted NOx concentration from marine emissions

MIN means the minimum of the two values within the brackets

[O₃]_PATH is the representative O₃ PATH concentration (from other contribution)

(46/48) is the molecular weight of NO₂ divided by the molecular weight of O₃

Cumulative Air Quality Impact

3.6.2.38 The PATH-2016 model output was added to the sum of the CALINE4 and AERMOD model results sequentially on an hour-to-hour basis to derive the short-term and long-term cumulative impacts at the ASRs for the three emission scenarios of the portals and the ventilation building of WHC separately under both Original Austin Road Flyover Scenario and Revised Austin Road Flyover Scenario. The highest predicted concentration among the three scenarios of the portals and the ventilation building of WHC at each representative ASR was then selected and presented in Section 3.7.2.

3.6.2.39 With reference to the EPD¡¦s Guidelines on Choice of Models and Model Parameters, PATH-2016¡¦s output of RSP concentrations are adjusted as follows:

¡P 10^th highest daily RSP concentration: add 26.5 µg/m³

¡P Annual RSP concentration: add 15.6 µg/m³

3.6.2.40 With reference to the EPD¡¦s Guidelines on the Estimation of PM_2.5 for Air Quality Assessment in Hong Kong, the following conservative formulae were adopted to calculate background FSP concentration from the RSP concentration extracted from PATH-2016 model:

¡P Annual (µg/m³): PM_2.5 = 0.71 ¡Ñ PM₁₀

¡P Daily (µg/m³): PM_2.5 = 0.75 ¡Ñ PM₁₀

3.6.3 Level of Uncertainty in the Assessment

3.6.3.1 There would be some limitations such as the accuracy of the predictive base data for future conditions e.g. traffic flow forecasts. Uncertainties in the assessment of impacts have been considered when drawing conclusions from the assessment.

3.6.3.2 In carrying out the assessment, realistic worst-case assumptions have been made in order to provide a conservative assessment of air quality impacts. The air quality impact was assessed based on conservative estimates for the emission distribution from portals, openings and ventilation building as well as the operation pattern and emission from marine vessels.

3.7 Prediction and Evaluation of Environmental Impacts

3.7.1 Construction Phase

3.7.1.1 As mentioned in Section 3.5.1.1 to Section 3.5.1.3, the Project would not generate significant dust emission during the construction works due to the small scale and nature of the construction works, and construction activities would not be conducted concurrently at different work locations as well as adoption of precast concrete construction method for bridge construction. Hence, there would be no significant dust emission from the works area to the surrounding ASRs and adverse construction dust impact to surrounding ASRs is not anticipated. Nevertheless, dust suppression measures are recommended in Section 3.8.1 and implementation of mitigation measures stipulated in the Air Pollution Control (Construction Dust) Regulation to minimize the potential dust emission from the construction of the Project.

3.7.1.2 As mentioned in Section 3.5.1.3, the emissions from PMEs are considered relatively small. Hence, adverse air quality impact arising from the use of PME to the surrounding ASRs is not anticipated.

3.7.1.3 The construction period of the Project potentially overlaps with nearby concurrent projects as identified in Section 2.12. The dusty construction activities such as excavation and foundation works of Integrated Basement for West Kowloon Cultural District ¡V Zone 3B and Artist Square Bridge of West Kowloon Cultural District projects would be likely to be completed by Q2 Year 2022 and therefore would unlikely overlap with the dusty construction activities of the Project, while the dusty construction activities of Exhibition Centre in Zone 4 of West Kowloon Cultural District would be completed by Q4 Year 2022 before the commencement of Phase 2 construction works of the Project. In addition, work sites of Integrated Basement for West Kowloon Cultural District ¡V Zone 2BC project are located around 200m away from the Project and are situated at a different direction from the view of the representative ASRs. As there was no detailed information available for Piers in the WKCD at the time of assessment, it was not included in the assessment. With further incorporation of the mitigation measures as mentioned in Section 3.8.1 during the construction phase of the Project, cumulative construction dust impact is not expected.

3.7.2 Operation Phase

3.7.2.1 The cumulative air quality impacts due to background pollutant concentrations, and emissions from open roads, portals, top openings, ventilation building, ventilation exhausts, bus, minibus and coach terminuses and marine traffic within 500m assessment area at the representative ASRs have been evaluated. The predicted worst-case cumulative air quality impacts at the ASRs are summarized in Table 3.6. The detailed assessment results for the three scenarios of WHC portals and ventilation building are presented in Appendix 3.10.

Table 3.6 Predicted Worst-case Cumulative Concentrations at Representative Air Sensitive Receivers under Revised Austin Road Flyover Scenario

ASR	NO2 Concentration (µg/m^3)		RSP Concentration (µg/m^3)		FSP Concentration (µg/m^3)
	19^th Highest Hourly Average	Annual Average	10^th Highest Daily Average	Annual Average	10^th Highest Daily Average	Annual Average
AQO	200	40	100	50	75	35
CAS	151 - 167	32 - 44	81 - 82	36	61	26
CUL1	134 - 139	25 - 28	81	36	61	25 - 26
CUL2	134 - 142	26 - 28	81	36	61	25 - 26
FSC	138 - 168	27 - 45	81 - 82	36	61	25 - 26
HT1	150 - 170	28 - 34	83	37	62 - 63	26
HT2	150 - 169	28 - 35	83	37	62 - 63	26
HT3	150 - 169	28 - 35	83	37	62 - 63	26
ICC	150 - 170	28 - 35	83	37	62 - 63	26
SRT	134 - 153	25 - 33	81	36	61	25 - 26
TA1	150 - 172	28 - 34	83	37	62 - 63	26
TA2	150 - 172	28 - 34	83	37	62 - 63	26
TA3	150 - 172	28 - 34	83	37	62 - 63	26
TA4	150 - 170	28 - 34	83	37	62 - 63	26
WT	135 - 166	26 - 39	81	36	61	25 - 26
WHC	186	47	84	37	63	27
P16	164	30	83	37	63	26
P17	162	30	83	37	63	26
P18	155	31	83	37	63	26
P19	161	30	83	37	63	26
P22	155	30	83	37	63	26
P23	155	31	83	37	63	26
P24	152 - 189	30 - 42	83 - 84	37	62 - 63	26
P26	155	31	83	37	63	26
P27	152 - 189	30 - 43	83 - 84	37	62 - 63	26
P28	154	30	83	37	62	26
P29	152	30	83	37	62	26
P30a	153	31	83	37	63	26
P30b	155	31	83	37	63	26
P30c	155	31	83	37	63	26
P30d	155	32	83	37	63	26
P31	153 - 195	30 - 49	83 - 84	37	62 - 63	26 - 27
P32	154 - 190	32 - 44	83 - 84	37	63	26 - 27
P35a	154 - 192	32 - 46	83 - 84	37	63	26 - 27
P35b	154 - 191	32 - 44	83 - 84	37	63	26 - 27
P35c	154 - 184	33 - 45	83 - 84	37	63	26 - 27
P35d	155 - 183	33 - 44	83 - 84	37	63	26 - 27
P37	154 - 197	30 - 53	83 - 84	37 - 38	62 - 63	26 - 27
P39a	153 - 166	31 - 36	83	37	63	26
P39b	152 - 153	30 - 31	83	37	62	26
P40a	158 - 199	32 - 45	87	38	65 - 66	27
P40b	151 - 195	31 - 44	83 - 84	37	62 - 63	26 - 27
P40c	152 - 192	31 - 42	83 - 84	37	62 - 63	26
P40d	152 - 192	31 - 42	83 - 84	37	63	26
P40e	153 - 181	32 - 42	83 - 84	37	63	26 - 27
P40f	153 - 181	32 - 42	83 - 84	37	63	26 - 27
P40g	152 - 182	32 - 43	83 - 84	37	63	26 - 27
P40h	152 - 182	32 - 43	83 - 84	37	63	26 - 27
P43a	157 - 164	33 - 38	87	38	65	27
P43b	157 - 164	33 - 38	87	38	65	27
P43c	157 - 164	33 - 38	87	38	65	27
P43d	157 - 164	33 - 38	87	38	65	27
P43e	157 - 164	33 - 38	87	38	65	27
P43f	157 - 164	33 - 38	87	38	65	27
P43g	159 - 166	34 - 38	87	38	65	27
P43h	158 - 165	35 - 39	87	38	65	27
P43i	160 - 169	33 - 38	87	38	65	27
P43j	157 - 169	33 - 38	87	38	65	27
P43k	157 - 169	33 - 38	87	38	65	27
P43l	161 - 169	34 - 38	87	38	65	27
P43m	161 - 170	33 - 38	87	38	65	27
P43n	160 - 171	33 - 38	87	38	65	27
P46a	157 - 165	33 - 38	87	38	65	27
P46b	157 - 165	33 - 38	87	38	65	27
P46c	157 - 165	33 - 38	87	38	65	27
P46Aa	157 - 168	34 - 46	87	38	65 - 66	27
P46Ab	159 - 168	35 - 44	87	38	65 - 66	27
P50G	193	48	88	38	66	27
P50J	193 - 194	50	88	38	66	27
P50K	190 - 191	50 - 51	88	38 - 39	66	27 - 28
P51	169 - 193	41 - 52	87 - 88	38 - 39	66	27 - 28
P52	192 - 193	48 - 51	88 - 89	38 - 39	66 - 67	27 - 28

Remarks:

[1] Exceedance of the AQOs are shown as bold and underlined characters.

3.7.2.2 According to the predicted results in Table 3.6, the predictions indicated that the 19^th highest hourly average NO₂, 10^th highest daily average and annual average of RSP and FSP concentrations at all representative ASRs would comply with the respective AQOs, while the predicted annual average NO₂ concentrations at some ASRs under Revised Austin Road Flyover Scenario show exceedances against AQOs.

3.7.2.3 According to the predicted results, the worst hit level at the representative ASRs generally appears at the first air sensitive use level. 1.5mAG, 15mAG and 20mAG were considered the best representing the lowest level of most of the air sensitive uses within the Study Area. From the discrete cumulative results, Scenario 3 (100% of WHC emissions released through portal) was the worst scenario at most of the low-level receivers. The predicted concentrations at the representative ASRs under the worst scenario and Scenario 3 were further compared. The max. difference in 10^th highest daily average RSP and FSP concentrations is 0.01 µg/m³, and the max. difference in annual average RSP and FSP concentrations is 0.03 µg/m³, which appear at high-level receivers (above 40mAG). In addition, ASRs near the WHC ventilation building (WHCVB) (e.g. P50K and P51) attained the highest predicted concentrations under Scenario 3 as their building heights are only up to 20mAG while the exhaust of WHCVB is located at 28mAG. Given the large margin to AQOs (where the max. 10^th highest daily average RSP and annual average RSP concentrations are 89 µg/m³ and 39 µg/m³ respectively, while the max. 10^th highest daily average FSP and annual average FSP concentrations are 67 µg/m³ and 28 µg/m³, respectively), no additional exceedance zone would be anticipated arising from the emissions from WHCVB in this area under the other two scenarios (Scenario 1 and Scenario 2). Therefore, contour plots for the pollutants RSP and FSP prepared with the cumulative concentrations under Scenario 3 are considered sufficient and representative. While NO₂ concentrations show more significant variations towards different scenarios, contour plots for the pollutant NO₂ were prepared with the cumulative concentrations under the three Scenarios respectively to reflect all possible situations. Contour plots of the 19^th highest hourly average and annual average NO₂ concentrations, 10^th highest daily average and annual average RSP concentrations, and 10^th highest daily average and annual average FSP concentrations at these worst affected levels under Revised Austin Road Flyover Scenario are thus predicted and presented in Figure 3.6 to Figure 3.11.

3.7.2.4 Referring to Figure 3.6a to Figure 3.6c and Figure 3.6f, exceedance zones are found for the 19^th highest hourly average NO₂ concentration at 1.5mAG and 15mAG. However, no air sensitive uses are identified within these areas. Figure 3.8 to Figure 3.11 indicate there are no exceedances in 10^th daily average and annual average of RSP and FSP concentrations at all levels. Exceedance zones are found for the annual average NO₂ concentrations at 1.5mAG, 15mAG and 20mAG in Figure 3.7a to Figure 3.7i.

3.7.2.5 In order to investigate whether the Project would induce any adverse impact, changes in annual average NO₂ concentrations between two Scenarios for the ASRs with exceedance of AQOs are presented in Table 3.7. Detailed concentration changes in NO₂, RSP and FSP between Revised Austin Road Flyover Scenario and Original Austin Road Flyover Scenario are presented in Appendix 3.11.

Table 3.7 Comparison of Annual Average NO₂ Concentrations between 2 Scenarios at Selected ASRs and Assessment Levels with Exceedances of AQOs

ASR	Annual Average NO2 Concentration (µg/m^3)
	Revised Austin Road Flyover Scenario	Original Austin Road Flyover Scenario	Concentration Change (Revised Austin Road Flyover Scenario ¡V Original Austin Road Flyover Scenario)
CAS	42 - 44	42 - 44	-0.03119 - -0.03041
FSC	41 - 45	41 - 45	-0.07115 - -0.0683
WHC	47	47	-0.29834
P24	41 - 42	41 - 42	-0.04005 - -0.03982
P27	41 - 43	41 - 43	-0.04493 - -0.04472
P31	42 - 49	42 - 49	-0.08065 - -0.07732
P32	41 - 44	41 - 44	-0.05843 - -0.05481
P35a	42 - 46	42 - 46	-0.08574 - -0.07349
P35b	41 - 44	41 - 44	-0.06066 - -0.05685
P35c	41 - 45	41 - 45	-0.04591 - -0.04376
P35d	42 - 44	42 - 44	-0.05727 - -0.05274
P37	44 - 53	44 - 53	-0.26339 - -0.1053
P40a	45	45	-0.09176
P40b	44	44	-0.10813
P40c	42	42	-0.08189
P40d	42	42	-0.07993
P40e	42	42	-0.05344
P40f	42	42	-0.05448
P40g	43	43	-0.06892
P40h	43	43	-0.07072
P46Aa	41 - 46	41 - 46	-0.19258 - -0.08506
P46Ab	44	44	-0.17153
P50G	48	48	-0.06375 - -0.06304
P50J	50	50	-0.06302 - -0.06267
P50K	50 - 51	50 - 51	-0.0665 - -0.06586
P51	41 - 52	41 - 52	-0.09584 - -0.0715
P52	48 - 51	48 - 51	-0.11242 - -0.09473

Remarks:

[1] Exceedance of the AQOs are shown as bold and underlined characters.

3.7.2.6 With the Project, the Kowloon Station topside development traffic from the elevated Nga Cheung Road would be diverted away from ASRs to the Revised Austin Road Flyover, and therefore the ¡§Revised Austin Road Flyover¡¨ would improve annual average NO₂ concentrations at the identified ASRs. According to Table 3.7, there would be a decrease in annual average NO₂ concentration compared to the ¡§Original Austin Road Flyover¡¨ Scenario, stated in the approved WKCD EIA Report ², which indicated the Project would bring improvements in terms of air quality aspect and no adverse impact would be generated due to the Project during the operation phase.

3.8 Mitigation of Adverse Environmental Impacts

3.8.1 Construction Phase

3.8.1.1 Although no adverse dust impact is anticipated from the Project to the surrounding ASRs, the approved NRMMs under NRMM Regulation (excluding exempted NRMMs) would be used on site and NRMMs supplied with mains electricity instead of diesel-powered should be adopted as far as possible to minimize the potential emission from NRMMs.

3.8.1.2 In addition, dust suppression measures in the Air Pollution Control (Construction Dust) Regulation and good site practices should be incorporated to control dust emission from the site. Major control measures relevant to this Project are listed below, and they are recommended to be included in relevant contract documents:

¡P Skip hoist for material transport should be totally enclosed by impervious sheeting.

¡P All dusty materials should be sprayed with water prior to any loading, unloading or transfer operation so as to maintain the dusty materials wet.

¡P All stockpiles of aggregate or spoil should be covered and/or water applied.

¡P The height from which excavated materials are dropped should be controlled to a minimum practical height to limit fugitive dust generation from unloading.

¡P Every vehicle should be washed to remove any dusty materials from its body and wheels before leaving the construction sites.

¡P The load of dusty materials carried by a vehicle leaving a construction site should be covered entirely by clean impervious sheeting to ensure dust materials do not leak from the vehicle

¡P Erection of hoarding of not less than 2.4m high from ground level along the site boundary which adjoins a road, street, service lane or other area accessible to the public

3.8.1.3 With the implementation of the mitigation measures, unacceptable construction dust impact would not be anticipated.

3.8.2 Operation Phase

3.8.2.1 With the Project, the Kowloon Station topside development traffic from the elevated Nga Cheung Road would be diverted away from ASRs to the Revised Austin Road Flyover, and therefore the ¡§Revised Austin Road Flyover¡¨ would improve annual average NO₂ concentrations at the identified ASRs. According to Table 3.7, there would be a decrease in annual average NO₂ concentration compared to the ¡§Original Austin Road Flyover¡¨ Scenario which indicated the Project would bring improvements in terms of air quality aspect and no adverse impact would be generated due to the Project during the operation phase. The exceedances of annual average NO₂ concentrations predicted at some existing and planned representative ASRs, as presented in Appendix 3.10, are mainly resulted from the relatively high concentration of background air pollution in this area. In addition, the predicted 19^th highest hourly average NO₂, 10^th daily average and annual average RSP and FSP concentrations at all representative ASRs would comply with the respective AQOs.

3.8.2.2 Although unacceptable air quality impact is not anticipated due to the Project during the operation phase, some mitigation measures such as relocation of fresh air intakes at elevated levels with AQO compliance and provision of air purification filters have been considered due to the high background level of NO₂. For the existing ASRs, planned ASRs under construction and planned ASRs with detailed design, these mitigation measures were considered not feasible in time as the designs have already been completed or in some cases even physical buildings have been completed. For the planned ASRs without detailed design, the future WKCD project owner(s) within the Study Area would be notified of the findings under this air quality impact assessment in EIA of Revised Austin Road Flyover for consideration so that the relevant mitigation measures could be implemented as far as practicable.

Enhancement Measures

3.8.2.3 With a view to further improve the air quality condition in the concerned area, the following enhancement measures would also be taken forward.

Reduction of Emissions at Source

3.8.2.4 Electric vehicles will be proposed for the feeder services and shuttle bus travelling inside WKCD between Xiqu Centre and Hong Kong Palace Museum which has the potential to reduce the vehicular tailpipe emissions at WKCD. For the vehicular emissions from the ventilation exhausts in Zone 2 related to the Underground Road, an air purification system for NOx removal will be installed at the ventilation exhausts of the Underground Road to minimize the air quality impact on the representative ASRs.

Use of NOx Reduction Measure

3.8.2.5 Apart from reduction of emissions at source, use of NOx reduction measure in form of de-NOx painting on the parapet and/or the use of NOx reducing paver to the reinstated footpath in WKCD would be an enhancement measure to further improve the surrounding air quality impact and would be further investigated in the future detailed design.

3.9 Evaluation of Residual Impacts

3.9.1 Construction Phase

3.9.1.1 With the implementation of the mitigation measures as stipulated in the Air Pollution Control (Construction Dust) Regulation together with the recommended dust suppression measures and good site practices on the work sites as described in Section 3.8.1, no adverse residual impact would be expected during the construction phase of the Project.

3.9.2 Operation Phase

3.9.2.1 No adverse residual air quality impact due to the Project is anticipated during the operation phase of the Project.

3.10 Environmental Monitoring and Audit

3.10.1 Construction Phase

3.10.1.1 EM&A for potential dust impacts should be conducted during construction phase so as to check compliance with the legislative requirements. Details of the monitoring and audit programme are contained in a stand-alone EM&A Manual.

3.10.1.2 Weekly site audits for potential dust impact are recommended to be conducted during the entire construction phase of the Project so as to ensure the dust mitigation measures and the dust suppression measures stipulated in Air Pollution Control (Construction Dust) Regulation are implemented in order.

3.10.2 Operation Phase

3.10.2.1 No adverse impact would be generated due to the Project during the operation phase of this Project. Therefore, the environmental monitoring and audit (EM&A) works for the operational phase is considered unnecessary.

3.11 Conclusion

3.11.1 Construction Phase

3.11.1.1 Potential dust impact generated from construction activities, such as site clearance, minor excavation with limited backfilling for column installation, superstructure works, wind erosion of exposed area, and emission from PMEs would not be significant. With the implementation of mitigation measures specified in the Air Pollution Control (Construction Dust) Regulation together with the recommended dust suppression measures and good site practices, no adverse dust impact at ASRs is anticipated due to the construction activities of the Project.

3.11.2 Operation Phase

3.11.2.1 The ¡§Revised Austin Road Flyover¡¨ would improve annual average NO₂ concentrations at the identified ASRs. There would be a decrease in annual average NO₂ concentration compared to the ¡§Original Austin Road Flyover¡¨ Scenario which indicated the Project would bring improvements in terms of air quality aspect and no adverse impact would be generated due to the Project during the operation phase. The exceedances of annual average NO₂ concentrations predicted at some existing and planned representative ASRs are mainly resulted from the relatively high concentration of background air pollution in this area. In addition, the predicted 19^th highest hourly average NO₂, 10^th daily average and annual average RSP and FSP concentrations at all representative ASRs would comply with the respective AQOs.

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[1] Highways Department. 2013. Proposed Road Improvement Works in West Kowloon Reclamation Development ¡V Phase 1 ¡V Investigation, Design and Construction Environmental Impact Assessment Report (AEIAR-179/2013). Prepared by Parsons Brinckerhoff (Asia) Ltd.

[2] West Kowloon Cultural District Authority. 2013. West Kowloon Cultural District Environmental Impact Assessment Report (AEIAR- 178/2013). Prepared by Mott MacDonald.

[3] West Kowloon Cultural District Authority. 2016. Supporting document for the Variation of Environmental Permit (EP-453/2013/B). Prepared by Mott MacDonald.

[4] World Road Association. 1991. XIXth World Road Congress Report, Permanent International Association of Road Congresses.

[5] West Kowloon Cultural District Authority. 2019. Technical Note for Refinement of Ventilation Exhausts on Topside Development in Zone 2. Prepared by AECOM Asia Co. Ltd.

[6] Environmental Protection Department. 2020. Calculation of Start Emissions in Air Quality Impact Assessment.

[7] World Road Association. 2019. Road Tunnels: Vehicle Emissions and Air Demand for Ventilation.

[8] Department for Transport. 2007. Air Quality Studies for Heathrow: Base Case, Segregated Mode, Mixed Mode and Third Runway Scenarios modelled using ADMS-Airport. Prepared by Cambridge Environmental Research Consultants.