Air pollution is possibly Hong Kong's most apparent and pressing environmental issue and one which has implications for the health of the population and the attractiveness of the SAR as a place in which to live and invest. The TAPs are of major concern because of their potential carcinogenic nature. The sustainability assessment process developed under the SUSDEV 21 study will include indicators relating to toxic air pollutants. In order to support application of these indicators and development of target values, baseline information of TAP must be collected.

The existing monitoring of TAPs by EPD can only provide ambient level concentrations, however, the most important sources of many of the TAPs of concern are vehicular exhaust emissions. A survey on roadside concentrations of these traffic-related TAPs is required to fill this information gap.

The results of this Study will supplement the data obtained from EPD for their TAPs monitoring. Within the Computer-Assisted Sustainability Evaluation Tool (CASET) developed by the SUSDEV 21 Study, this information can help to establish the existing baseline conditions, against which the sustainability implication of proposed strategic policies and projects can be assessed and evaluated.