THE ENVIRONMENT
Short-term air quality studies were carried out to tie in with the implementation of the Air Pollution Control (Fuel Restriction) Regulations in July. Significant improvement in air quality was confirmed by measurements at a residential block in Kwai Chung which was once much affected by industrial emissions. For the first 10 days after imple- mentation, reductions in particulate levels and nitrogen dioxide ranged from about 15 to 30 per cent, and the reduction in sulphur dioxide levels was as much as 80 per cent. The ambient sulphur dioxide concentrations measured at other monitoring stations were also lower. When compared with the monitoring results for the same periods in the past three years, the reduction in sulphur dioxide concentration for the six-month period since July 1, 1990, were 80 per cent and 42 per cent for the industrial areas of Kwai Chung and Kwun Tong respectively.
For those monitoring stations located close to industrial areas, some reduction in the concentrations of nitrogen oxides and the suspended particulates was also observed after July. However, the levels of both total and respirable suspended particulates were still high throughout the territory. High levels of rainwater acidity were measured on several occasions but levels of photochemical oxidant remained low throughout the year.
To strengthen the enforcement capability of the Air Control Group, the EPD acquired and commissioned in July a mobile Stack Emission Monitoring Laboratory.
Stack emission monitoring at Tai Po was carried out using the mobile laboratory this year. Levels of sulphur dioxide, nitrogen dioxide, carbon monoxide, ozone, and total and respirable-suspended particulates were within the Hong Kong AQOS during the short monitoring period. However particulate levels were on the high side and if the same level of total suspended particulates were recorded throughout the year, its annual air quality objective would have been exceeded.
The enforcement work is further facilitated by the development of a computerised Enforcement Management System (EMS), which is designed to provide management control of enforcement functions and to establish standardised methods of data retrieval/ processing. A comprehensive survey of the combustion sources was started early in 1990 to obtain an updated computerised database so that timely emission information can be made readily available for various enforcement programmes.
Subsequent to the territory-wide screening tests for indoor radon levels in 1988, the EPD carried out a one-year follow-up study which was completed by the summer of 1990. Radon is a radioactive gas which is reported to cause cancer. It is produced from disintegration of trace amounts of radioactive elements in natural materials. When the study results have been fully analysed, appropriate measures may be needed to reduce any health risks.
Noise Control
In addition to the enforcement of the Noise Control Ordinance, the EPD is implementing noise abatement projects in stages. Under the noise abatement programme in schools, which is funded by the government, schools seriously affected by aircraft or traffic noise will be insulated. This year marked the completion of the insulation programme against aircraft noise for 38 schools at a total cost of about $75 million. Following this successful programme, 29 schools which were seriously affected by traffic noise have been insulated at a total cost of about $36 million, and a further 87 schools will be insulated in the coming two years at an estimated cost of $65 million.
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