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THE ENVIRONMENT
vessels moored in Victoria Harbour and dwelling boats in typhoon shelters. To combat oil pollution, the department operates a purpose-built pollution control vessel and has stocks of low toxicity chemical dispersants, and more than 2 400 metres of large and medium size oil containment booms.
Monitoring and Investigations
In order to establish the appropriate level for environmental controls in Hong Kong and to plan properly for future noise, air, water and waste management schemes, the EPD operates a comprehensive monitoring programme and undertakes investigations on envi- ronmental quality throughout the territory. The department has continued to operate the existing six continuous air quality monitoring stations to acquire air quality data for planning and control purposes. In line with the declaration of the Tsuen Wan-Kwai Chung Air Control Zone, one new air quality monitoring station was installed and commissioned in Kwai Chung and another temporary station was installed in Tsuen Wan. Work has started to establish a full scale permanent station in Tsuen Wan.
The department has plans to expand the air quality monitoring network to cover the whole territory. Work has started on establishing a new monitoring station in Sha Tin to obtain air quality data to prepare for the declaration of an Air Control Zone there. Work has also started on enhancing the telemetry system to cater for the expansion of the air quality monitoring network. All continuous air quality measurements made at the remote stations are telemetered to the EPD's central computer for processing and reporting.
During 1988, the long term levels of sulphur dioxide in the atmosphere remained acceptable in most urban areas but the short-term air quality objective was exceeded on a few occasions at the Kwun Tong station. Levels of nitrogen dioxide were slightly lower than in 1987. However, there were a few occasions on which the short-term nitrogen dioxide objective at the Kwun Tong and Central and Western stations was exceeded. Levels of photochemical oxidant remained low during the year. High levels of total and respirable suspended particulates were measured at all monitoring stations and all exceeded the annual air quality objectives. Moreover, high levels of rainwater acidity were recorded on several occasions and a comparatively high sulphate deposition rate in rain was recorded at the Kwun Tong station. Air quality management plans are to be formulated to tackle these air quality problems in air control zones.
As a supplement to the fixed-site monitoring network which aims at measuring the long-term trend of air quality within a district, short-term air quality studies were carried out in selected industrial, residential, and other special locations. A three-month study by a specially designed mobile laboratory in Sha Tin revealed generally acceptable air quality. However, the level of odorous gases, as indicated by hydrogen sulphide concentration, exceeded the odour threshold, suggesting that although not exposed to a health risk, people living in the vicinity of monitoring locations were subjected to a distinct environmental nuisance. The mobile laboratory was also used for monitoring air quality in Tsing Yi Island. In addition to other ongoing projects, monitoring of lead levels in airborne particles and roadside dust continued after the reduction of the amount of lead in gasoline to 0.15 gram per litre in July 1987. The results indicated a continued downward trend which was initiated when the lead reduction programme started in 1981 (at which time the amount of lead in gasoline was 0.84 gram per litre).
With the area's first nuclear power station now under construction at Daya Bay, there is growing public concern over the possibility of radioactive pollution. To provide the data against which to assess any changes in the radiation environment, a Background Radiation