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THE ENVIRONMENT
The first trials with the batch-type drier were made with pig manure and the results compared with those from the rotary-type drier. At the Ta Kwu Ling Pig Breeding Centre, investigations into slurry treatment continued and, in September, work was completed on an extension that included a second aeration pond and two biochemical filter towers for improving farm liquid wastes.
Work on manure handling, storage and transport problems involved the siting and building of the first collection and storage bunkers, designed for both solids and liquids, and manure pre-drying trials aimed at cheapening treatment by driers.
Air Pollution
Records taken at the four daily monitoring stations operated by the Labour Depart- ment Air Pollution Control Unit during 1977 continued to show a significant reduction in sulphur dioxide concentrations. At Hung Hom, the level of sulphur dioxide was about one 60th of the maximum permitted level of 1,310 ug/m3. Readings at the Queen Elizabeth Hospital station were about 43 ug/m3 while readings at Sham Shui Po and at the Central Market were about 12 ug/m3. Smoke density readings at the four stations showed no substantial increase over the previous year's figures.
A three-month environmental survey of pollution levels, similar to that carried out in 1976, was jointly conducted by staff of the Air Pollution Control Unit and second-year students of the University of Hong Kong chemistry department. Con- centrations of sulphur dioxide, nitrogen oxide, carbon monoxide and particulates were monitored at different levels in busy streets and in industrial areas.
During the year, the unit handled 1,029 air pollution complaints from the public. Although the unit finds that constructive advice is usually more effective than stringent enforcement, prosecutions under the Clean Air Ordinance and its subsidiary regula- tions against persistent offenders are still necessary. In 1977, there were 73 convictions with fines ranging from $100 to $2,150.
Chimneys at the Kennedy Town incinerator were fitted with nozzles to improve dis- persion during the year. Work to raise by 30 metres the height of the chimney at the Lai Chi Kok incinerator began in September. The dispersion of waste gases will be much improved when the work is completed by mid-1978. A new incinerator, equipped with modern pollution-reducing equipment, is being built at Kwai Chung. Sections of the Road Traffic (Construction and Use) Regulations were amended in March to allow the police to make roadside checks on vehicles emitting excessive exhaust smoke. A publicity campaign, organised jointly by the government and EPCOM, was held to publicise the new regulations and to impress on motorists that properly maintained vehicles emit less exhaust smoke. Under the new legislation, an owner can be summonsed if a vehicle emits smoke above the permitted level.
Noise Pollution
Legislation to control noise from air-conditioning plants came into force in February, 1977. Special training courses on noise control were arranged for Urban Services Department health inspectors to enable them to enforce the legislation and to prepare them for future responsibilities in controlling noise pollution from stationary sources. With the recovery of the economy, public and private building accelerated during the year. As a result, the problem of construction noise attracted many complaints,