Doing our best to fight air pollution

THE report about the launch of Hong Kong's Air Pollution Index, 'Officials stand by rooftop monitoring of air pollution' (South China Morning Post, June 6), said that green groups have accused the Government of giving people a false sense of security because an air pollution reading from a 20-storey building will be less dramatic than if taken from the ground.

I am not sure where the green groups gained the impression that our monitoring stations are on the top of 20-storey buildings. It was stated several times at the launch ceremony that our monitoring stations are located on the fourth to sixth floors with actual heights between 17 and 25 metres, and that these heights are similar to those used for index monitoring purposes in many cities around the world. The Air Pollution Index is also basically the same as that used, for example, in California, Canada, Australia and Singapore.

Having said that we would be the first to admit that it is extremely difficult to formulate a single index that reflects the widely varying levels of air pollution to which members of the community can be exposed. In the absence of a better alternative, we have adopted the current international practice.

So if our API shows that the air quality on a particular day is 'good', then this is what the report would be had the same measurements been made in many cities elsewhere in the world.

Let me assure your readers that we are in no doubt about the need to improve the air quality in Hong Kong, not to mention preventing any further deterioration as a result of increasing numbers of vehicles on the road.

Our main concern is the level of particulate matter in the atmosphere, especially very fine particles, as well as oxides of nitrogen. Diesel-engined vehicles are a major source of both these pollutants.

Measures introduced so far to attack air pollution from motor vehicles include the smoky vehicles spotting programme, which resulted last year in more than 27,000 vehicles being hauled in for testing, of which more than 1,500 were delicensed; the introduction of unleaded petrol and the requirement that all new petrol-engined vehicles are fitted with catalytic converters; the requirement as from April this year that automotive diesel fuel contains less than 0.2 per cent sulphur; and that heavy diesel-engined vehicles meet the most stringent European and American emission standards.

A number of other measures are being considered which should ensure that we can beat the threat of deteriorating air quality.

C. W. TSE for Director of Environmental Protection