Indoor air quality study is needed urgently

PUBLISHED : Sunday, 14 October, 2007, 12:00am
UPDATED : Sunday, 14 October, 2007, 12:00am

Children and elderly people are, sensibly, advised to avoid outdoor activities on high-pollution days. Not so much attention, however, has been paid to indoor pollution. The quality of the air inside our buildings may not be much better. As we report today, a study conducted on behalf of the Sunday Morning Post has found classrooms in three out of four schools monitored have high levels of respirable suspended particulates. This is the type of pollution most harmful to children. Even more worrying is the finding that indoor and outdoor pollution levels at three of the schools tracked each other so closely that children were exposed wherever they were.

As University of Hong Kong public health expert Anthony Hedley has said, there is no difference, in terms of the risk to health, between exercising outdoors and indoors in a high-pollution environment. The danger, however, is that school officials may not be aware of the health risks indoors, even when they act responsibly and keep pupils from activities outside the classroom.

The latest study is only a snapshot profiling a single type of pollutant and cannot be directly compared with the government's composite index of six polluting chemicals. The methods by which the readings are calculated are different. But the high levels of indoor pollution recorded in our study should be sufficient to raise alarm bells. The fact that indoor pollution levels rose when the API went up and - especially - the discovery that indoor levels were not much better than those outside are telling.

The government should launch an in-depth study of its own to establish clearly and comprehensively how much indoor pollution poses a threat to health. Then, depending on what the study reveals, corrective measures and up-to-date advice can be provided.

Critics have already drawn attention to the government's outdated guidelines - which call on schools to reduce outdoor activities for students when the air pollution index exceeds 200 - saying they are set unrealistically high. More schools are making decisions on their own to cancel outdoor activities well below that level. But this may not be enough if indoor air quality is not much better. There is clearly a need for a better understanding of the position.

Measures to help us cope with pollution levels should run alongside wider efforts to improve air quality. In his policy address last week, Chief Executive Donald Tsang Yam-kuen showed concern about pollution and announced several measures aimed at combating it. He later described it as a priority for the government. Every effort must be made to bring pollution levels down.

There was, however, no mention in the policy address of reforming the existing pollution monitoring system. The government is dragging its feet on introducing stringent standards set by the World Health Organisation. But even the WHO admits it is behind when it comes to understanding and recommending policies and guidelines on indoor air quality. It clearly recognises the dangers, though. It is working on these to supplement its complete programme for outdoor air quality.

A government study of the issue is needed so that schools - and the public - can be alerted to the potential dangers and given advice on measures to mitigate them. Improving the use of air conditioning and air filters could be done relatively quickly. The protection of children's health is a top priority. Action should not be delayed.