http://sph.hku.hk/hedleyindex.

Air pollution makes exercise dangerous to health on 335 days per year
Hong Kong University public health expert voices concerns

Hong Kong’s average pollution levels are so high that in recent years there have been only about 30 days per year when it would be truly safe to do exercise, according to research carried out by public health experts from Hong Kong University (HKU).

This troubling assessment is based on the number of days and the amount by which our air pollution exceeds the World Health Organisation’s Air Quality Guidelines (WHO AQG). It also takes into account that exercise causes faster and deeper breathing, increasing exposure to pollution and amplifying damage to the body.

“Anyone taking exercise in Hong Kong needs to be aware of the risks air pollution poses to their health,” said Professor Anthony Hedley of the School of Public Health, Department of Community Medicine, HKU. “People here are caught in an impossible dilemma – regular exercise is absolutely necessary for good heath - but most of the time it also increases exposure to the harmful effects of air pollution.”

Professor Hedley suggested, as a rough guideline, that sports and energetic outdoor activities should be cancelled when the levels of pollutants such as particles and nitrogen dioxide reach around 100 micrograms per cubic metre. This does not mean that pollution levels below 100 micrograms per cubic metre but still well above the WHO guideline are safe, only that the risks are less likely to be severe.

A new website – The Hedley Environmental Index (named in honour of Professor Hedley) – provides real-time data on pollution levels, allowing athletes to assess for themselves the risk associated with taking exercise on a given day and in a number of locations around Hong Kong. The Index also provides information based on peer-reviewed research on the health impacts and costs caused by pollution

“Certainly, any level of pollution above the WHO AQG poses some health risk. Therefore, the problem becomes one of determining an acceptable level of risk and trying to lead a normal life,” added Professor Hedley.

The WHO AQG, based on the world’s best studies of the impacts of air pollution, are much tighter than Hong Kong’s own guidelines – the Air Pollution Index (API) Thus the API-based warning levels, despite grading pollution from ‘low’ to ‘severe’, routinely understate the threat to public health.

The Hedley Environmental Index (released on 18th December) will be demonstrated at a public conference Civic Exchange is organizing on Saturday 10th January to discuss the status and possible solutions to Hong Kong’s air pollution. For registration and more information, please visit: The Air We Breathe – A Public Health Dialogue.