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Heat warning well and good, but what about the killer air?


Howard Winn
Aug 02, 2012

Good to see that the observatory issued a hot weather warning yesterday. This advised that, to prevent heat stroke, people should avoid prolonged activities outdoors. If you were outside, you should have been wearing a wide-brimmed hat and light-coloured, loose-fitting clothes and staying in shaded areas as much as possible. The observatory’s press statement urged television and radio to issue the warning as soon as possible. However, it is a shame there was no urgency attached to a far bigger threat – the air pollution levels.

The government’s air pollution index had all pollutants as “very high”. Given that these levels haven’t been adjusted since the 1980s, they are way out of date and way below the World Health Organisation (WHO) guidelines. The Environmental Protection Department’s advice for yesterday’s pollution levels was for children, the elderly and people with existing heart or respiratory illnesses to avoid prolonged stays in areas with heavy traffic and to reduce physical exertion in such areas as far as possible.

According to the department’s website, the respirable suspended particulates (RSP) at roadside level in Central between 8am and 6pm yesterday ranged between 23.9 and 171.7 micrograms per cubic metre (mcm). The WHO guidelines stipulate that, over a 24-hour period, a safe level is 50mcm. Above that level, the pollution begins to affect health.

The Hong Kong government’s 24-hour level is 180mcm. So levels of RSP were as much as three times higher than WHO guidelines, and more. Nitrogen dioxide levels were also high, ranging between 173 and 513mcm, more than twice the WHO guidelines of 200mcm per hour – and thus more than twice the levels at which NO2 begins to affect one’s health. The Hedley Environmental index, which can be found at, was off the scale yesterday, with its pointer past the “very dangerous” level.

We also hear from Professor Anthony Hedley at the University of Hong Kong that the medical literature is now replete with studies on health impacts, especially in maternal and child health, with diverse and serious outcomes such as leukaemia, congenital heart disease and growth retardation in pregnancy at levels considerably lower than the current WHO annual limit. He has recently shown that compliance with the present short-term limits for NO2 will not achieve the annual limit of 40mcm in a high-pollution environment like Hong Kong.

The air pollution we are discussing here is roadside pollution, which is created in Hong Kong and can be tackled by a government with political will. The main sources are buses and trucks with old diesel engines.

The government’s disregard for public health in this area is scandalous, particularly for a territory that likes to style itself as Asia’s world city. We await with some interest to see if the new Environment Bureau chief has any intention of doing something about this

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