Bad air cuts visibility in Hong Kong, raising death rates

HONG KONG (Reuters) – Visibility in Hong Kong has deteriorated so sharply over the last 50 years because of air pollution that variations in levels can even be used to predict mortality rates, health experts warned on Wednesday.


Visibility is now 12.6 km (7.8 miles) on an average day, well below that of cities such as Paris, Berlin, Auckland and Vancouver, where visibility stands at 20 to 25 km or beyond.


Using government data, researchers at the University of Hong Kong found that the number of hazy days when visibility fell to below 8 km shot up to 54 in 2007 from 6.6 in 1968.


For every 6.5-km reduction in visibility, there was a corresponding 1.13 percent increase in the number of non-accidental deaths from such causes as heart and respiratory diseases.


These additional deaths worked out to a total of 1,200 per year between 2007 and 2010, the experts told a news conference.


"Loss of visibility is a direct measure of serious harm to health. Loss of visibility kills people," said Anthony Hedley, Honorary Professor at the School of Public Health.

Professor Lam Tai-hing, director of the School of Public Health, said: "The less you can see, the greater the harm. It is very important to believe in your eyes because at the moment, the government is still using outdated air quality objectives.


"Based on that, people are being told today's air quality is good or acceptable when in fact, if you follow the World Health Organization's air quality guidelines, it is very bad indeed."


Poor visibility was due to the concentration of pollutants such as respirable suspended particulates and nitrogen dioxide, Hedley said.

While the amount of particulates in places like Vancouver and Auckland measured between 10 to 12 micrograms per cubic meter of air, Hong Kong had 80 micrograms per cubic meter.

"The higher the pollutant concentrations, the lower the visibility," Hedley said, adding that even short exposure to such pollutants was particularly dangerous for those suffering from underlying heart or lung illnesses.
"Air pollutants increase the stickiness of elements in the blood ... With increased stickiness, blood cells stick together, they form a clot. If you form a clot, you may obstruct a vessel and if the vessel is in the heart or the head, you get a heart attack or a stroke," Hedley said.
"In people who are susceptible, such as those with diabetes, they begin to experience serious degradation to their health, they will become sick and may have a shorter life expectancy."