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Press Release
Very high air pollution indices forecast for next few days
The Environmental Protection Department (EPD) recorded very high Air Pollution Indices (API) of 125, 102 and 108 at the Tung Chung, Yuen Long and Central/Western general air quality monitoring stations respectively at 3pm today (September 12) due to high ozone concentrations. At the roadside, the API at Central station also reached 115 due to high concentrations of nitrogen dioxide.
A spokesman for the EPD said that it was expected that the general and roadside API readings would remain at higher than normal levels in the next couple of days.
Under the combined effects of a continental airstream and Typhoon Sinlaku now located near Taiwan, the weather over South China region was fine and hot, and the wind was light today. Air pollutants in Hong Kong and the Pearl River Delta region were trapped under the light wind, the sunny and hot weather conditions favoured the photochemical reaction of pollutants to form ozone in the region, resulting in elevated ozone levels which pushed up the API at the general stations in the afternoon.
At the roadside, pollutants emitted from motor vehicles could not disperse effectively under the calm wind conditions. With the elevated background ozone concentrations, the nitrogen oxides emitted from motor vehicles were readily oxidised to form nitrogen dioxide. "We therefore saw very high API readings at the roadside due to high concentrations of nitrogen dioxide," the spokesman said.
According to the Hong Kong Observatory, the weather will remain fine and hot with light wind in the next few days. Dispersion of air pollutants will still be poor and photochemical smog reactions will continue to be active. "We expect that air pollution levels will stay high for the next couple of days."
With an API in the very high range, people with heart or respiratory illnesses should reduce physical exertion and outdoor activities, and avoid prolonged stay in streets with heavy traffic.
The public can check the latest hourly API readings for different locations on 2827 8541 or from EPD's website at http://www.epd-asg.gov.hk.
Ends/Friday, September 12, 2008
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