HK chokes as China smog threatensTop News | Chan Ho-him and Phoenix Un 9 Jan 2017
Pollution rose to the "serious" level across Hong Kong yesterday, climbing in Tung Chung and Tuen Mun as smog enveloped the Pearl River Delta region.
The Environmental Protection Department said the Air Quality Health Index reached the "very high" risk category, which is hazardous to children, the elderly and people with heart or respiratory illnesses.
The department said: "According to the Hong Kong Observatory, a replenishment of the northeast monsoon will bring windier and slightly cooler weather in the next few days. It is expected that pollution levels will remain higher than normal until then."
Concern groups in Hong Kong said most pollutants did not come from the mainland but mainly resulted from local pollutants such as traffic.
Dry and sunny weather in the Pearl River Delta yesterday with low to moderate northerlies favored the formation of photochemical smog, causing ozone and PM2.5 to quickly build up and accumulate in the area, the Environmental Protection Department said.
Facing northwesterly winds, areas including Tung Chung were affected by an airstream with higher background pollutant concentrations from the Peal River Delta area, causing ozone and PM2.5 to build up.
At 4pm yesterday, Hong Kong's monitoring stations recorded air quality figures as high as 198 n Tuen Mun and 195 in Tung Chung.
A level between 151 and 200 is classified as "unhealthy," meaning people with breathing or heart problems should reduce outdoor exercise.
The Air Quality Health Index at 12 out of all 16 general and roadside monitoring stations reached "high" or "very high" at 7pm.
The index recorded "very high" in Tung Chung, Tuen Mun, Yuen Long, Tsuen Wan and Causeway Bay.
The EPD said Hong Kong was being affected by an air stream with higher background pollutant concentrations.
"The light wind hinders effective dispersion of air pollutants," it said.
"The sunshine enhances photochemical smog activities and the formation of ozone during the daytime, resulting in high pollution in the region.
"The high level of ozone has promoted the formation of nitrogen dioxide, particularly in parts of the urban areas and at the roadside."
Mrs Yuen, a housewife who has been living in Tuen Mun for more than two decades, said: "On normal days we can see the airport [at Chek Lap Kok] across the harbor, but with a northerly wind we usually can't.
"It becomes very blurred."
An expatriate who has been living on the Gold Coast for the past nine years said it had been smoggy for the past two days.
Fine pollutant particulates PM2.5 - active suspended particles in the air, which are a key contributor to the Beijing smog - were 141.3 micrograms per cubic meter of the air at Tung Chung and 113.1 at Tsuen Wan by 4pm yesterday.
The World Health Organization's standard is 25 micrograms per cubic meter of air.
"Northerly winds in the New Territories were observed yesterday afternoon but southerly winds were observed in Kowloon, meaning pollutants could be trapped within Hong Kong as dispersion of air pollutants was ineffective," said Clean Air Network's community relations manager Loong Tsz-Wai.