HONG KONG — Twenty-two people were taken to hospital and two of them were in critical condition after taking part in Hong Kong's biggest marathon amid the worst air pollution levels in months, the government said on Monday.

A record 40,000 people took part in Sunday's Standard Chartered Hong Kong Marathon and many complained of the thick smog which obscured the Tsing Ma Bridge, a key landmark along the route of the annual race.

Of the two runners in critical condition, one collapsed near the finish in Wanchai district, an area where the air pollution index (API) soared to nearly 150, the highest level since September 2005. The other collapsed not far from the Tsing Ma Bridge.

"They are still in critical condition," a government spokeswoman said.

The organiser, the Hong Kong Amateur Athletic Association, was not immediately available for comment and it was not clear if the two men collapsed because of polluted air.

However, Choi Kin, president of the Hong Kong Medical Association said their condition was more likely to be linked to their level of fitness rather than air quality.

"When people suddenly perform exercise that aims to test their limits, their bodies may not be able to cope," the South China Morning Post reported Choi as saying.

Hong Kong uses the API to gauge its air quality, which has worsened in recent years. Many days of the year, the tiny city in southern China is shrouded in smog and people can hardly see across the famous Victoria Harbour.

Environmentalists blame the air pollution on emissions from vehicles in the territory and factories in southern China.

Source: Reuters