Beijing again shrouded in smog after brief respite

Heavy smog returned to the capital yesterday, with the air pollution reading at the US embassy hitting 429 in the late afternoon, up from 173 the day before.

A reading above 300 is deemed "hazardous" by both mainland and American standards and all residents are urged to avoid outdoor exercise.

It's the second time the embassy's reading has risen above 400 since world leaders left Beijing after the Asia-Pacific Economic Cooperation summit ended on November 11.

Beijing had some relief from the smog early this month after authorities closed factories in surrounding provinces and reduced the number of vehicles on the road for the summit. But pollution re-emerged as the city returned to business as usual.

The municipal environmental bureau's air quality index reading was below 300. The Beijing Meteorological Bureau issued a yellow smog alert - the lowest in a three-tier warning system - in the early hours of yesterday. Weather was "very adverse for pollutants to be diluted, dispersed and cleaned up" due to low winds, the forecast said.

Conditions were expected to ease today as a cold front pushed winds towards the capital, the bureau said.