Smog red alert

Beijing has issued a second pollution red alert, little more than a week after the first ever such warning.

The Chinese capital will see hazardous smog from today until Tuesday, the official meteorological service said.

Nationwide, a vast area from Xian in central China to Harbin in the north-east would also be badly hit, the National Meteorological Centre said.

Beijing authorities have advised residents to avoid outdoor activity and for schools to stop classes.

The red alert - the highest of a four-level alert system instituted two years ago - also triggers restrictions on vehicle use, factories and construction work.

The government has promised to take action to address often dangerous levels of pollution.

Long-term exposure to high levels of PM2.5 - the dangerous particulate matter in smog - has been linked to lung damage and respiratory illnesses.

The World Health Organization considers PM2.5 readings of 25 micrograms per cubic metre as the maximum safe level. The smog which hit Beijing on 8 December peaked just below 300. Residents are encouraged to stay indoors if levels exceed that level.

Meteorological authorities have said this time the smog is expected to exceed 500 micrograms per cubic metre.

Authorities released a map showing that smog would blanket a swathe of the country spanning nearly 2,000km, encompassing at least 12 major cities, with Beijing and nearby city Shijiazhuang heaviest hit.

The news of the new red alert was greeted with exasperation and worry among Chinese citizens.

Beijing resident Cheng Xianke expressed concern for the health of the elderly and children. He told Reuters: "For us who commute to work it's not so bad but still I'm very concerned about the pollution. I think the government needs to put more effort into solving this."

Another resident, Fan Xiaoting, told the news agency that the alert would affect school teaching timetables: "We are paying close attention as to whether stopping the classes will have further implications."

Coal-powered industries and heating systems - in heavy use during the cold Beijing winter - are major contributors to the smog.