'Severe' pollution recorded as smog shrouds Beijing

High levels of tiny airborne particles were recorded at Beijing's 35 pollution-monitoring stations yesterday as the capital was blanketed by heavy smog on the first working day after the eight-day National Day holiday.

Beijing's environmental authority said on Saturday that the city had completed upgrading the monitoring network so that it could give a more accurate measure of the city's air quality, with all 35 stations now releasing real-time data on cancer-causing respirable suspended particulates - known as PM 2.5.

The monitors, scattered in central Beijing and its suburbs, will run for a three-month trial, before the city's environmental authority formally begins using PM2.5 as a gauge of the city's air quality, rather than the larger particles it currently measures.

The smaller particles are considered more critical because they can embed themselves deep in the lungs and the bloodstream.

Concentrations of PM2.5 reached 274 micrograms per cubic metre at 6pm yesterday, with air quality officially rated "severely polluted".

Pedestrians were seen wearing masks for protection from the choking smog, which reduced visibility in the south of the city to about one kilometre.

The US embassy, which measures air quality from its rooftop, tweeted that its PM2.5 reading - 308 micrograms per cubic metre at 6pm - was "hazardous".

Beijing residents lamented the poor air quality on microblogs, with some blaming increased traffic for the high pollution readings after days of clear skies during the holiday.

The city's environmental authority said the severe pollution was due to a lack of wind to disperse the pollutants, but the situation should improve today, with wind and rain expected.

Beijing only started releasing PM2.5 data in January.

The long omission of such data from the mainland's pollution parameters sparked a national outcry last year over the government's secrecy about smog problems in major cities.

Professor Hao Jiming, an environmental expert from Tsinghua University, said it may take Beijing a decade or even longer to bring air quality readings to safe levels.