Beijing is seeking to tame its infamous smog by preparing emergency measures such as factory shutdowns and traffic limits to kick in when air pollution levels are especially heavy.
The city government said yesterday that the strictest measures will take effect when the smog index for fine particulate matter, PM2.5 - the tiny airborne particles considered most harmful to health - is forecast to exceed 300 micrograms per cubic metre for three days running. The World Health Organisation safe limit is 25 micrograms.
Private vehicles will be allowed to operate only on alternating days, depending on the last number of their licence plates. Factory emissions will be cut 30 per cent by suspending or limiting production, and construction sites must halt excavation and demolition. Classes will be suspended, a measure likely to cause inconvenience in a city where most parents both work.
The measures require precise pollution forecasting and timely public notification to be effective, and there was obvious scepticism in the questions asked by reporters at a briefing.
The measures apply only to Beijing, despite the fact that as much as 60 per cent of the city's air pollution wafts in from neighbouring provinces. "We have no control over Hebei , but this is a national priority and we hope we can be a positive role model," said Fang Li , deputy director of the Environmental Protection Bureau.
A sprawling city of more than 20 million, Beijing saw air pollution levels spike this year despite the imposition of more than 100 control measures that are enforced with varying strictness.
Vehicle emissions are blamed for about a quarter of the pollution, with coal-fired plants and factory production blamed for most of the rest. Odd-even licence plate traffic restrictions and limits on industrial activity were first rolled out as temporary measures during the 2008 Olympics, after which the city enjoyed a brief improvement in air quality.
Watch: The smog shrouding Beijing from atop the Forbidden City
Elsewhere yesterday, thick smog enveloped Harbin , capital of Heilongjiang province for a third day, with schools and its airport shut and low visibility forcing ground transport to a halt in places.
Flights remained severely delayed, after more than 250 flights were cancelled. Concentrations of PM2.5 reached 822 micrograms per cubic metre yesterday.
Associated Press, Agence France-Presse