Beijing has issued its first air pollution "red alert", triggering a series of measures to curb emissions and safeguard public health, a week after the city suffered its worst smog this year.
Half of the capital's private cars will be ordered off the roads today and all schools will be urged to close, as part of emergency response measures introduced in 2013.
Outdoor construction, fireworks and barbecues will also be banned. Polluting factories will have to limit or cease operations, while heavy transport vehicles and trucks will not be allowed on roads. "Construction waste, excavation transport vehicles, cement trucks, gravel transport vehicles and other large-scale vehicles are prohibited from driving on roads," the authorities said in the notice.
The measures will stay in place until Thursday, when a cold front is expected to disperse the bad air.
The unprecedented move to issue the highest alert level comes after the local government was widely criticised for issuing only a lower, orange alert level last week, although levels of PM2.5 - harmful microscopic particles - hit 634 micrograms per cubic m on Dec 1.
That was the worst air Beijing suffered in more than a year, and represents a PM2.5 level more than 25 times above the maximum limit recommended by the World Health Organisation.
For consecutive days last week, the capital of 22 million was shrouded in smog and, following a brief respite, smog at "very unhealthy" levels returned to Beijing yesterday. Schoolchildren were forced to stay indoors and many schools allowed parents to keep their children at home, local media reported.
The worsening air quality has cast doubt on China's ability to tackle the problem, amid its well-publicised pledges to rein in carbon emissions.
Pollution has also become a major source of unhappiness among Chinese urban residents, and a China Daily editorial yesterday said a car congestion fee had to be implemented immediately.
"The severity of the city's traffic and pollution problems leaves no time for policymakers to postpone such moves," it said.
On Sunday, Chinese Environment Minister Chen Jining vowed to strictly punish agencies or personnel who failed to initiate an emergency response plan in a timely manner.
But reflecting the wider anxiety among the public, one Chinese netizen wrote on Weibo: "Two days of smog, two days clear, two more days of smog... take care of yourselves, everyone."