About 300,000 high-pollution vehicles will also be restricted from entering the city starting next month, he said.

Beijing and dozens of cities in China spend many winter days under a thick, gray haze, with air pollution levels that routinely exceed World Health Organisation guidelines. Beijing spent part of last week under an “orange alert,” the second-highest level in China’s four-tiered air alert system. More than 20 cities were on the highest “red alert”.

Smog is an acutely felt issue in China’s cities, where a “red alert” can lead to the closure of schools and businesses, flight cancellations and shutdowns of highways to keep cars off the roads.

During a red alert in Beijing last month, the authorities banned construction crews from spray-painting and even seized the charcoal grills from some restaurants.

But enforcement remains an issue. China’s environmental ministry said during last week’s red alert that its inspection teams found companies resuming production despite a government ban. Many factories remain under severe pressure to meet production targets regardless of air pollution.

Cai blamed polluting activities like burning garbage or wood on “the result of lax supervision and weak law enforcement”.

But China’s pollution is caused chiefly by its thousands of coal-burning factories and a surplus of older, inefficient vehicles. While it tries to answer the loud public calls to tamp down on pollution, China’s Communist government is also grappling with an economic slowdown and the challenge of maintaining growth.

China is also the world’s largest producer and consumer of coal, and measures like capping production days or shutting down older coal mines run the risk of driving up energy prices and further slowing the economy.