Vice-premier calls for immediate action as capital can learn from experience of other major cities that tackled pollution, report Zhang Chunyan in London, Chen Jia in San Francisco and Wu Wencong, Tang Yue in Beijing.

China will strengthen the enforcement of environmental laws, and take other measures to tackle air pollution, Vice-Premier Li Keqiang pledged on Tuesday.

A resident wears a mask to protect herself from the polluted air while riding on a road in Zhengzhou, Central China's Henan province on Monday. [Photo/Xinhua]

"We published accurate PM2.5 data. It took a long time for this problem to accumulate, and it will take a long time to solve it," he said.

"But we must act! We have to strengthen the enforcement of environmental

laws and other regulations and also remind the public to protect themselves."

Beijing has been shrouded in thick smog since Saturday. Levels of PM2.5 — particle matter smaller than 2.5 microns and able to enter the lungs and even the bloodstream — passed 300 micrograms per cubic meter on Saturday in 33 of the 74 cities with systems sensitive enough to monitor the particles. The World Health Organization considers the safe daily level to be 25 micrograms per cubic meter.

On his Sina Weibo account, John Ross, a former adviser of ex-London mayor Ken Livingstone and who now lives in Shanghai, said he was reminded of the Great Smog of 1952 in London. That incident claimed 4,000 lives over a period of two weeks and claimed a further 8,000 lives during the following months.

Meanwhile, Thomas Unnasch, a medical professor in San Francisco, thought of Los Angeles in the 1960s, even though the city's air at the time was cleaner than during the period of severe air pollution, known locally as the "gas attack", which caused 2,000 auto accidents in a single day in 1954.

China Daily canvassed the opinions of a number of international experts with regard to the action that can be taken to avoid the severe pollution that plagued London, LA and other cities half a century ago.

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