China closed dozens of factories and restricted the use of government vehicles on Monday in a bid to reduce a three-day run of record levels of hazardous air pollution in Beijing, Bloomberg reported. Shijiazhuang, a nearby northern Chinese city, removed 30% of official cars from use to reduce pollutants, said the local government in an online statement on Monday, after Beijing made similar orders. Fifty-eight factories in Beijing stopped production temporarily, China.com.cn said on Monday, citing a Beijing official. The amount of PM2.5 particles, the smallest and most harmful of pollutants, in the atmosphere was as high as 993 micrograms per cubic meter in Beijing on Saturday, according to official measures. A measure of under 25 is recommended by the WHO. Environmental protection companies appear to have benefited from the wave of pollution, as their stocks surged to impressive levels, on investor presumptions that business may improve with a government push to curb pollution.