Bacteria are feeding and multiplying in the severe smogs that regularly blanket Chinese cities. The microorganisms could pose a threat in themselves and may also change the composition of the haze.

China’s capital Beijing is regularly smothered in a thick, toxic haze that forms as a result of coal burning, vehicle exhausts and other sources . It is worst in winter, when weather patterns trap pollution over the city. China has cracked down on emitters, and in 2018 emissions fell 12 per cent , but there …