Heavy smog shrouds the second ring road in Beijing, 21 January. The government had hoped that rain and snow would disperse the smog that has blanketed the city since last weekend, but an index monitoring of PM2.5 particulates revealed that it still stood at 400 in some parts of the city - down on last week's record score of 755, but still well above levels deemed hazardous to human health

Photograph: ADRIAN BRADSHAW/EPA