We've been writing a lot about the record levels of smog in Shanghai lately. Thanks to a combination of weather and other factors it's gotten to levels that are genuinely hazardous to health.

Observed at 08:00, Tuesday 25 March BBC Weather in association with MeteoGroup, external All times are China Standard Time (Asia/Shanghai, GMT+8) unless otherwise stated.

Lahore, the provincial capital of Punjab, tops the index, with pollution reaching levels ten times higher than those in Shanghai early ... a major cause of the toxic smog that hangs over the ...