One of the most popular iPad apps in Beijing at present is China Air Pollution Index. The app is both addictive and disturbing. When I checked into a Beijing hotel recently, I found that – even from the 40th floor – I couldn’t see further than one block because of the grey smog enveloping the city. So I checked the numbers and discovered that the AQ level, which measures fine particulates that are especially dangerous, was 250 – about five times the level deemed safe.
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