Smog sources
Athletes raised concerns about breathing the toxic smog during the Olympics, but Beijing's residents have to live with it all the time.
Diesel car engines, factories and the burning of dirty fuels such as coal and dung produce thick, sooty smoke. This creates a haze that often blankets many of the world's large cities, and is known to be bad for people's health.
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Los Angeles also experiences smog - and it receives very little rainfall to help clear the skies.
Image: Ben Amstutz |
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