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The 10 worst pollution problems in the world

Oct. 16, 2009, 11:21 p.m.
A young boy stands outside his shanty home in Calcutta, India

Photo: Jeff Morse/iStockphoto

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Indoor air pollution

A young boy stands outside his shanty home in Calcutta, India, where much of the energy to cook, heat and light the house comes from burning coal, wood and animal dung. The smoke from these fires is one of the developing world's main causes of indoor air pollution.