Acid rain is caused largely by sulfur dioxide and oxides of nitrogen emitted by industrial activities such as coal burning. The gases dissolve in rainwater to form acids. Much of this industry is based in the United States, but the weather exports pollution north of the border. Between 50% and 70% of Canada's acid rain comes from the United States, while only 2-10% of America's pollution in this area comes from Canada.
- Taken from Nature, Acid Rain Still Hurting Canada By: Michael Hopkin
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