| pollution | <ecology> The changing of a natural environment, either by natural or artificial means, so that the environment becomes harmful to the living things normally found in it. most often this refers to the input of toxic chemicals into the environment. (09 Oct 1997) |
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| air pollution, indoor | The contamination of indoor air. (12 Dec 1998) |
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| tobacco smoke pollution | Contamination of the air by tobacco smoke. (12 Dec 1998) |