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U.S.-Canada Air Quality Agreement

In 1991, the U.S. and Canada entered into an agreement to address transboundary air pollution, whereby pollutants released at one location can travel long distances, affecting air quality at their sources, as well as many miles away. The 1991 Agreement led to reductions in acid rain in the 1990s, and was expanded in 2000 to reduce transboundary smog emissions under the Ozone Annex.

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