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How does air pollution cause acid rain?

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Dense smog and orange haze blanket the skyline of Mexico City at sunset, with buildings in the Polanco neighborhood partially obscured by air pollution. — air pollution Pollution darkening the skies over Mexico City.

Air pollution causes acid rain when sulfur dioxide (SO₂) and nitrogen oxides (NO_x) are released into the atmosphere, primarily from burning fossil fuels. These pollutants travel long distances and react with water, oxygen, and other chemicals to form sulfuric and nitric acids. These acids then mix with cloud moisture, lowering the pH of precipitation, which falls to Earth as acid rain. While natural sources like volcanic eruptions can contribute, human activities are the main cause of acid rain. Acid rain can harm ecosystems by depleting soil nutrients and releasing toxic aluminum, and it also corrodes buildings and monuments.123