Acid deposition also affects manufactured materials. It corrodes metals and damages paints and coatings meant to protect items from rust. Although many such items may be restored, maintenance can be expensive. Perhaps the best-known effect of acid deposition is the acidification of surface water. The survey also determined what percentage of these waters were chronically acidic from acid deposition.
Acid deposition affects more than just the pH of surface water.
The influx of nitrogen from acid deposition into surface waters promotes plant growth. When plants die, decomposers consume oxygen, lowering dissolved oxygen levels. Aquatic organisms suffocate, and soon, the water is devoid of life. Acid deposition in the air threatens human health. Lung cancer, asthma, bronchitis, and emphysema are caused and aggravated by air pollutants.