Compounds formed when fossil fuels are burned combine with water in the atmosphere to form acids which fall to the earth's surface as acid rain.
Oxides of nitrogen, which form when gasoline is combusted at a high temperature, are one cause of acid rain. Nitrogen oxides react with water to form HNO2 and HNO3, nitrous and nitric acids.
Sulfur dioxide that comes from burning coal and diesel reacts with water to produce sulfurous and sulfuric acids, H2SO3 and H2SO4. Sulfur and nitrogen emisisons are the top sources of acid precipitation.
Carbon dioxide from fossil fuel emissions combines with water both in the atmosphere and in the ocean to form carbonic acid.
Acid precipitation causes erosion of limestone and marble statues and buildings and corrodes steel structures. It also has an adverse affect on living things. Forests are damaged by acid rain that changes the pH of the soil. Acidic surface water is a threat to fish and other aquatic organisms. Coral, which has a calcium carbonate skeleton, is damaged by acidification of the ocean.