How Much Pollution Comes From Vehicles?

Unlike other pollutants in the air around Roanoke, ozone is not emitted into the air directly. Rather, it is formed when there is sunlight by chemical reactions between nitrogen oxides and volatile organic compounds. Usually automobiles emit about 1/3 of these ozone-forming pollutants, and the other 2/3 are emitted by smaller sources to include lawn and garden tools, paints, boats, and various industries.