FIGURE 46.4 Natural sources of air pollution. There are many natural sources of air pollution, including volcanoes, lightning strikes, forest fires, and plants. (a) A forest fire in Ojai, California, produces air pollution. (b) The Great Smoky Mountains were named for the natural air pollutants that reduce visibility and give the landscape a smoky appearance.
(a: R. Krubner/ClassicStock/The Image Works; b: Marvin Dembinsky Photo Associates/Alamy)