Manufacturing facilities are among the industries in the United States that are responsible for emissions of air pollution. These include factories and other operations, large and small, that produce goods that will be used by individual consumers (e.g., automobiles, appliances, clothing, food). They also include facilities that make intermediate goods that are destined for other manufacturing plants, such as building materials and parts to be used in the creation of end-use items. Because there is such a wide variety of manufacturing facilities, the list of air pollutants they emit is a long one. Many, if not most, of the pollutants the federal Clean Air Act has identified for regulation are emitted by some type of manufacturing facility. Likewise, the controls used by these sources to reduce or eliminate air pollution vary widely, depending on the sizes and types of plants and the substances they emit.