Asbestos is a poor conductor of electricity and is known for its excellent heat-, fire-, and chemical-resistant properties. It was widely used to insulate pipes and boilers in steam locomotives, line tanks and ovens in refineries, used in brakes and clutches of automobiles, as thermal insulation in buildings, and in construction materials such as shingles, ceiling and floor tiles, siding, stucco, and plaster. Exposure to asbestos was common in aluminum plants, steel mills, power plants, oil refineries, chemical plants, and naval shipyards. Asbestos was widely used in the United States from 1950ís until 1972 when Federal exposure limits were imposed. The photograph shows silky fibers of tremolite asbestos; Photograph courtesy of: Aram Dulyan.