Asbestos is a naturally occurring mineral fiber found in rocks and soil. It was once widely used in building materials and products to strengthen them and provide heat insulation and fire resistance. Asbestos can still be found in some products today, where alternative materials do not work. When intact and undisturbed, asbestos-containing materials generally do not pose a health risk. Damaged asbestos-containing materials may pose a health risk if fibers are released into the air and inhaled into the lungs.