Asbestos is a naturally occurring mineral that was widely used in the construction industry during the 20th century. Its resistance to heat, fire and chemicals made it a popular material for the insulation of buildings, pipes and machinery. However, scientists later discovered that asbestos is highly carcinogenic and can cause a variety of serious health problems including lung cancer, mesothelioma and asbestosis. Asbestos is now banned in many countries, but it can still be found in many older buildings.