Asbestos is a naturally occurring mineral that was widely used in construction and manufacturing for much of the 20th century. It was valued for its heat-resistant and insulating properties, but it was only in the last few decades that the dangers of asbestos exposure have become widely known. Asbestos can cause a range of serious health issues, including lung cancer, mesothelioma and asbestosis. As a result, it is now banned from use in many countries around the world.