Asbestos is a soft, threadlike mineral fiber that was commonly used commercially due to its beneficial properties. However, inhaling asbestos fibers can lead to serious lung diseases like asbestosis, bronchogenic cancer, and mesothelioma. These diseases may not appear for many years after exposure and can be fatal. While asbestos was widely used in insulation and other building materials, many countries have now banned its use, especially in schools, due to the significant health risks to workers and occupants.