A highly toxic material called asbestos is known to cause lung cancer, mesothelioma, and asbestosis, but for decades in the 20th century before its dangers were made public, it was used extensively in construction and in the automobile and shipbuilding industries. It added heat resistance and strength to the materials with which it was combined, and since it could be obtained cheaply, the mineral was used in everything from protective clothing to brake lining.
Asbestos was a regular component in patching plaster that was frequently used to patch any cracks, gaps, and holes in walls, ceilings, and wall joints. People who live or work in houses or commercial buildings where patching plaster has been used are at some risk of exposure to asbestos, but only if that material gets disturbed. But those at a higher risk are the people who worked in an industrial environment where asbestos products like patching plaster were manufactured or other asbestos products were used in construction or manufacturing processes.
The dangers of asbestos were suspected as early as the 1930s, but companies did not protect their workers nor warn them of the dangers. Most people who were exposed did not find about the dangers until it was too late. Unfortunately, since asbestos-related diseases like mesothelioma have decades-long latency periods, many who were exposed are only now realizing the dire health consequences of working with asbestos.