Asbestos: A natural material made up of tiny fibers which can lodge in the lungs and lead to cancer or scarring of the lungs. The cancer may be lung cancer or ( mesothelioma ), which is a cancer of the lining of the lungs or other internal organs. The scarring of the lungs is termed asbestosis . Exposure to asbestos usually occurs by breathing contaminated air in workplaces that make or use asbestos or in the air of buildings containing asbestos that are being torn down or renovated.

Asbestosis: A condition featuring scarring of the lungs caused by inhaled asbestos fibers. Asbestosis is irreversible. It tends to lead to COPD (chronic obstructive pulmonary disease), a progressive disorder that can be disabling or fatal.