Frequent or prolonged exposure to asbestos may lead to the formation of pleural plaques within a period of 20 to 40 years. The asbestos fibers inhaled during the exposure may remain within the lining of the lungs, subsequently irritating the tissues. Thus, the thickening of the pleura or diaphragm is more likely to occur during the decades following the contact. Moreover, it has been demonstrated that the risk of developing pleural plaques after exposure to asbestos depends to a great extent on the quantity inhaled, as well as on the duration of the exposure. However, pleural plaques can also appear in conditions such as pleural tuberculosis or thoracic trauma when the healing process is complete, but their characteristics are slightly different from the asbestos-related ones.