Asbestos is a group of fibrous minerals that occur naturally. When humans are exposed to asbestos, it can cause various diseases. The principal occupational diseases associated with exposure to asbestos are as follows: Asbestosis is a chronic non-cancerous disease of the respiratory organs. Inhalation of asbestos fibers results in the destruction of lung tissues, which leads to their scarring. Lung cancer is another disease associated with asbestos exposure. Individuals engaged in the mining, grinding, production, and use of asbestos and its products have a significantly higher incidence of lung cancer than the general population. Mesothelioma is a rare form of cancer that most commonly occurs in the mucous membranes of the lungs, some tissues of the chest, abdomen, and (rarely) the heart. The most dangerous form of asbestos exposure is the inhalation of microscopic particles released during the processing, manufacturing, handling, and repair of asbestos-containing products. To prevent the harmful effects of asbestos, it is essential that production facilities have fume hoods and effective ventilation, that workers wear protective clothing and respirators, and that they use other personal protective equipment. * * * An asbestos clause in a construction contract affords protection to the contractor performing work on the customer's premises. It allows the contractor, under certain conditions, to suspend work at a site where asbestos concentration limits have been exceeded and to require the client to ensure that the concentration of asbestos dangerous to health is reduced. Should the concentration level remain unabated for a specified period, the contractor is entitled to withdraw from the contract. At certain levels of asbestos concentration, the customer is obliged to provide the contractor's employees with personal protective equipment (PPE) corresponding to a certain hazard class, depending on the degree of asbestos concentration.