Not all workers exposed to asbestos will develop diseases related to their exposure. The risk of developing asbestos-related diseases varies with the type of industry in which the exposure occurred and with the extent of the exposure. Asbestos that is bonded into finished products, such as walls and tiles, poses no risk to health as long as it is not damaged or disturbed (for example, by sawing or drilling) in such a way as to release fibers into the air. When asbestos fibers are set free and inhaled, however, exposed individuals are at risk of developing an asbestos-related disease.
In addition, different types of asbestos fibers may be associated with different health risks. For example, results of several studies suggest that amphibole forms of asbestos may be more harmful than chrysotile, particularly for mesothelioma. Even so, no fiber type can be considered harmless, and people working with asbestos should always take proper safety precautions to limit exposure.
Many studies have shown that the combination of smoking and asbestos exposure is particularly hazardous. Smokers who are also exposed to this material have a greatly increased risk of lung cancer. However, smoking combined with asbestos exposure does not appear to increase the risk of mesothelioma.
There is evidence that quitting smoking will reduce the risk of lung cancer among asbestos-exposed workers. People who were exposed to asbestos on the job at any time during their life (or who suspect they may have been exposed) should not smoke. If they smoke, they should stop.