Nearly everyone is exposed to asbestos at some point, although the vast majority of people do not become ill as a result. People who become ill from asbestos are usually those who are exposed to it on a regular basis, most often in a job where they work directly with the material or where substantial amounts of it are/were present in the environment.

Since the early 1940s, millions of American workers have been exposed to asbestos. Health hazards from asbestos dust have been recognized in workers exposed in shipbuilding trades, asbestos mining and milling, manufacturing of asbestos textiles and other asbestos products, insulation work in the construction and building trades, brake repair, and a variety of other trades. Demolition workers, drywall removers, and firefighters also may be exposed to asbestos dust. As a result of Government regulations and improved work practices, today's workers (those without previous exposure) are likely to face smaller risks than did those in the past.

Although it is known that the risk to workers increases with heavier exposure and longer exposure time, investigators have found asbestos-related diseases in individuals who had only brief exposures. Generally, workers who develop asbestos-related diseases show no signs of illness for a long time after their first exposure. It can take from 10 to 40 years for symptoms of an asbestos-related condition to appear.

There is some evidence that family members of workers heavily exposed to asbestos face an increased risk of developing mesothelioma. This risk is thought to result from exposure to asbestos dust brought into the home on the shoes, clothing, skin, and hair of workers. This type of exposure is called paraoccupational exposure. To decrease chances of such exposure, asbestos workers who are directly or indirectly exposed to asbestos are usually required to shower and change their clothing before leaving the workplace.

How Great is the Risk?

Not all workers exposed to asbestos will develop diseases from their exposure. In fact, many will experience no ill effects.

Asbestos that is bonded into finished products such as walls, tiles, and pipes 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 particles are set free and inhaled, however, exposed individuals are at risk of developing an asbestos-related disease. Once these fibers work their way into body tissues, they may stay there indefinitely.

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. In addition, different types of asbestos fibers may be associated with different health risks. There are many varieties of asbestos, and several studies suggest that certain forms of asbestos are more likely than others to cause lung cancer, asbestosis, and, in particular, mesothelioma. Even so, no fiber type can be considered harmless, and people working with asbestos should always take proper safety precautions.

Today, the U.S. Occupational Safety and Health Administration (OSHA) has three standards to protect workers from exposure to asbestos in the workplace: one regulates construction work, including alteration, repair, renovation, and demolition of structures containing asbestos; another covers asbestos exposure during work in shipyards; and the third applies to asbestos exposure in general industry, such as exposure during brake and clutch repair, custodial work, and manufacture of asbestos-containing products.

Moreover, the Environmental Protection Agency's "Worker Protection Rule" extends standards implemented by OSHA to state and local employees who perform asbestos work and who are not covered by the OSHA Asbestos Standards, or by a state OSHA plan. The Worker Protection Rule parallels OSHA requirements and covers medical examinations, air monitoring and reporting, protective equipment, work practices, and record keeping. In addition, many state and local agencies have more stringent standards than those required by the Federal government.

How Does Smoking Affect the Risk?

Many studies have shown that the combination of smoking and asbestos exposure is particularly hazardous. Smokers who are exposed to asbestos 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.