Asbestos

The deleterious health effects of asbestos have become apparent only since the end of World War II. Prior to that time, very few measurements had been made of the concentration of asbestos in the air around workplaces and other settings in which asbestos was used. In addition, the connection between the mineral and its health effects was difficult to recognize since those effects typically do not manifest themselves for 20 years or more after exposure.

Today scientists know that a rather narrow range of asbestos fiber lengths (less than two microns and five to 100 microns in length) can cause a range of respiratory problems, especially asbestosis, lung cancer, and mesothelioma. These problems begin when asbestos fibers enter the respiratory system and become lodged in the interstitial areas—the areas between the alveoli—in the lungs. As the fibers continue to accumulate in the lungs, they can cause the development of fibrous scar tissue that reduces the flow of air through the respiratory system.

Symptoms that gradually develop include coughing and shortness of breath, weight loss, and anorexia. Other respiratory conditions, such as pneumonia and bronchitis, become more common and more difficult to cure. Eventually the fibers may initiate other anatomical and physiological changes, such as the development of tumors and carcinomas. Individuals most at risk for asbestos-related problems are those continually exposed to the mineral fibers. This includes those who work in asbestos mining and processing as well as those who use the product in some other manufacturing line, as in the production of brake linings.

Over the past two decades, intense efforts have been made to remove asbestos-based materials from buildings where they are especially likely to pose health risks, as in school buildings and public auditoriums. Recent critics of asbestos removal maintain that if not done properly, asbestos removal spreads more asbestos fibers into the air than it actually removes. Also, there has not been a satisfactory substitute found for the asbestos materials being removed.