Asbestos is a mineral mined from the ground. Asbestos is the name for a group of natural minerals that separate into strong, very fine fibers. A typical asbestos fiber is 1,200 times smaller than a strand of human hair. The fibers are heat-resistant and extremely durable. These qualities once made asbestos very useful in construction and industry. Asbestos fibers were generally mixed with a material that bound them together so they easily could be used in many different products. (The photo above is chrysotile asbestos. The photo below is chrysotile asbestos fiber enlarged 150 times.)

Of the many varieties of asbestos, the three most common are chrysotile, amosite and crocidolite. Chrysotile fibers are pliable, cylindrical and often arranged in a bundle. Amosite and crocidolite fibers resemble tiny needles. Most of the commercial products containing asbestos used chrysotile fibers.

Asbestos became a popular commercial product because it is strong, won’t burn, resists corrosion and insulates well. Its commercial use in the United States began in the early 1900s, when it was used as insulation in steam engines. Since then, asbestos has been used to create about 3,000 products for insulation, fireproofing and purposes.

Between 1900 and 1980, some 30 million tons of asbestos were put in place. Since the 1970s, asbestos use has declined significantly. Yet even now, U.S. companies mine and process about 200,000 tons of asbestos every year for use in hundreds of different products.

The asbestos fiber’s shape, durability and strength have made it a popular construction ingredient. But unfortunately, these same properties also make the fiber a hazard to humans. The fine fibers can be inhaled or ingested and lodge in the lungs or elsewhere, where they then can cause disease.

Although most construction products sold today in the United States do not contain asbestos, exposure can still occur, particularly from asbestos products that remain in buildings. Anyone who owns an older building should take care that the original asbestos is not released into the building environment, creating a new health hazard. For example, that can still happen today when new cables are installed to a beam fireproofed with asbestos; when vinyl asbestos tile floor is removed by sanding; and when asbestos-insulated pipes are repaired.

Whether or not an asbestos-containing product releases asbestos depends on several factors, such as location and the degree of friability. According to the EPA, friable means that the product can be crumbled with hand pressure and therefore may be more likely to emit fibers when disturbed. Generally considered friable are the fibrous or fluffy spray-applied asbestos materials used in many buildings for fireproofing, insulating or decorative purposes. Some materials such as vinyl floor tiles are less likely to emit airborne fibers unless subjected to disturbances such as sanding or cutting.