Asbestos (pronounced: or ) is a term used to refer to six naturally occurring silicate minerals. All are composed of long and thin fibrous crystals, each fibre being composed of many microscopic 'fibrils' that can be released into the atmosphere by abrasion and other processes. Asbestos is an excellent electrical insulator and is highly heat-resistant, so for many years it was used as a building material. However, it is now a well-known health and safety hazard and the use of asbestos as a building material is illegal in many countries. Inhalation of asbestos fibres can lead to various serious lung conditions, including asbestosis and cancer.Archaeological studies have found evidence of asbestos being used as far back as the Stone Age to strengthen ceramic pots, but large-scale mining began at the end of the 19th century when manufacturers and builders began using asbestos for its desirable physical properties.
Asbestos was widely used during the 20th century until the 1970s, when public recognition of the health hazards of asbestos dust led to its prohibition in mainstream construction and fireproofing in most countries. Despite this, and in part because the consequences of exposure can take decades to arise, at least 100,000 people are thought to die each year from diseases related to asbestos exposure.Despite the severity of asbestos-related diseases, the material has been widely used all over the world, and most buildings constructed before the 1980s are thought to contain asbestos. Many developing countries still support the use of asbestos as a building material, and mining of asbestos is ongoing, with top producer Russia having produced about one million tonnes in 2015.