Asbestos is a naturally occurring silicate mineral that was mined around the world for centuries. It has six types: chrysotile, crocidolite, amosite, anthophyllite, tremolite and actinolite. They differ in their color, texture and location. Chrysotile, also known as white asbestos, is the most common type and accounts for about 95% of the asbestos used in the UK. Crocidolite, also known as blue asbestos, is the second most common type and the most dangerous, as its fibers are thin and sharp and can penetrate deep into the lungs. Amosite, also known as brown asbestos, is the third most common type and often used in insulation boards and pipe lagging. The other types are less common and usually found in rocks and soils.

Asbestos was first recognized as a health hazard in the early 20th century, when doctors noticed that miners and factory workers exposed to asbestos dust suffered from lung scarring and cancer. However, it was not until the 1960s and 1970s that the UK government began to regulate and limit the use of asbestos in building materials. By the 1980s and 1990s, the dangers of asbestos were widely known, and the UK banned its importation, manufacture, and supply in 1999.