Asbestos is a naturally occurring mineral that was widely used in building materials throughout the 20th century. It was prized for its resistance to heat, fire, and chemicals, and was often used as insulation, fireproofing, and ceiling tiles.

However, it was later discovered that asbestos can cause serious health problems when its fibers are inhaled. Asbestos fibers can become airborne during work on asbestos-containing materials, and when inhaled, they can become lodged in the lungs or digestive system, leading to diseases such as mesothelioma, lung cancer, and asbestosis.

For this reason, the use of asbestos in building materials has been banned in the UK since 1999. However, many buildings constructed before this time still contain asbestos, and it's vital to identify and manage any ACMs present during refurbishment or demolition work.