Asbestos is a naturally occurring mineral that was widely used in the construction of buildings throughout the 20th century. It was used for its excellent insulating and fire-resistant properties, as well as for its strength and durability. However, asbestos is a highly dangerous substance that can cause serious health problems, including lung cancer and mesothelioma, if inhaled.

There are six types of asbestos, all of which have been used in building materials:

• Chrysotile (white asbestos)
• Amosite (brown asbestos)
• Crocidolite (blue asbestos)
• Anthophyllite
• Tremolite
• Actinolite

All types of asbestos are hazardous, but the most dangerous are crocidolite and amosite. It's important to note that even if asbestos is not airborne, it can still be harmful if it's damaged or disturbed, releasing microscopic fibres into the air that can be inhaled. This is why an asbestos survey is essential before any work is carried out on a building that could disturb asbestos.