Asbestos was used as a building material from the 1950s until it was banned in 1999.
Asbestos was a wonder-material, and helped to provide fire protection and make materials stronger and hard wearing.
However, asbestos fibres are tiny and indestructible, and once they have been inhaled into the lungs they cannot be removed and cause irreparable damage, leading to lung cancers and eventually death.
About 6500 people die from asbestos related illness each year. This includes around 1000 construction workers.
Construction workers are at high risk of breathing in fibres, as they are likely to find and disturb asbestos during their work.