Lagging adhesive is used to seal ducts and ventilation to prevent temperature-treated air from leaking out. For many years this lagging adhesive was made from asbestos because it was strong and durable, resistant to heat and fire, and a great insulating material. Its inexpensiveness and availability added to the reasons that it was so commonly used.
In the 1970s there were a number of people who had worked as HVAC technicians or other heat system workers who were diagnosed with illnesses that resulted from their exposure to asbestos. A group of these people filed lawsuits against the companies that manufactured these materials and demanded that production be stopped. Despite this, many manufacturers continued to use the lagging adhesive containing asbestos.
As time goes on, the asbestos found in lagging adhesive can break down and millions of tiny particles of asbestos can get into the air where anyone in the area can inhale them. Once in the body they cause the tissue to become inflamed and can ultimately result in mesothelioma.