Heat Guards Before the 1980s, products made of asbestos were often used in the construction industry, in the development of large buildings and in applications for building renovation. This mineral is extremely fire resistant. During this period, heat guards were made using asbestos combined with other organic materials. The purpose of these guards was to insulate boilers, piping, furnaces, and any other parts that faced exposure to heat. While the asbestos used in the heat guards made an efficient and tough protector against heat and fire, it also exposed those who lived or worked near these heat guards to serious health issues. Finally, in the 1970s the public began to know about the dangers associated with the use of asbestos. Unfortunately, before the dangers were widely publicized, there were thousands of workers and people living in the homes containing heat guards who had been exposed to asbestos. These heat guards were installed in too many pipes and furnaces in too many homes and buildings to count. Those exposed are in danger of developing asbestos-related disease like mesothelioma, the symptoms of which may not appear until 20 to 50 years later after initial exposure.