Because of its insulating and fire resistant properties, asbestos was used widely in the 20th century in the manufacturing, construction, and shipbuilding industries. Asbestos was contained in thousands of products over several decades, including cement board building materials like permaboard.
Permaboard that contained asbestos was used to make both indoor and outdoor ceilings and walls. It was also used anywhere that heat protection and insulation was needed like around furnaces, wood stoves, and boilers. Permaboard made with asbestos, though containing cement and other ingredients, often consisted of up to 80% asbestos.
It is always dangerous when asbestos is present in the home or workplace, but the permaboard is safe as long as it remains in good condition. Asbestos only becomes dangerous when it becomes disturbed or damaged, causing the fibers to get airborne where they can be inhaled. The people most at risk are those who worked in industrial environments where asbestos was used to manufacture things like permaboard or in industries like shipbuilding or construction.