Asbestos insulation


Asbestos insulation was the biggest source of asbestos exposure for workers throughout the 1900s. It was used in homes, buildings, ships, cars and manufacturing facilities, just to name a few. If insulation was needed, asbestos was used. For much of the 20th century, insulators were referred to as “asbestos workers” because they handled the material so frequently.
Insulation helps conserve energy, lower sound volume, reduce electrical conductivity, and retain hot and cold temperatures. Asbestos, a fire-resistant mineral that was cheap, durable and a poor conductor of electricity, naturally became a key ingredient of these products.

Some of the first uses of asbestos insulation occurred in the latter half of the 1800s where hot-temperature pipes were a concern. Heat insulation containing asbestos was used for the first time in 1866. A few years later in 1870, the mineral was mixed with cement for boiler coverings. By 1874, asbestos insulation products reached commercial production and were sold on a mass scale.

Bans on this type of insulation didn’t occur until the 1970s. In 1991, the U.S. Environmental Protection Agency (EPA) lifted the ban and made it possible for companies to produce these products as long as they contained less than 1 percent asbestos.

One of the biggest manufacturers of these insulation products was Johns Manville. It was also one of the first companies to publicly advertise that asbestos was a beneficial addition to their products during the early 1900s. From the early 1900s to the 1970s, Johns Manville made significant use of the mineral in a variety of its products.
Types of Insulation

Insulation can be grouped into five main categories: attic, pipe, block, wall and spray-applied. Asbestos was incorporated into all of these types before regulations limited its use in products during the late 1970s.


Attic insulation was one of the primary sources for exposure. Zonolite insulation is one of the most recognized asbestos insulation brands and it was primarily used in attics. Heating, ventilation and air conditioning systems located in attics were often insulated using the mineral. Loose-fill attic insulation presented some of the greatest risks for exposure.


Pipe insulation or pipe covering remains one of the most hazardous asbestos products found in homes and buildings. It was often used to control the temperature of hot pipes, especially in shipbuilding. Pipe covering that is found today is usually old, crumbly and therefore very hazardous. Air Cell pipe insulation was a very common type.


Block insulation was applied to concrete blocks of homes, apartments and other buildings as a way to maintain hot and cold temperatures. It was an easy way to provide additional protection from the weather outside.


Wall insulation is the most important form for controlling the temperature inside a home or building. It was inserted directly behind drywall between the studs. This type usually came in a roll and sometimes required cutting so it could fit, increasing the risk for asbestos exposure.


Spray-applied insulation is a simple, inexpensive way to provide thermal protection in attics, walls, ceilings and other spaces. Unfortunately asbestos was a common additive in these products before regulations limited its use. In 1990, NESHAP prohibited the spray-on application of materials containing more than 1 percent asbestos unless it was encapsulated with a bituminous or resinous binder during spraying.

Valve Insulation Jackets

This product was used for boilers, flanges, pipe work, expansion joints and other temperature-sensitive equipment. They were typically used in industrial or commercial settings, although the energy efficiency they provided made them a useful tool in residential and public facilities, too. In good condition the jackets posed little risk. But as the jackets wore down through everyday wear and tear, asbestos fibers became airborne. Valve insulation jackets with asbestos are no longer made, but the dangers still exist in older buildings where they remain.
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