Furnaces and Asbestos Exposure

Hot air furnaces are critical parts of the heating, ventilation and air-conditioning (HVAC) systems for most buildings. Furnaces come in different shapes, sizes and configurations and are found in homes, schools and factories.

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Furnaces and Asbestos Exposure

Furnaces replaced radiant fireplaces in American buildings in the mid-1800s. Since then, there’ve been significant advances in furnace technology including different heat-generating fuels. There’s also been a change in furnace construction.

Before the mid-1980s, every furnace in the nation contained deadly asbestos materials.

Furnaces consisted of components like firebox refractories, boilers, ducts, registers, flues and chimney. Stoves and kilns were also considered furnaces. So were giant steel smelters and industrial incinerators.

No matter what part or type of furnace, asbestos-containing materials (ACM) were standard in furnace construction and installation.

Furnaces contained asbestos products mainly because of the material’s ability to withstand extreme heat. Some furnaces reach temperatures over 3,000 degrees, but that did not affect asbestos materials. This material seemed a miracle to the furnace industry.

Not only was asbestos non-flammable, it was also non-corrosive, electrically non-conductive and chemically inert.

Asbestos didn’t react with wood, coal, oil, or gas fossil fuels. And to seem even better, asbestos was easy to work with, stable when added to other materials and readily available. Plus, asbestos was cheap.

Furnace Components with Asbestos-Containing Materials

Asbestos was everywhere in twentieth-century furnaces. Its most important use was in isolating hot fireboxes, burners, and boilers from combustible materials and surfaces.

Because asbestos was thermally inert, it didn’t transfer heat which could cause secondary fires to building components.

Asbestos was an insulator and sealant commonly found on:

  • Furnace linings, combustion chambers and firebricks
  • Heat shields where furnaces mounted to floors
  • Ductwork and delivery pipes
  • Door and inspection hatch gaskets
  • Vibration dampers and heat isolators
  • Joint sealant and duct wrapping tape
  • Furnace cement and joint compound
  • Forced-air heat blowers

Chrysotile asbestos was the most common mineral fiber form used in furnaces and their system components. Over 90 percent of asbestos-containing furnace materials used chrysotile or “white” asbestos.

Chrysotile is called a serpentine asbestos fiber due to its soft, serpent-like shape when viewed under a microscope. In raw form, chrysotile isn’t as dangerous as its deadly cousin, amphibole asbestos, that has a sharp, crystalline form.

Many other products used chrysotile asbestos with little harm once the material was installed and sealed. Asbestos-containing products like paint, flooring and drywall stayed inert as long as the content wasn’t disturbed. But, furnace operation was a different game.

The very nature of running a furnace put chrysotile asbestos in a constant state of disturbance. Substantial hot and cold heat fluctuations caused significant expansion and contraction rates in furnace systems.

Chrysotile asbestos products in sealants, gaskets, and duct wrap quickly dried out and crumbled. This quality is called being friable.  Asbestos dust regularly filled the ambient air with tiny asbestos particles. The entire furnace system steadily supplied brittle asbestos fibers into the environment.

Risk of Asbestos Exposure from Furnaces

Everyone near a furnace containing ACM was at risk of airborne asbestos exposure. It was impossible to escape when in the environment where asbestos furnaces existed.

These are those at the highest risk of exposure to furnace asbestos:

  • Workers in manufacturing areas for asbestos components.
  • Installers dealing with putting asbestos-containing furnace systems in place.
  • Operators who looked after furnaces and continuously worked around systems.
  • Repair and service technicians going from furnace to furnace.
  • Building occupants who inhaled asbestos fibers in their environment.

Furnace Asbestos and Mesothelioma

Every worker and building occupant exposed to airborne asbestos caused by furnace operation was at risk of developing a fatal lung disease called mesothelioma.

When chrysotile or amphibole asbestos fibers were inhaled, they could get stuck to the linings of the lungs, abdomen, heart, or testicles. The body couldn’t expel or break down these asbestos fibers.

Asbestos particles stayed in the body forever and caused scar tissue buildup. This exposure eventually led to mesothelioma.

Compensation for Mesothelioma Victims

Although there is no known cure for advanced mesothelioma, victims can receive compensation for personal injury damages, lost income, and medical expenses.

Families of asbestos victims can act on their behalf to file mesothelioma claims to access compensation. They can also file lawsuits in wrongful death cases.

Mesothelioma Support Team
Stephanie KiddWritten by:


Stephanie Kidd grew up in a family of civil servants, blue-collar workers, and medical caregivers. Upon graduating Summa Cum Laude from Stetson University, she began her career specializing in worker safety regulations and communications. Now, a proud member of the American Medical Writers Association (AMWA) and Editor-in-Chief of the Mesothelioma Justice Network, Stephanie serves as a voice for mesothelioma victims and their families.

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