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Asbestos Basics


What is Asbestos?

Asbestos is the generic term for a group of naturally occurring highly toxic fibrous silicate minerals with high tensile strength, flexibility, and resistance to thermal, chemical, and electrical conditions.

Chemically, asbestos minerals contain silicon and oxygen atoms in their molecular structure. Asbestos is also resistant to heat and corrosion.

Asbestos fibers are 5 micrometers or longer with a length-to-diameter ratio of at least 3 to 1.

Asbestos includes the mineral fibers chrysotile, amosite, crocidolite, tremolite, anthophyllite, actinolite and any asbestos-containing material (ACM) or presumed asbestos-containing material (PACM) that have been chemically treated or altered.

Asbestos may also be “friable” or “non-friable”:

  • Friable asbestos is material containing more than 1% asbestos by weight or area that is crumbly, dusty or powdery. It can be crumbled, pulverized or reduced to powder form using the hands. Most asbestos-containing material is friable. Examples include: sprayed coatings or insulation, lagging, loose asbestos, or asbestos in its raw state.
  • Non-friable asbestos is material containing more than 1% asbestos which is held within another material and cannot be crumbled, pulverized, or reduced to powder using the hands.

According to the Environmental Protection Agency (EPA), there are two major groups of asbestos:

Dangerous Asbestos Types - LCAV
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  • Serpentine: These fibers can be woven together and are flexible and long.
    • Chrysotile, or white asbestos, is the primary type of serpentine and is used in manufacturing processes. It is in over 95% of asbestos-containing materials and used in about 90% of all commercial processes.
    • Amosite, also called brown asbestos, is generally used in spray coatings, heat insulation, and cement products.
    • Crocidolite, or blue asbestos, is not used much, but found in spray coatings on structure steelwork for fire protection and heat or noise insulation.
  • Amphiobole:These fibers are brittle, rod- or needle-shaped, straight and relatively stiff. These characteristics make this group, composed of actinolite, anthophyllite, and tremolite relatively useless for commercial processes.

When handled, asbestos can separate into microscopic-size particles that remain in the air and are easily inhaled. Persons occupationally exposed to asbestos have developed several types of life-threatening diseases, including asbestosis, lung cancer and mesothelioma. Although the use of asbestos and asbestos products has dramatically decreased in recent years, they are still found in many residential and commercial settings and continue to pose a health risk to workers and others. Check out this comprehensive list of asbestos-containing-products.

Historical Perspectives

Asbestos has been used since the late 1800s in commercial applications and the use increased greatly throughout World War II.

Before experts knew that the inhalation of asbestos fibers caused several deadly diseases- including asbestosis, a progressive and often fatal lung disease, and lung and other cancers- asbestos was used in a large number of building materials and other products because of its strength, flame resistance, and insulating properties. Asbestos was used in asbestos-cement pipe and sheeting, floor and roofing felts, dry wall, floor tiles, spray on ceiling coatings, and packing materials.

Always presume building materials may contain asbestos. The U.S. has not banned asbestos entirely in all its forms, so employers must take caution when buildings, especially those built before 1980, are renovated or torn down. A commercial building or residence may still contain asbestos. Remember, when the asbestos-containing materials themselves are disturbed, fibers may be released into the air. The fibers are so small that workers cannot see it with the naked eye. The fact you can inhale these fibers without knowing it makes asbestos an even more dangerous hazard.

Asbestos may also still be found in some taping compounds, asbestos cement, pipes, and floor tiles. Vinyl asbestos floor tiles may be as much as 15% to 20% asbestos, which is released when old flooring is removed.

Only specially trained asbestos workers may remove asbestos. Significant exposure to asbestos can cause breathing problems, lung cancer, and cancer of the lung lining many years after exposure.

Where Asbestos is Used

Asbestos in Demolition and Renovation – WorkSafeBC
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Asbestos was used in military ships, vehicles and aircraft until the 1970s and many thousands of those who served in the military were exposed.

Because asbestos is strong and resistant to heat, it has been used in many different types of products, such as insulation for pipes (steam lines for example), dry wall, ceiling and floor tiles, building materials, cement, and in vehicle brakes and clutches.

Commercial building and residential homes built prior to 1980 still contain asbestos, but exposure is not serious unless the asbestos has been disturbed in some way. If disturbed, asbestos fibers can go airborne and be inhaled.

In the construction industry, asbestos was used in more than 3,000 building products. Some materials are presumed to contain asbestos if installed before 1981. Examples of these materials, as well as other presumed asbestos-containing materials are:

  • boiler, pipe, furnace, and water heater insulation,
  • ceiling and wall texture “popcorn” and “orange peel,”
  • taping mud compound, skim coat,
  • acoustical tiles, sprayed-on insulation and fire proofing,
  • vinyl floor tile, sheet vinyl and linoleum,
  • mastics and glues, cement asbestos board,
  • niccolite paper under wood roofing shingles, built-up roofing, roof felt and patch, paints, including silver roof paint, stucco and texture,
  • vermiculite and blown-in building insulation, door and cover gaskets, window putty,
  • insulation boards behind and under wood stoves, insulation within older dishwashers and ranges,
  • older electrical wire, black tar coating on the underside of sinks, stove top pads, and ironing board covers

A common misconception is all asbestos-containing products are banned for use in the U.S. Actually, the only products banned from use are the following:

  • fireproofing and insulating products,
  • spray-applied surfacing materials,
  • thermal system insulation (TSI),
  • wet-applied and preformed pipe insulation,
  • pre-formed block insulation for boilers and hot water tanks,
  • corrugated paper, rollboard, commercial paper, specialty paper, flooring felt, and
  • any new use of asbestos.

Did You Know?

Dangerous insulation.
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Here’s some interesting information obtained from Sokolove Law and highlights why asbestos in the U.S. is considered the Silent Killer:

  • Between 1979 and 2001, there were 230,000 asbestos related deaths.
  • Despite being a known carcinogen, asbestos is not banned.
  • Asbestos consumption increased 35% between 2010 and 2011; roofing products account for 72% of consumption.
  • One in every three deaths from occupational cancer is caused by asbestos.
  • Several thousand deaths annually are attributed to asbestos exposure in the home.
  • On average, there are 30 asbestos related deaths a day.
  • Asbestos containing vermiculate insulation product called Zonolite is believed to be in 35 million homes, schools, and office buildings.
  • Asbestos snow was used in the poppy scene in the Wizard of Oz.
Asbestos - WorkSafeBC
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Health Effects of Asbestos
Health Effects of Asbestos
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Scars in Lung Tissue
Scars in lung Tissue - CDC
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Scars in Lung Tissue
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Health Hazards of Asbestos

Exposure to asbestos increases your risk of developing lung disease as fibers become embedded and accumulate in lung tissue over time. There is no known safe level of exposure to asbestos, so contact with any amount of asbestos should be avoided. Disease symptoms may take several years to develop following exposure.


Asbestosis is a serious, progressive, long-term non-cancer disease of the lungs. It is caused by inhaling asbestos fibers that lodge in the alveoli and cause the tissues to scar. The scarring makes it hard for oxygen to get into the blood.

Symptoms of asbestosis include shortness of breath and a dry, crackling sound in the lungs while inhaling. There is no effective treatment for asbestosis.

Lung Cancer

Lung cancer causes the largest number of deaths in the U.S. related to asbestos exposure. People who work in the mining, milling, manufacturing of asbestos, and those who use asbestos and its products are more likely to develop lung cancer than the general population.

The most common symptoms of lung cancer are coughing and a change in breathing. Other symptoms include shortness of breath, persistent chest pains, hoarseness, and anemia.


Epidemiologic evidence has increasingly shown that all asbestos fiber types, including the most commonly used form of asbestos, chrysotile, causes mesothelioma in humans.

Mesothelioma is a rare form of cancer due to asbestos fibers lodging in the thin lining of the lungs causing tumors to grow in the lung, chest, abdomen, and heart. This disease may not show up until many years after asbestos exposure.

It is important to know the following things about exposure to asbestos:

  • Airborne levels of asbestos are never to exceed legal worker exposure limits.
  • There is no "safe" level of asbestos exposure for any type of asbestos fiber.
  • Asbestos exposures as short in duration as a few days have caused mesothelioma in humans.
  • Every occupational exposure to asbestos contributes to the risk of getting an asbestos related disease.


Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. All buildings and homes, especially those built before _____ may contain asbestos-containing materials.

2. Which term below describes material that contains more than 1% asbestos and is crumbly, dusty or powdery?

3. Which of the following is in over 95% of asbestos-containing materials and used in about 90% of all commercial processes?

4. Why has asbestos been used in many different types of products?

5. Which of the following is a disease of the lungs caused by inhaling asbestos fibers that lodge in the alveoli and cause the tissues to scar?

Have a great day!

Important! You will receive an "error" message unless all questions are answered.