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Asbestos Exposure - The Complete Guide

What Is Asbestos?

Asbestos is the collective name for a group of minerals made up of long, thin fibers that are invisible to the naked eye. These minerals occur in nature, primarily in underground rock. Many different types of asbestos exist, and each is grouped into one of two categories — serpentine or amphibole — according to the shape of its fibers.


  • Long, flexible fibers that wrap around themselves and form a spiral
  • Accounts for 95 percent of commercial use
  • Chrysotile asbestos is the only member of the serpentine group


  • Straight and brittle fibers shaped like needles or rods.
  • Accounts for 5 percet of commercial use
  • The most common types of asbestos included in the amphibole group are amosite and crocodilite.

Asbestos exists naturally in 6 forms, the most common of which are: chrysotile, amosite, and crocodilite.

A highly durable material, asbestos is resistant to heat, fire, and damage from many chemicals. It works well in insulation because it neither conducts electricity nor corrodes. As a result of its natural properties, asbestos has been used historically in a variety of commercial and industrial products, mainly in the construction and automotive industries.

How Asbestos is Dangerous

Long-term exposure to asbestos fibers causes many serious diseases, including:

  • Lung cancer
  • Mesothelioma, a rare cancer that affects the protective lining of several organs
  • Asbestosis, progressive scar tissue in the lung(s)
  • Pleural plaque, the thickening and hardening of the tissue around the lungs and diaphragm
  • Pleural effusion, fluid build-up in the pleural space (area between the lungs and the chest wall)

Mesothelioma, asbestosis, and lung cancer are the 3 leading causes of death among people who’ve experienced long-term exposure to asbestos. Researchers estimate that 10 million people will die from an asbestos-related diseases by 2030.

Exposure to asbestos in nature is not, however, automatically dangerous. In fact, the normal level of fibers in areas where the mineral occurs naturally is between 0.00001 to 0.0001 fibers per milliliter (fibers/mL). Though experts agree that there is no safe level of asbestos.

The danger caused by exposure increases with the frequency and amount of exposure. If a person comes into contact with asbestos fibers once, their risk of developing an asbestos-related disease is low. People who experience frequent exposure to high amounts of asbestos, however, are more likely to develop an asbestos-related disease.

Scientists consider significant exposure to be 0.125 to 30 fibers/mL. Once again, however, there is no safe amount of asbestos exposure.

The intense use of asbestos in places with poor ventilation increases the risk of causing an asbestos-related disease. Asbestos is friable, a term which means that its fibers break apart and become airborne very easily. Cutting, drilling, repairing, scraping, sanding, or removing structures containing asbestos releases large amounts of the toxic mineral’s fibers into the air. As a result, people who inhabit or work in such structures may ingest or inhale the fibers, which are too small to be seen by the naked eye.

Over time, most of the asbestos fibers that have been inhaled are eventually exhaled. Many of them, however, remain in your body. These fibers eventually reach the ends of the small airways in your lungs and invade the pleura, the protective lining of the lung and chest wall. Asbestos fibers scratch and irritate the lungs, causing scarring and inflammation. Eventually, an asbestos-related disease like mesothelioma may develop.

Symptoms of asbestos-related diseases have a long latency period. The latency period is the time between a patient’s initial exposure to asbestos and their actual diagnosis. As a result of this extended latency period, people who experienced frequent, long-term exposure to asbestos-containing materials between the 1960s and 1980s are commonly diagnosed with lung cancer, mesothelioma, or another respiratory disorder today.

Amphibole vs. Chrysotile

Both amphibole and serpentine (chrysotile) asbestos are carcinogenic. But the amphibole varieties seems to be more likely to cause mesothelioma. This may be due to shape. The rod-like amphibole fibers can penetrate the peripheral lung more easily than curly chrysotile fibers.

Special interests groups have long promoted the idea that chrysotile asbestos poses no health threats. One study, conducted by McGill University in Canada, suggests that chrysotile exposure is basically harmless. The research, however, was funded by the Quebec Asbestos Mining Association and has been criticized by experts for being scientifically flawed.

The Environmental Protection Agency (EPA), Occupational Safety and Health Administration (OSHA), World Health Organization (WHO), and International Labour Organization (ILO) have all stated that there is “no known safe level of exposure” to asbestos of any type.

Asbestos Use in the U.S.

Researchers began to see clear evidence that exposure to asbestos causes deadly diseases in the early 20th century. They observed, mainly during autopsies, that individuals who experienced prolonged exposure had extensive scarring of the lungs. As the visual evidence mounted in the 1930s, more and more medical journals ran articles linking asbestos to cancer.

Still, major industries, including the U.S. military, continued to use asbestos for a variety of structures and goods made through the 20th century. Asbestos use hit its peak in the United States from 1940 to 1975, as a massive demand for ships generated large-scale shipbuilding efforts during World War II. The construction of these ships called for large amounts of asbestos-containing materials, exposing shipbuilders and servicemen to high levels of asbestos fibers.

During the latter part of the 20th century, the U.S. government recognized how dangerous the mineral was and attempted to reduce the manufacturing of asbestos-containing materials. In 1989, the Environmental Protection Agency banned asbestos-containing products with the “Asbestos Ban and Phaseout Act of 1989.” In 1991, however, the Fifth Circuit Court of Appeals lifted most of the ban, but upheld the prohibition of new forms of asbestos use.

Although the United States hasn’t produced asbestos since 2002, the country still imports about 3,000 tons per year, mostly from Brazil.

According to the EPA, most commercial uses of asbestos are still allowed. Some examples of asbestos-containing products include:

  • Disk brake pads
  • Drum brake linings
  • Roofing felt
  • Millboard
  • Cement pipe
  • Automatic transmission components

Libby, Montana

The hazards of asbestos played out tragically in the small town of Libby, Montana. For decades, a vermiculite mine on the edge of town was the source of 200 jobs and a high level of production – workers once produced 2 million tons of ore in one year.

After 40 years of production, the industrial company W. R. Grace acquired the mine in 1963. Within two years, internal memos showed that executives knew about the dangers posed by the mine. Employees never received this information, and the company continued to tell workers and residents living nearby that they were safe.

For the people of Libby, asbestos exposure caused more than 400 deaths and 1,000 illnesses. The effects are ongoing, and the number of sick residents continues to increase. The EPA has called Libby the worst case of industrial contamination of an entire community in American history.

The plant closed in 1990, and W.R. Grace – faced with more than 270,000 asbestos-related lawsuits – filed for bankruptcy. Bankruptcy courts forced the company to set up trust funds to pay for the treatment of victims diagnosed with asbestos-related diseases.

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h2 id="whos-at-risk" class="head-divider">Who’s at Risk?

Anyone who’s come in contact with asbestos is at risk of developing an asbestos-related disease. Heavy, frequent occupational exposure is more likely to lead to the development of disease than non-occupational exposure. Researchers also consider long-term, low-level exposure as a potential threat.

Asbestos exposure occurs on the job, through second-hand exposure, or by living near a mine or processing plant. Experts consider certain occupations to be “high risk” due to the large and frequent amount of asbestos workers experience on the job.


The military widely used asbestos for decades – most ships, aircrafts, bases, and other vehicles contained it in some form. Because of this widespread usage, veterans serving in the Navy, Marines, Army, Air Force, and Coast Guard experienced exposure at some point during their service.

More than 4 million men and women worked in shipyards during World War II.The majority of Navy ships built from the 1930s to the 1970s were constructed with asbestos-containing materials, exposing these workers to high levels of asbestos for decades.


Miners work directly with asbestos in its natural form. As they remove asbestos from mines and naturally-occurring rock formations, miners disturb the extremely friable mineral and release its microscopic fibers into the air. Asbestos is no longer mined in the U.S., but the practice continues in other countries, such as Russia, China and Brazil.

Auto Workers

From disk brake pads to drum brake linings, many automotive parts contained (and may still contain) asbestos. Approximately 900,000 auto mechanics in the U.S. are thought be exposed to asbestos dust from their work on clutches and brakes.

Construction Workers

Several components of houses constructed throughout the first half of the 20th century contained asbestos. Workers who build, repair, or renovate older homes built during this time period often come in contact with asbestos-containing housing components, including: flooring, roofing, paint, and insulation.

Other occupations are also at risk of asbestos exposure:


Firefighters often come in direct contact with asbestos-contaminated drywall products, roofing materials, floor tiles, plaster, and wall insulation. Asbestos is extremely dangerous when it’s exposed to fire, which agitates its fibers and makes them airborne. These fibers endanger the lives of firefighters who can breath in large amounts in a short period of time.


Realtors come in contact with many older homes, many of which were manufactured with asbestos-containing materials. Most homes built before 1980 contain asbestos in some form, including roofing tiles, insulation, and caulking.

Teachers and Students

Schools built before the 1980s can contain asbestos as well. According to the EPA, most primary, secondary, and charter schools in the United States were built with asbestos-containing materials. The EPA’s policy is to keep remaining asbestos intact because asbestos poses more of a threat when it’s disturbed.

9/11 Volunteers

People who helped in the rescue, recovery, and cleanup of the attacks on the World Trade Center were exposed to asbestos. Firefighters, police officers, paramedics, construction workers, and volunteers who worked closer to Ground Zero were put at a great risk of asbestos exposure. An estimated 70 percent of workers who assisted in the cleanup of the site reported new or aggravated respiratory symptoms afterward.

Scientists don’t know how many fibers are needed to cause asbestos-related diseases, and they don’t yet understand why some people get sick and others don’t.

Most people who are exposed to the toxin don’t develop an asbestos-related disease. Researchers believe that such illnesses arise from a combination of environment, genetics, health, and lifestyle.

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Avoiding Exposure

Educating yourself about potential exposure sites is the best way to prevent an asbestos-related diseases from occurring. Construction and shipyard workers should be aware of hazards presented by their specific job site. Teachers working in older buildings can minimize exposure to asbestos by learning more about EPA regulations. Homeowners living in houses constructed before the 1980s can guard against exposure by avoiding asbestos-contaminated structures in the household.

Construction and Shipyard Workers

It’s important to know if you come in contact with asbestos at your job, OSHA has classified the hazards for construction and shipyard workers:

Class I: The most potentially hazardous class of asbestos jobs, Class I jobs involve the removal of thermal system insulation and sprayed-on or troweled-on surfacing, asbestos-containing materials, or presumed asbestos-containing materials.

Class II: This includes the removal of other types of asbestos-containing materials that are not thermal system insulation, such as resilient flooring and roofing materials containing asbestos.

Class III: Class III focuses on repair and maintenance operations where asbestos-containing or presumed asbestos-containing materials are disturbed.

Class IV: The fourth class pertains to custodial activities where employees clean up asbestos-containing waste and debris.

OSHA also assigns safety guidelines for each class. These guidelines require employers to create “controlled zones” designed to protect employees working with asbestos.

If you work in one of these high-risk professions, talk to your employer about OSHA classifications and standards to make sure you’re working safely. Always follow safety regulations set out by OSHA and ask your employer about additional actions you can take to protect yourself.

Teachers and Students

According to the EPA, most school buildings in the United States contain asbestos. Currently, the agency warns that removing the asbestos is more dangerous than keeping it in place, as demolition or renovation can cause the mineral’s microscopic fibers to become airborne.

The EPA does, however, set specific regulations to protect teachers and students. The Asbestos Hazard Emergency Response Act (AHERA) requires public and non-profit schools to:

  • Inspect schools buildings for contaminated material
  • Create management plans
  • Actively prevent or decrease asbestos dangers

Schools must comply with specific safety measures to comply with AHERA guidelines.

These measures include:

  • Every three years, complete an original inspection to determine whether asbestos-containing materials are present, then re-inspect contaminated materials.
  • Create, maintain, and revise an asbestos management plan documenting any asbestos findings; a copy must be kept at the school.
  • Every year, notify parents, teachers, and employee organizations of the management plan’s availability as well as any asbestos-related actions taken or planned in the school.
  • Assign a contact person to make sure the school implements its AHERA responsibilities.
  • Carry out periodic surveillance of known or possible contaminated material.
  • Make sure that trained, licensed professionals perform inspections.
  • Provide custodial staff with asbestos-awareness education.

If you’re concerned about asbestos in a local school — especially one that’s undergoing repairs or renovations — talk to school officials and learn how they are complying with AHERA.

In Your Home

It’s impossible to visually confirm if something contains asbestos. Nevertheless, if you suspect your house was manufactured with asbestos-containing materials, you have two options: leave it alone or have your home inspected by an accredited professional.

In general, the EPA recommends leaving potentially contaminated items alone, because asbestos-containing materials pose no threat if left undisturbed. However, if you’re remodeling your home, or if you have building damage, like crumbling drywall or deteriorating insulation, the EPA recommends contacting a professional.

A trained asbestos-removal professional can accurately identify and properly handle contaminated materials. He or she can also examine the material, conduct air quality tests, and remove the asbestos if need be.

Asbestos Dos and Don’ts for Homeowners


  • Leave undisturbed asbestos-containing materials alone
  • Avoid activity in areas that have damaged asbestos-containing material
  • Carefully avoid damaging or disturbing contaminated material
  • Hire trained professionals to perform repairs involving hazardous material


  • Sweep, dust, or vacuum debris that may contain asbestos
  • Sand, saw, scrape, or drill holes in contaminated materials
  • Use a power stripper on flooring that may contain asbestos
  • Sand or try to level asbestos flooring or its backing (when flooring needs to be replaced, install a new floor over it if possible

After Asbestos Exposure

If you’re concerned about past asbestos exposure – especially if the contact happened over an extended period of time – it’s a good idea to see your doctor, even if you’re not having symptoms of an asbestos-related disease.

Symptoms don’t appear until decades after exposure. When they do, the disease has usually advanced too far for the patient to receive treatment. Early detection is critical to getting effective treatment.

More Information

Many governmental agencies and non-profit groups provide comprehensive information about asbestos, including diseases, risks, and exposure prevention.

Environmental Protection Agency (EPA)
Find the phone number for your region: : Asbestos webpage:

Occupational Safety & Health Administration (OSHA)
Phone number: (800) 321-6742 Website : Asbestos webpage:

Agency for Toxic Substances and Disease Registry (ATSDR)
Phone number: (888) 422-8737 Website: Asbestos webpage:

National Cancer Institute (NCI)
Phone number: (800) 422-6237 Website : Asbestos webpage:

National Institute for Occupational Safety and Health (NIOSH)
Toll-free number: 1-800-232-4636 (1-800-CDC-INFO) Website: webpage:

If you’d like more information on asbestos exposure and mesothelioma, contact a member of our Patient Help Team. A team member will answer your questions and can even help connect you to a mesothelioma specialist.