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Controlling Asbestos Exposure

Workers are likely to be exposed to asbestos during demolition operations. Heavy exposures tend to occur in the construction industry and in ship repair, particularly during the removal of asbestos materials due to renovation, repairs, or demolition. This exposure creates a very real danger to the safety and health of workers.

What is Asbestos?

Asbestos is the name given to six naturally occurring incombustible minerals that are resistant to heat and corrosion.

Watch this short video on the hazards created during a demolition project due to asbestos.
(Click to play video)

Asbestos minerals formed millions of years ago when heat, pressure, or chemical activity changed the physical and chemical characteristics of pre-existing rock. Unlike other minerals, which consist of tightly bound crystals, asbestos minerals are characterized by the presence of densely packed bundles of fibers.

On July 12, 1989, the U.S. EPA issued a final rule banning some, but not all, asbestos-containing products. For additional information, please visit the U.S. EPA: Asbestos page.

Asbestos Health Hazards

Asbestos is well recognized as a health hazard and its use is now highly regulated by both OSHA and EPA. Asbestos fibers associated with these health risks are too small to be seen with the naked eye. Breathing asbestos fibers can cause a buildup of scar-like tissue in the lungs called asbestosis and result in loss of lung function that often progresses to disability and death.

Asbestos also causes cancer of the lung and other diseases such as mesothelioma of the pleura which is a fatal malignant tumor of the membrane lining the cavity of the lung or stomach. Epidemiologic evidence has increasingly shown that all asbestos fiber types cause mesothelioma in humans.

Microscopic view of lung tissue with asbestosis. (Source CDC)
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CT image of advanced mesothelioma due to asbestos exposure
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Hazard Location

Asbestos has been used in products, including plaster, cement, and caulking.

The hazard may occur during renovating or demolishing buildings or ships; cleanup from those activities; contact with deteriorating asbestos-containing materials; and during cleanup after natural disasters. Asbestos has been used in products, such as insulation for pipes (steam lines for example), floor tiles, building materials, and in vehicle brakes and clutches.

Some materials are presumed to contain asbestos if installed before 1981. Examples of these materials, as well as other presumed asbestos-containing materials, are:

  • thermal system insulation
  • roofing and siding shingles
  • vinyl floor tiles
  • plaster, cement, putties and caulk
  • ceiling tiles and spray-on coatings
  • industrial pipe wrapping
  • heat-resistant textiles
  • automobile brake linings and clutch pads

Reducing Asbestos Hazards

Asbestos - A Matter of Time - 1959
(Click to play video)

Airborne levels of asbestos are never to exceed legal worker exposure limits. There is really 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 can cause injury of disease; every occupational exposure to asbestos contributes to the risk of getting an asbestos-related disease.

Where there is exposure, employers are required to further protect workers by:

  • establishing regulated areas,
  • controlling certain work practices and
  • instituting engineering controls to reduce the airborne levels.

The employer is required to ensure exposure is reduced by:

  • using administrative controls and
  • provide for the wearing of personal protective equipment.

Medical monitoring of workers is also required when legal limits and exposure times are

Exposure Limits

Time-weighted average limit (TWA): The employer must ensure that no employee is exposed to an airborne concentration of asbestos in excess of 0.1 fiber per cubic centimeter of air as an eight (8) hour time-weighted average (TWA).

Excursion limit: The employer must ensure that no employee is exposed to an airborne concentration of asbestos in excess of 1.0 fiber per cubic centimeter of air (1 f/cc) as averaged over a sampling period of thirty (30) minutes.


Employers should conduct initial and annual training for all employees who are likely to be exposed to asbestos in excess of Permissible Exposure Limits (PELs) and all employees who perform Class I through IV asbestos operations.

The training program must be conducted in a manner that the employee is able to understand. Employees must be informed of the following:

  • methods of recognizing asbestos
  • health effects associated with asbestos exposure
  • relationship between smoking and asbestos in producing lung cancer
  • nature of operations that could result in exposure to asbestos
  • importance of necessary protective controls to minimize exposure including, as applicable:
    • engineering controls
    • work practices
    • respirators
    • housekeeping procedures
    • hygiene facilities
    • protective clothing
    • decontamination procedures
    • emergency procedures
    • waste disposal procedures
    • any necessary instruction in the use of these controls and procedures where Class III and IV work will be or is performed (the contents of EPA 20T-2003, "Managing Asbestos In-Place" July 1990 or its equivalent in content)
  • purpose, proper use, fitting instructions, and limitations of respirators as required by 29 CFR 1910.134


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. What is the name given to a group of naturally occurring minerals that are resistant to heat and corrosion?

2. Breathing asbestos fibers can cause a buildup of scar-like tissue in the lungs called _____.

3. What may occur if workers are exposed to asbestos in duration as short as a few days?

4. Which of the following is required by OSHA where there is exposure to asbestos?

5. The employer must ensure that no employee is exposed to an airborne concentration of asbestos in excess of _____ as an eight (8) hour time-weighted average (TWA).

Have a great day!

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