Asbestos Overview

Asbestos - How to Identify it & What to Look For

Locating and identifying asbestos is often a matter of first determining when a building was constructed, as asbestos-containing products are often difficult to identify by sight. Asbestos-containing construction materials were widely used until the mid-1980s. To conclusively identify asbestos-containing materials, samples of the suspected materials should be examined by a trained professional.

Locating Asbestos

The use of asbestos in construction materials was so widespread throughout much of the twentieth century that almost any construction material in a residential, commercial or public building constructed between 1920 and 1986 may have been built using asbestos-containing materials.

Some common asbestos-containing construction materials include:

    Asbestos Roofing Tile
    Asbestos Roofing Tile
  • Roofing materials: asphalt shingles, roofing felt, base flashing and roofing adhesives may all contain asbestos in varying amounts.
  • Exterior cement siding, including shingles, clapboard and other cement products may contain between 12% and 15% asbestos.
  • Acoustic plaster and finishers used in interiors have a characteristic popcorn-like texture, and may contain asbestos.
    • Asbestos Tape on Pipes
    Asbestos Tape on Pipes
  • Adhesives, caulk, putty, tape and patching materials. These were most commonly used in locations subject to high temperatures.
  • Pipes with asbestos tape.
  • Insulation products, including loose or batt insulation used in walls, seal and duct coverings, pipe insulation, and electrical insulation may contain asbestos.
  • Vinyl tiles (wall, floor and ceiling), and tile underlay.

Products that contain asbestos tend to look just like products that don't contain it. In most cases, the age of the building and materials is an important clue in determining whether or not asbestos-containing products are present. For example, in buildings of the appropriate age (built between 1920 and 1986), asbestos is likely to be present in any location where protection from heat and fire was required, such as underneath and around fireplaces and furnaces.

For more information about home construction products that may contain asbestos, please see "Asbestos - Common Locations in the Home". For an extensive list of construction materials and other products that may contain asbestos, see "Products Containing Asbestos."

Is it Dangerous? What to Look For

The presence of asbestos-containing construction materials is not always a health hazard. The nature of asbestos fibers is such that they are dangerous only if they are airborne, as it is only then that they may potentially be inhaled or otherwise ingested.

In most cases, asbestos-containing construction materials and other products are dangerous only if the asbestos they contain is exposed, and if the materials are in poor condition.

If asbestos-containing materials are in good condition, then the asbestos fibers they contain are usually trapped within the matrix of the material. In these cases fibers are unlikely to become airborne.

The types of products that contain asbestos also contribute to the hazard level of the substance. For example, asphalt roofing shingles, which contain very low levels of asbestos, are typically non-hazardous, because asbestos fibers are embedded within the material and unlikely to become airborne.

However, materials such as batt insulation are much more hazardous, because asbestos fibers are generally loosely held within the matrix of the material, and are much more likely to become airborne if the material is disturbed in any way.

Generally, asbestos-containing materials are safe as long as they are in good condition and are left undisturbed. However, any cracks, chips, holes and other disturbances in products such as asbestos tile and cement products can allow asbestos fibers to become airborne. Any suspected asbestos-containing materials that are damaged or very old should be considered a potential hazard.

Identifying Asbestos

Conclusively identifying products that contain asbestos is difficult, simply because it is not possible to confirm that a product contains asbestos by sight alone. Asbestos can only be conclusively identified by looking at it under a special type of microscope operated by someone who is trained to identify the substance. Often the only clue as to whether a particular material contains asbestos is its age. Any products that appear to be more than twenty years old (or are known to have been placed prior to 1986) may potentially contain asbestos.

Asbestos fibers

If you suspect that asbestos is present, it is best to have the suspected asbestos-containing materials professionally tested. The material should be sent to an EPA-approved laboratory. Note that the samples themselves should be taken by a trained professional to ensure that the building is not contaminated by airborne asbestos fibers. Taking samples of asbestos yourself may be more hazardous than leaving the material undisturbed if you are not trained to handle asbestos-containing materials.

In the meantime, it is best to assume that the material does contain asbestos, and handle it cautiously. If the building was constructed or remodeled in the period between 1920 and 1986, it is possible that some construction materials contain asbestos. If the building was constructed in the 1950s or 1960s, it is highly likely that asbestos is present, as these decades saw the most widespread use of asbestos-containing construction materials.

Please see "Asbestos Abatement/Removal" for information about removing asbestos safely.

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