Asphalt

Asbestos in Asphalt and Other Building Materials

Asphalt is a material made from petroleum. The majority of asphalt in the U.S. is used for road construction. The remaining asphalt has been used in building construction, primarily roofing work. Both forms of asphalt have had asbestos fibers included in their production process.

Prior to the 1980s, asbestos fiber was a significant component of asphalt roofing tiles. The addition of asbestos provided extra strength and durability to the material in addition to making it much more flame resistant.

From 1960 until the late 1970s, asbestos fiber was also added to the asphalt used in road construction, particularly in northern states that experience harsh winters where the practice of salting the roadway during freezing weather was standard procedure. As salt causes rapid breakdown of asphalt road surfaces, asbestos fiber was seen as a way to strengthen and reinforce the pavement. New Hampshire was the last state to use asbestos fibers in road construction materials; this was discontinued in 1979.

Although asbestos in road asphalt was widespread, roads and highways are not thought to be a major source of asbestos-related illnesses, accounting for no more than 3% of all cases of asbestos-related illness. Building materials like asphalt roofing shingles are thought to be a much greater public health risk. The good news is that asbestos roofing materials are far less likely than other forms of asbestos to become friable. Friability is a state in which the asbestos material crumbles into dust and releases fibers into the environment. Under National Emissions Standards for Hazardous Air Pollutants (NESHAP) guidelines, asphalt roof shingles are a Category I substance, and pose a lower level hazard than asbestos board or other types of asbestos insulation. However, there are still strict environmental regulations governing the disposal of asbestos-containing asphalt shingles. Prior to replacing a roof or demolishing a structure in which such materials may be present, it is usually necessary to have an inspection done by an authorized state employee.

Asphalt Products Containing Asbestos

The following partial list of asphalt products were known to contain asbestos:

Product Name Start Year End Year
Flintkote Flintkote #19 Asphalt

Hazards Associated with Asphalt Products

Individuals working on road crews in the 1960s and 1970s in the northern states were exposed to asbestos in asphalt used for roads. Despite the relatively low number of reported cases, this is still an area of exposure that should not be discounted. Road crews tearing up or repairing older asphalt road surfaces would be at higher risk, as the asbestos in the asphalt would be more likely to become worn and to break off into the air.

Roofers and other construction workers are at even higher risk, but the highest exposure risk is associated with demolition and repair work. As with roads, it is old and damaged asbestos that poses the highest danger, and individuals who have torn down buildings or repaired old roofs are the most likely to have been exposed to friable asbestos fibers.

Sources

Bowker, Michael. Fatal Deception: The Untold Story of Asbestos (New York: Touchstone, 2003)
N/A. "Asbestos in Building Roofing Materials." Inspect-A-Pedia http://www.inspectapedia.com/sickhouse/asbestoslookG.htm. Retrieved 3 January 2011.

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