SACRAMENTO – The California Air Resources Board (ARB) today strengthened its air toxic control measure for asbestos (https://ww3.arb.ca.gov/regact/asbestos/asbestos.htm) by eliminating the use of asbestos-containing ultramafic rock for surfacing operations, such as road covering or landscaping.

       Dr. Alan Lloyd, ARB Chairman, said, "This amendment improves the existing control measure and better protects the public from the cancer-causing effects of asbestos-laden dust from gravel roads, parking lots and landscaping."

       Asbestos has been known to cause lung cancer and mesothelioma, a cancer of the lining of lung tissue that is nearly always fatal.  The ARB's action limits the asbestos content of serpentine rock to less than 0.25 percent, the detection limit of current test methods.

       Serpentine rock, a subset of ultramafic rock and commonly found throughout California, has been used both to cover unpaved roads and as bedrock material.  While today's action eliminates the further use of all ultramafic rocks where public exposure may occur, it does not affect the use these materials in asphalt or as base material, such as drain rock where public health is not at risk.  Sellers of rock containing more than 0.25 asbestos must provide written notice that the rock cannot be used in surfacing applications.

       The amendments also give local air quality agencies the flexibility to exclude or include rock quarries from the rules based on additional testing.  According to ARB data, there are about 200 mines and quarries in California that produce aggregate subject to the asbestos rules.  Of these, five may be impacted economically by today's amendment.  Staff estimates the costs of asbestos testing to range between 6 and 10 cents per ton of rock sold for surfacing.

       The ARB identified asbestos as a toxic air contaminant with no safe threshold level in 1986.  In 1990, the ARB adopted the present rules that limit the asbestos content of serpentine rock to 5 percent or less for any surfacing application.

       The ARB revisited the asbestos rule after numerous public complaints by citizens of El Dorado County who expressed concern about airborne asbestos exposure from quarries in the county.  Asbestos is the common name for a group of naturally occurring minerals that can separate into thin, inhalable fibers.  The principal forms of asbestos include: chrysotile, crocidolite, amosite, tremolite, actinolite and anthrophyllite.   Chrysotile is the common form of asbestos found in El Dorado County, although some other forms have been found during searches by state officials.   All forms of asbestos are harmful to human health.

        In November, the ARB will consider an air toxic control measure for asbestos dust from construction activities, quarries and mining operations.