Release 99-20
June 24, 1999


Allan Hirsch
Jerry Martin
(916) 322-2990
ARB Requires Labeling of Gasoline with MTBE

        SACRAMENTO The California Air Resources Board (ARB) today approved a regulation requiring service stations to post labels on pumps dispensing gasoline formulated with  the fuel additive MTBE.  The labels are intended to help motorists who want to choose whether or not to purchase gasoline that has been made with the fuel additive.

        "Cleaner-burning gasoline can be made without MTBE.  The MTBE labels at service stations will enable motorists in the near future to see that they do have choices over the kinds of gasoline they can buy," ARB Chairman Dr. Alan Lloyd said.

        MTBE (methyl tertiary butyl ether) is an oxygenated additive that helps gasoline burn more cleanly.  While not specifically required, MTBE has been widely used in California gasoline since 1992.  Studies of groundwater contaminated by gasoline from leaking underground tanks have found that MTBE contaminates groundwater more readily than other fuel components.  At low levels, MTBE renders drinking water unusable.  A 1998 University of California study recommended that MTBE use be phased out.  In March, Governor Gray Davis declared that MTBE poses an environmental risk and ordered that its use be discontinued in California by the end of 2002.

        Governor Davis' order also directed ARB to develop a regulation to require service stations to identify gasoline with MTBE so that "consumers can make an informed choice on the type of gasoline they purchase."

        The ARB regulation will require service stations selling fuel formulated with MTBE to post a label saying, "Contains MTBE.  The State of California has determined that the use of this chemical presents a significant risk to the environment."  Unlabeled gasoline could only contain residual amounts of MTBE (not exceeding 0.6 percent by volume) that could get into the gasoline during storage or transport in tanks and pipelines that previously held fuel with the additive.  Stations that do not post labels must keep records verifying they have taken shipments of non-MTBE gasoline.  Stations selling gasoline formulated with MTBE must post labels by autumn 1999.

        Most California gasoline currently contains about 11 percent MTBE by volume.  Increasing amounts of non-MTBE gasoline are expected to be available over the next three years as refineries make modifications needed to make commercial quantities of fuel without MTBE.  The phase out of MTBE will not affect the benefits from California's cleaner-burning gasoline, which reduces smog-forming emissions from motor vehicles by 15 percent and reduces cancer risk from exposure to motor vehicle toxics by about 40 percent.

        Also today, the Board eliminated a seven-year-old requirement for the use of gasoline containing an oxygenated additive such as MTBE in winter months in the Lake Tahoe area.  The use of oxygenated gasoline reduced wintertime levels of carbon monoxide at Lake Tahoe that exceeded federal and state health standards.  An ARB staff analysis determined that cleaner motor vehicles meeting ARB's emission standards will now enable the Lake Tahoe region to remain in attainment with federal and state carbon monoxide standards without an oxygenated gasoline requirement.


        The Air Resources Board is California's air pollution control agency.  The ARB's mission is to promote and protect public health, welfare, and ecological resources through effective reduction of air pollutants while recognizing and considering effects on the economy.  The ARB oversees all air pollution control efforts in California to attain and maintain health based air quality standards.

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