The introduction of cleaner-burning gasoline in California has significantly reduced airborne concentrations of benzene, a known human carcinogen, the California Air Resources Board (ARB) announced today.

        Average benzene concentrations at 11 monitoring stations in Northern California were more than 50 percent less in Spring 1996 than in Spring 1995. While factors such as weather and the time of year affect benzene levels, the sharp 1996 drop primarily is due to cleaner-burning gasoline, which contains about half as much benzene as conventional gasoline.

        "Northern Californians are breathing cleaner and healthier air than they were a year ago. Simply put, cleaner-burning gasoline is doing its job," ARB Chairman John D. Dunlap said.

        "The biggest beneficiaries of cleaner-burning gasoline are California's children. Because they will grow up breathing cleaner air, they will experience a much lower lifetime exposure to cancer- causing benzene than their parents," Dunlap said.

        Benzene, a colorless gas, is one of the many chemicals that make up gasoline. Leukemia is the form of cancer most commonly associated with benzene exposure. About 90 percent of airborne benzene results from gasoline. Benzene enters the air through tailpipe emissions and through evaporation, such as during refueling.

        ARB required California's oil refineries to begin making cleaner-burning gasoline by March 1, 1996. By late March, cleaner-burning gasoline largely had replaced previous gasolines throughout the state. All gasoline sold in California now must meet ARB's cleaner-burning specifications.

        Benzene levels in Southern California declined sharply in 1995 following the introduction of federal reformulated gasoline, which has the same low benzene content as California's cleaner-burning gasoline. Southern California switched to the state's cleaner-burning gas at the same time as Northern California. Benzene concentrations at nine Southern California monitoring stations in Spring 1996 averaged more than 50 percent less than in Spring 1994, the last year that conventional gasoline was used in the region.

        ARB estimates that the use of cleaner-burning gasoline will reduce human cancer risk from exposure to benzene and other toxics from motor vehicles by 30 to 40 percent. Cleaner-burning gasoline also reduces smog-forming emissions from motor vehicles by 15 percent (about twice the benefits of federal reformulated gasoline). The 15 percent reduction is comparable to removing 3.5 million motor vehicles from California's roads.

        The extra expense of producing cleaner-burning gasoline has added about 5 to 8 cents per gallon to the price of gasoline. Repeated testing also has verified that the gasoline reduces average fuel economy by 1 to 3 percent.

        ARB will continue to monitor air quality to assess the effectiveness of cleaner-burning gasoline. Average benzene concentrations are determined quarterly at each of 20 monitoring stations. An assessment of the effect of the fuel on ground-level ozone, the major component of smog, will commence this summer, when ozone levels reach their peaks.

        In Northern California, benzene concentrations are measured at stations in Bakersfield, Chico, Concord, Fremont, Fresno, Modesto, Richmond, Roseville, San Francisco, San Jose and Stockton. Southern California monitoring stations are located in Burbank, Chula Vista, El Cajon, Los Angeles, Long Beach, Rubidoux, Santa Barbara, Simi Valley and Upland.

        The Air Resources Board is a department of the California Environmental Protection Agency. 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. ARB oversees all air pollution control efforts in California to attain and maintain health-based air-quality standards.