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EPA limits industrial benzene emissions.

EPA limits industrial benzene emissions

For roughly 15 years, the Environmental Protection Agency has wrestled with how to regulate nonoccupational exposures to benzene, a human carcinogen and the sixteenth most widely used chemical by U.S. industries. Last week, EPA finally unveiled a sweeping control strategy to cut industrial air emissions of the hazardous chemical by 90 percent. These benzene rules also establish a new health-based standard by which the agency will begin regulating other toxic industrial air pollutants.

These controls do not, however, address the 80 percent of outdoor benzene pollution emitted by gasoline vapors as motor vehicles are fueled and driven.

The final rules, announced Aug. 31 by EPA Deputy Administrator F. Henry Habicht, give several major benzene-using industries two years to implement required controls. Emissions from plants that recover by-products of coke production (such as tar, ammonia and light oil) represent the single largest industrial source of benzene in air. Newly required controls -- such as blanketing surfaces of stored liquid benzene with a layer of a heavy gas to limit evaporation -- should cut annual emissions from this source from about 18,700 tons to just 550 tons, or about 97 percent. New controls should also reduce emissions from other benzene-storage vessels by up to 60 percent and limit by nearly 70 percent the evaporative leaks -- from pumps, valves and other equipment -- in chemical plants and petroleum refineries.

Habicht also proposed rules for controlling between 65 and 95 percent of the emissions from all other industrial sources: facilities that treat chemical wastes, operations that transfer benzene or gasoline (which contains from 2 to 5 percent benzene) from bulk terminals and production plants to a user's storage tanks, pharmaceutical manufacturing and tire manufacturing.

These rules are EPA's first to comply with the "vinyl chloride decision," handed down by the District of Columbia Court of Appeals in July 1987. The court ordered EPA to provide an "ample margin of safety" when regulating hazardous industrial pollutants under the Clean Air Act. Moreover, it said, risk calculations used to derive these standards must be based purely upon health considerations, not costs or technology constraints.

Expected to cost about $1 billion to install, the new controls should reduce leukemias from industrial benzene emissions from an anticipated four annually to at most one every three years, according to Gerald A. Emison, EPA's director of air quality planning and standards, based in Durham, N.C.
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Author:Raloff, Janet
Publication:Science News
Date:Sep 9, 1989
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