MTBE, Ethanol Don’t Reduce Auto Pollution

Published July 1, 1999

After nearly a decade of Environmental Protection Agency (EPA) mandates to use the oxygenates MTBE (methyl tertiary-butyl ether) and ethanol in reformulated gasoline, a committee of the National Research Council (NRC) has determined the additives do little to reduce vehicle pollution emissions.

“Motor vehicle emissions of chemicals that form ozone pollution have decreased in recent years,” said committee chair William Chameides, regents professor of earth and atmospheric sciences at the University of Georgia. “But that’s largely due to better emissions control equipment and components of reformulated gasoline–other than oxygen additives–that improve air quality. Although additives do reduce some pollutants from motor vehicle emissions, the oxygenates appear to have little impact on lowering ozone levels.”

The study has added fuel to a growing nationwide debate over the costs and benefits of oxygenated fuels. In March, California Governor Gray Davis called for an end to the use of MTBE, which has been found in the state’s groundwater and reservoirs. (See “California governor orders phase-out of gas additive,” Environment News, May 1999.) While there is conflicting research on the chemical’s effects on human health, even at low concentrations the chemical gives water an unpleasant odor and taste, rendering it undrinkable.

The result of EPA’s oxygenate mandate– which the NRC has now determined to do more harm than good– has been a scramble by oil industry leaders and lawmakers at the local, state, and federal levels to undo the effects of the agency’s mistake. Mobil Oil has signed a consent agreement to remove MTBE from Santa Monica, California’s drinking water. Class action suits have been filed against refiners and distributors in both California and North Carolina, some of whom were reportedly reluctant to use MTBE but felt EPA gave them no alternative. Bills have been introduced in Congress to relax the oxygenate mandate.

In a May 4 address to Congress, Representative Cliff Stearns (R-Florida) urged his colleagues to “move to . . . end the mandates for oxygenates which, by the way, many scientists contend do nothing to reduce air pollution from the majority of cars on the road today.”