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Air Quality UpdateApril 1, 2002
Ozone Implementation Draws Precursor, Geographic DebateOne of the EPA staff papers developed to explore options for the eight-hour ozone standard has opened debate over local exemptions for emissions control programs. Focusing largely on programs that targeted volatile organic compound (VOC) reductions under the one-hour ozone standard, this new round of debates highlights the differences between two major strategies: nitrogen oxides-oriented vs. VOC-oriented and regional control vs. local control. The principal programs at issue include vehicle inspection and maintenance programs--initiatives that generated considerable controversy in their own right--and other curbs on emissions that applied to a host of businesses. EPA regulators are assessing the legality of exempting local areas from these and an assortment of other prescriptive measures written into the Clean Air Act Amendments of 1990. One of the papers EPA is developing to address implementation of the new ozone marks deals with the flexibility the agency can offer to state and local areas in pursuing attainment strategies. One provision that is drawing specific attention is whether the agency will require State Implementation Plans that call for another 15 percent reduction in VOCs--a requirement that many areas struggled to realize during the early years after the CAAA. Small businesses, large "smokestack" industries, state and metropolitan transportation programs, and other elements critical to the SIP process were challenged to meet the prescriptive requirements of the Act. While EPA officials appear to be testing the waters of flexibility, they point out that the CAAA may limit this approach. In addition, an earlier Supreme Court ruling addressing the 1997 standards was critical of the agency for placing minimal emphasis on prescriptive requirements. On a related front, the chairman of the Northeast's Ozone Transport Commission has written to the EPA air chief that regional considerations of transported pollution must assume more weight in developing attainment strategies. Arthur Rocque, Jr., OTC chairman, notified EPA's Jeffrey Homestead that NOx control is more critical than VOC limits in addressing downwind ozone transport, and the wide array of local VOC measures should be reconsidered. Fuel Booster Cuts Diesel EmissionsWhat started out as a combustion-boosting additive for locomotives may carry an unintended surprise benefit. A Missouri railroad organization reports that an additive focusing on fuel efficiency appears to reduce diesel exhaust emissions considerably. W.D. Spencer, president of the Terminal Railroad Association (TRRA) in St. Louis, announced that a series of operational tests using the chemical component known as RxP pointed to locomotive emissions reduction of between 40 percent and 90 percent. Adding RxP to diesel fuel used in graders and other off-road mobile sources equipment produced an emissions savings of between 50 percent and 70 percent according to the association's president. Constituents of diesel emissions that recorded reductions included carbon monoxide, hydrocarbons, and [nitrous] oxides. The TRRA now applies the additive to all its locomotives fueled in St. Louis. In addition to the environmental benefits tied to emissions mitigation, the association notes that net fuel savings should generate about $100,000 each year. Ultra-Sensor Identifies Missing NOxOnly about half of the inventory of nitrogen oxides in the atmosphere is accounted for in today's air pollution models. Chemists at the University of California at Berkeley think they have found and identified the NOx they claim has been missing. Since NOx reacts with natural and artificial carbon compounds to form ozone, acid rain precursors and other chemical components, the specific identification of NOx radicals is critical to research efforts, and ultimately, to pollution control. The Berkeley team has employed an ultra-sensitive chemical sensor to identify the missing link in NOx identification. Deploying in two vastly different environments, the sensors were placed in a remote forested area in the Sierra Nevada's and in downtown Houston. In both cases the researchers identified large amounts of alkyl nitrates, an organic nitrogen oxide compound thought to be only a minor precursor of ozone. In the city, combining industrial hydrocarbons and NOx forms the alkyl nitrates. In forested areas however, the compound is a product of tailpipe emissions of NOx and natural hydrocarbons emitted from trees. Monitors in use today measure only the total of all NOx. Confirming the exact chemistry of NOx and its constituents will contribute to better predictive models and more efficient attainment strategies, according to the California team. |
