Tests of simple models based on the sped-up reactions have resulted in increases as high as 30 percent in the models' predicted levels of ozone, a crucial ingredients of smog, she said. Still, we think that 30 percent is a fairly significant increase, and further study is warranted. Many of the nation's large cities and urban regions use air quality models to predict the outcome of pollution control efforts such as requiring vehicle inspections or providing special lanes for carpooling, said Roger Atkinson, a professor in the departments of environmental sciences and chemistry and director of the Air Pollution Research Center at the University of California at Riverside. The models also are used to forecast future pollution levels and help policy-makers decide whether regulations may be required in advance to keep a city or region within federal pollution standards. The models take into account the reactions of smog-forming chemicals such as a myriad array of volatile organic compounds emitted by cars, Andino said.
Gases can react to form compounds that essentially condense and form very small, liquid particles.
Her experiments show the introduction of different types of small particles sped up the reaction rates of several types of alcohol that are ingredients of gasoline. Other gasoline ingredients, including an aromatic compound and an alkane, did not react more quickly, but only a few varieties were tested, Andino said. The particles in the tests included ammonium nitrate and ammonium sulfate aerosols, both common particles in urban areas, she said. Atkinson said Andino's results would have little impact on the computer models in use by cities currently, but they are intriguing. I think the other line is that it probably needs to be confirmed by other labs.