The Missing Source of Secondary Organic Aerosols (SOAs)

Aerosol Origins. ‘Atmospheric Chemistry models have long underestimated the actual levels of organic aerosols in the air, in some cases by a factor of 10. Now, researchers at Carnegie Mellon University believe that the gap in the models involves oxidation of hydrocarbon emissions into potentially hazardous secondary organic aerosols (Science 2007, 315, 1259). Fine particulate matter in the atmosphere is composed of sulfates, primary organic aerosols such as hydrocarbons from exhaust pipes, and secondary organic aerosols (SOAs), which are more highly oxidized species.’

Carnegie Mellon Researchers Urge Regulators To Rethink Strategies for Controlling Soot Emissions. ‘Carnegie Mellon University researchers say government officials need to adopt new ways of measuring and regulating the fine particles of smoke and soot so endemic to serious health problems and the global warming crisis. In a March 2 article published in the journal Science, professors Allen L. Robinson and Neil M. Donahue report a new conceptual model for how microscopic particles behave in the atmosphere that raises new questions about current regulations.
The research found new chemical processes that occur after soot and gaseous pollutants are emitted from cars and trucks, changing the chemical and physical properties of the soot particles and creating new particulate matter. These new particles are potentially more toxic and may have a stronger influence on cloud formation that can alter the global climate.
“One of our key findings is that this chemical processing leads to more particulate matter in the air, meaning that regulators are likely underestimating how sources such as cars and trucks contribute to pollution,” said Robinson, an associate professor of mechanical engineering and engineering and public policy. “We need to take a holistic approach to regulating these sources that account for all emissions.” Accounting for these new processes improves the predictions of the models federal and state governments use to develop regulations.
“A second important finding is that the properties of this new particulate matter are different than we previously thought and potentially more toxic,” added Donahue, an associate professor of chemical engineering and chemistry.’


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