Airborne Sea Salt Particles Influence Air Pollution
NSF-supported scientists have shown that sea salt particles — a common ingredient of coastal and ocean air — undergo a previously unrecognized chemical reaction in daylight to release chlorine molecules, which can influence ozone levels in the lower atmosphere.
Researchers Barbara Finlayson-Pitts and Donald Dabdub of the University of California at Irvine have discovered that, in sunlight, chlorine molecules decompose into highly reactive chlorine atoms. When these atoms are formed in the presence of pollutants emitted from fossil-fuel energy sources such as oil, coal and gasoline, they may lead to the formation of ground-level ozone. Because ground-level ozone has proven detrimental health effects at quite low levels, both state and federal authorities have established air quality standards for this pollutant.
“The ocean is two-thirds of the earth’s surface, so to understand global climate issues and the chemistry of air pollution in coastal regions, you need to take into account the role of sea salt particles,” explains Finlayson-Pitts. Dabdub plans to introduce the information on sea-salt chlorine creation into a computer model that analyzes and predicts the air quality of the South Coast Air Basin of California — a populous coastal area that records some of the highest levels of air pollution in the U.S. — to gauge its effects on ozone levels and other pollutants.