Irvine, Calif., Feb. 21, 2012 Airborne gases get sucked into stubborn smog particles from which they cannot escape, according to findings by UC Irvine and other researchers published today in the Proceedings of the National Academy of Sciences.
The results could explain a problem identified in recent years: Computer models long used by the U.S. Environmental Protection Agency, California air regulators and others significantly underestimate organic aerosols the major component of smog particles. Such pollution blocks views of mountains and has been linked to everything from asthma to heart attacks. It is also the largest unknown in climate change calculations.
"You can't have a lot of confidence in the predicted levels right now," said lead author Veronique Perraud, assistant project scientist to pioneering UCI air chemist Barbara Finlayson-Pitts. "It's extremely important, because if the models do a bad job of predicting particles, we may be underestimating the effects on the public."
An independent expert who reviewed the research for PNAS agreed.
"The conclusions are highly significant," said Purdue University atmospheric chemist Paul Shepson. "This paper should and, I expect, will have a big impact. We've known for nearly a decade that there's a huge difference between what's in the models and what's actually in the air. Thanks to this paper, we have a much better idea of why."
Scientists at UCI, a U.S. Department of Energy laboratory and Portland State University combined pinene, a common ingredient in household cleaners such as Pine Sol and outdoor emissions, with oxides of nitrogen and ozone to mimic smog buildup.
Models used by regulators for decades have assumed that organic aerosols in such pollution form liquid droplets that quickly dissolve potentially unhealthy gases. But the new work found that once gases are sucked into a particle, they get buried deeper and deeper.
|Contact: Janet Wilson|
University of California - Irvine