OnAir: Research Underdogs Fill Atmospheric Blind Spot

AAAR_underdogs1Andy Grieshop and Ben Murphy call themselves underdogs.

“A few years ago when we presented our research… people would just stare at us blankly,” Andy recalled.

But now, several years and publications later, the skeptical tone has changed. During a presentation at the 2010 AAAR conference in San Diego, audience members seemed encouraged by what they saw.

Andy and Ben are two members of a group of Carnegie Mellon scientists who have spent years trying to fill a big blind spot in atmospheric modeling.

Historically, most models of atmospheric air pollution significantly underestimated the amount of a specific kind of particle, called secondary organic aerosol (SOA).

“What we actually observe in the atmosphere is a factor of 3 – 100 times more than the SOA traditional models predict,” Grieshop explained.

This means that the information used by scientists and policymakers to make important pollution control decisions is not representing everything that people breathe.

According to Grieshop and Murphy, the traditional models overlook some key reactions and processes that take place as particles age and transform in the atmosphere. Most people do not breathe particles emitted directly from a tail pipe, they explained. People breathe in particles that have spent time in the air, moving and reacting with other chemicals.

“When particles dilute, evaporate and then condense back to particles, a lot about them changes,” Murphy said.

Some of these changes could be important to human health.

“Health researchers need accurate models to understand what people are actually exposed to,” Murphy said.

If SOA, as some preliminary studies suggest, is more toxic to people, the new models could be critical for protection of public health.

The new model incorporates atmospheric processes that contribute to SOA formation and does a much better job of predicting what people breathe.

“It’s pretty close to right-on,” Grieshop said, “in terms of matching what we observe in the atmosphere.”

Though more research needs to be done to “drill deeper” into atmospheric processes that may change particles, both scientists agree that this finding could have a big impact.

Their research is already being incorporated into state and local air quality models that are used to manage and control pollution.

“You never really expect that your specific research in atmospheric chemistry may be important for national policy so early on in your career,” Grieshop said excitedly.

“This has been a really great opportunity for us to make a difference.”

About the Author: Becky Fried is a science writer with EPA’s National Center for Environmental Research. Her OnAir posts are a regular “Science Wednesday” feature.