What’s in the mix?
Analyzing gases in the air provides valuable information for curbing pollution
By Jane Palmer
Aerosols—those microscopic particles suspended in the air—might measure a mere fraction of the width of a human hair, but their consequences can be dire, according to CIRES Fellow and associate professor Jose- Luis Jimenez. “They affect health in so many ways,” he said. “When people breathe in these particles, they can lead to heart disease, asthma or lung cancer.”
In a quest to understand the origins and behavior of a particular type of aerosols—organic aerosols—Jimenez and his team used advanced instrumentation such as aerosol mass spectrometry to tell them about the mix of chemicals in the air at a site in Pasadena, Calif. Their month-long study was part of CalNex 2010 (California Research at the Nexus of Air Quality and Climate Change).
“In Los Angeles the air quality has improved a lot over the years, and the steps which have led to the improvement have been strongly guided by the results of these once-a-decade studies,” Jimenez said. As scientists and policy makers have gained a better understanding of the causes of air pollution, they’ve initiated regulations such as requiring truck emissions to be cleaner and banning the use of certain solvents, he said. “But most
“Aerosols affect health in so many ways. When people breathe in these particles, they can lead to heart disease, asthma or lung cancer.”
— CIRES Fellow
Jose-Luis Jimenez
of the low-hanging fruit has been taken, and although the air quality has improved substantially, it is still bad for you.”
An important part of the mission of Jimenez’ work, and of the larger CalNex study, is to shed light on the causes of air pollution, opening the way to further solutions, Jimenez said. And, even though it typically takes scientists a few years to analyze and interpret the data they collect in such studies, Jimenez and his team have already observed a surprising trend. “It is different from what we expected,” he said. “We
thought that since we were going to Pasadena, which is not far from downtown L.A., it was going to look nearly the same as when we are in the middle of a city, like in downtown Mexico City.”
Instead of a replica of city air pollution, however, the scientists found the atmosphere was already “aged”—chemical reactions had majorly changed the mix of gases and particles, said Jimenez. Scientists typically thought that the mix of pollutants was relatively static and that, although it aged eventually, the process took a long time, he said. “But since the air only takes two or three hours to come from downtown L.A., the results suggest pollution ages very quickly in the atmosphere.”
If the current observations are backed up by a full analysis of the data, it could influence the way that both scientists and policy makers address poor air quality, Jimenez said. They would no longer be able to think of the air people breathe in Pasadena as the same as being dominated by the direct emissions from cars, trucks and industry, he said. “So now it is different chemicals and effects that you need to worry about.“
