Researchers at UC Davis have established, for the first time, a link between toxic substances that pollute the air and what causes them.

The research, announced Monday by the California Air Resources Board and the Electric Power Research Institute, holds the potential to better regulate sources of air pollution – an issue of great import to the asthma-plagued Sacramento and San Joaquin valleys.

"People have looked at direct emissions from sources – like taking things right out of tailpipes and out of other sources," said Anthony Wexler, director of the Air Quality Research Center at UC Davis, who conducted the study with fellow UC Davis professor Kent Pinkerton.

"What distinguishes us is that we're actually sampling right from the atmosphere in the way we breathe," Wexler said. "Because you don't put your mouth up against a tailpipe."

Establishing a picture of what toxic brew is in the atmosphere and what sources it originates from, plus how those chemicals react, is key to fine-tuning environmental regulation, as well as the costs borne from it, said Will Barrett, policy manager with the American Lung Society.

"The findings are significant in that they underscore the importance of controls on things like wood burning and transportation sources of the most harmful particles that affect the Valley," said Barrett.

"This is especially important for the Central Valley since it is facing some of the more daunting air quality challenges in the nation, particularly due to fine-particulate pollution," Barrett said.

Wexler said the research is seen as a tool for regulatory agencies. "This was one of my objectives – to help regulators figure out which sources to regulate so that we're primarily regulating sources that have a high toxicity and not so much the sources of low toxicity," he said.

Someday, the research may have an effect on mitigating asthma rates.

An estimated 11.9 percent of Californians report that they have been diagnosed with asthma at some point in their lives, compared to the national average of 10.1 percent, according to California Air Resources Board data.

The UC Davis research sampled air in Fresno during four weeks in the summer of 2008 and four during the winter of 2009. Mice were exposed to the samples of toxic particulate matter that were captured in order to establish what effect the particles had on their lungs.

The research found that in summer the culprits causing the most toxic air pollution were vehicle emissions and the use of charcoal briquets. Biomass burning for winter heating and vehicle emissions were identified as the worst culprits in the winter.

The recent evolution of instruments known as single particle mass spectrometers made the study possible. Those instruments analyze the composition of chemicals in the atmosphere and 10 of them were used in the study.

"That let us look at the chemical composition of these particles very quickly," Wexler said.

Though promising, Wexler said, the research is preliminary.

"We need more studies – this is the first time anyone has done anything like this. Other people need to do similar studies, using the same instrumentation, and in other cities to make sure the results are robust," he said. "Because you're not going to make any big regulatory moves based on one experiment."

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