Air pollution study clears the air on diesel versus gas emissions

Oct 22, 2012 by Sarah Yang
Air pollution study clears the air on diesel versus gas emissions
Diesel exhaust contributes more to a component of smog than gasoline-fueled cars, according to a new UC Berkeley study.

(Phys.org)—Are gasoline-fueled cars or large diesel trucks the bigger source of secondary organic aerosol (SOA), a major component of smog? UC Berkeley researchers have stepped into this debate with a new study that says diesel exhaust contributes 15 times more than gas emissions per liter of fuel burned.

The study, published today in the , elucidates the contributions to air pollution from the two types of fuel emissions. The authors estimate that diesel exhaust is responsible for 65-90 percent of a region's vehicular-derived SOA, depending upon the relative amounts of gasoline and diesel used in the area.

For example, the researchers noted that in the San Francisco Bay Area, about 10 times more gas is used compared with diesel.  

SOA contributes to respiratory problems and , so pinpointing the major sources of the pollutant is important in evaluating current and future policies to reduce smog in the state.

The new findings contradict previous research that put the blame on gasoline-fueled vehicles as the predominant source of precursors that form secondary organic aerosol.

"We can now say that, while both motor vehicle sources are important for these 'secondary' particles, diesel is responsible for a larger portion, especially in regions such as the with a lot of diesel use," said study principal investigator and professor Allen Goldstein, who has joint appointments in the Department of Environmental Science, Policy and Management and the Department of Civil and Environmental Engineering.

For this study, Goldstein, who also is a faculty chemist at the Lawrence Berkeley National Laboratory, teamed up with Robert Harley, professor of civil and environmental engineering, and an expert on and air quality.

The findings stand out because the researchers were able to tease out the chemical composition of

"The data from our study contains the most comprehensive chemical detail to date on diesel and gasoline emissions," said study lead author Drew Gentner, a recent UC Berkeley Ph.D. graduate in civil and environmental engineering. "This presents many opportunities to assess the chemistry of these compounds in the atmosphere and the impacts of these sources. We expect that these findings will help policymakers improve air pollution control measures in the state, and also other parts of the world."

Explore further: Pact with devil? California farmers use oil firms' water

More information: "Elucidating secondary organic aerosol from diesel and gasoline vehicles through detailed characterization of organic carbon emissions," by Drew R. Gentner et al. PNAS, 2012.

Related Stories

EPA mandates ultra-low-sulfur diesel fuel

Jun 05, 2006

The Environmental Agency has quietly issued a rule requiring U.S. oil refineries to produce ultra-low-sulfur diesel fuel to substantially reduce emissions.

Recommended for you

Stronger action needed to transform the UK's energy system

1 hour ago

An ambitious policy package is essential for the UK to transform its energy system to achieve the deep reductions in carbon emissions required to avoid dangerous climate change, according to research led by UCL scientists. ...

Gimmicks and technology: California learns to save water

Jul 03, 2015

Billboards and TV commercials, living room visits, guess-your-water-use booths, and awards for water stinginess—a wealthy swath of Orange County that once had one of the worst records for water conservation ...

Cities, regions call for 'robust' world climate pact

Jul 03, 2015

Thousands of cities, provinces and states from around the world urged national governments on Thursday to deliver a "robust, binding, equitable and universal" planet-saving climate pact in December.

Will climate change put mussels off the menu?

Jul 03, 2015

Climate change models predict that sea temperatures will rise significantly, including in the tropics. In these areas, rainfall is also predicted to increase, reducing the salt concentration of the surface ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.