Gas Worse Than Diesel For Creating Aerosols In Air

Gasoline-fueled vehicles lead to far more organic aerosol particles forming in the atmosphere than do diesel-fueled vehicles, a report says (Geophys. Res. Lett., DOI: 10.1029/2011GL050718). Atmospheric aerosols are associated with a host of adverse health effects and also affect climate. Whereas primary organic aerosols are directly emitted into the air by a variety of natural and man-made sources, secondary organic aerosols (SOAs) form in the atmosphere from gaseous compounds. Understanding SOA origin is important for air quality modeling and control. A group led by Roya Bahreini, a scientist at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado, Boulder, studied SOAs in the Los Angeles Basin. Comparing weekday and weekend traffic emissions—diesel emissions are 54% lower on weekends, and gasoline emissions stay more constant—the researchers found that diesel exhaust accounts for only up to 20% of SOA formation from vehicles. Therefore, efforts to control SOA production will be more effective if they focus on gasoline-burning engines, the authors say.