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Contribution of Small Engine Emissions to Ambient Air Pollution Concentrations
Scientific Problem and Policy Issues - Mobile sources are significant contributors to air pollution concentrations and exposures, especially in urban and suburban settings. Mobile sources contribute to ambient ozone, particulate matter, and air toxics concentrations. The mobile source emissions reported in the national inventories include both on-road and non-road mobile sources. The relative contribution of small non-road engines was a major gap in the emission inventories that has been addresses by ORD research.
Research Approach - The ORD performs research to characterize emissions from on-road and non-road mobile sources. A recent focus of this research program has been emissions from small non-road spark ignition engines. To accomplish this research a small engine dynamometer was used to measure emissions from sources such as lawn mowers, chain saws, leaf blowers, and string trimmers. The results of these emission tests have yielded the highest quality and most recent emissions data on non-road small engines and this data is a key component for the mobile source sector of the National Emission Inventory (NEI) developed by EPA’s Office of Air and Radiation (OAR). The small non-road emissions data has proven to be important because the current NEI indicates that the non-road small engine source sector is the second largest contributor to mobile source gaseous HAP and volatile organic compound (VOC) emissions behind light duty vehicles. The NEI is used by EPA and others to perform modeling analyses in support of policy decisions, exposure and risk assessments, and control strategy development and evaluation. For example, the NEI is used to run the Community Multiscale Air Quality (CMAQ) model in support of EPA policy analyses and NOAA air quality forecasting efforts and to run the ASPEN model as part of the National Air Toxics Assessment (NATA).
Results and Implications - ORD’s small engine emissions research has provided the highest quality and most recent data the EPA has on HAP emissions from small spark ignition engines. These data were critical in developing scientifically credible emission inventory estimates for the small non-road source sector of the NEI, which is the basis for modeling done with CMAQ and for the NATA. The results of these modeling efforts are a central component to EPA’s air program policies to protect public and the environment.
Research Collaboration and Publications
Baldauf, R. W., C Fortune, J. P. Weinstein, M. Wheeler, and F. Blanchard, Air Contaminant Exposure During the Operation of Lawn and Garden Equipment, JOURNAL OF EXPOSURE ANALYSIS AND ENVIRONMENTAL EPIDEMIOLOGY, Nature Publishing Group, 16(4):362-370 (2006)
Gabele, P. A. Characterization of Emissions from Hand-Held Two-Stroke Engines. Presented at 93rd Annual AWMA Conference, Salt Lake City, UT, June 18-22, 2000
Contact
Katherine Coutros
919/541-2433
coutros.katherine@epa.gov
National Exposure Research Laboratory (E205-03)
Research Triangle Park, NC 27711