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United States Department of Agriculture

Agricultural Research Service

National Program 203: Air Quality
Component Definitions
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Particulate Emissions. This component addresses particulates regulated under the NAAQS, including fugitive dust in the PM-10 and PM-2.5 categories (10 micrometer and 2.5 micrometer, respectively). Dust emissions result from wind erosion, on-farm operations, agricultural industry, and smoke from agricultural burning. The research seeks to elucidate the biological, physical, and chemical mechanisms by which particulates are generated, how they are transported and suspended in the air and their patterns of movement and deposition. The research goal is to support development of technology to reduce or prevent agricultural particulate emissions.

Ammonia and Ammonium Emissions. The central regulatory issue is agriculturally-emitted ammonia as a major source of secondary, PM-2.5 particulates as a result of its interactions with other atmospheric compounds. The focus of this component is on understanding ammonia emissions and their role in forming secondary particulates, developing methods to measure emissions, establishing emission factors for various agricultural activities, and suppressing ammonia and ammonium emissions beyond farm boundaries.

Malodorous Compounds. Although not regulated, offensive odors from animal production operations are a major nuisance and may have health impacts. Basic and applied research will be done to identify odor-producing agents and to understand the biological and chemical processes that produce odors, emit them to the atmosphere, and govern their distribution and movement off-farm. This will permit the development of mitigating measures for application at the emitting source.

Ozone Impacts. High concentrations of ozone in the lower atmosphere result in reduction of crop yields by up to 20%. Carbon dioxide may have a mitigating effect on these losses. ARS research assesses the effects of ozone and the interaction of ozone and carbon dioxide upon crop production and searches for the basis for developing ozone-tolerant crop varieties.

Pesticides and Other Synthetic Organic Compounds. Volatilized pesticides are a complex of very fine liquid particulates and gaseous phase compounds, or may be attached to particulates from other agricultural or non-agricultural sources. The research objectives are to understand the biological, physical, and chemical mechanisms that influence pesticide volatilization and transport, to understand transport processes, to understand the impacts of deposition, and develop means to reduce emissions.

Last Modified: 10/28/2008