Emission Factor for Free-stall Dairies

Improvements have been reported in the PM-10 emission factor for free-stall dairies that could significantly reduce the costs of compliance with air quality standards. With funding from NIFA, Texas A&M researchers reported that the correct PM-10 emission factor for free-stall dairies should be 5, with a range of 3 lb per 1,000 head per day, rather than 135, a number that one state was considering.

The researchers reported preliminary ammonia emission factors of 30 lb per 1,000 head per day. This emission factor is approximately 50 percent of the factor that has been used by some state air pollution regulatory agencies (SAPRAs).

This study is unique in that it is based on flux measurements from a number of different sources (free stall, open lot, lagoon, composting, etc.) and an emission factor based on a “weighted average” of the area sources. Work is continuing to gather data to confirm this preliminary emission factor for ammonia.

More information is available on the Center for Agricultural Air Quality Engineering and Science (CAAQES) Web site.

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