EPA publishes draft air emission models for dairy operations

The Environmental Protection Agency (EPA) on Nov. 19 published draft air emission models and emission factors for dairy, swine and poultry operations. These models come on the heels of preliminary draft models that were issued by the EPA in the summer of 2022, with the draft models originally expected to be released by mid-2023. The draft models estimate daily and annual air emissions of ammonia, hydrogen sulfide, volatile organic compounds, and particulate matter from barns, corrals, manure lagoons and basins on farms.

As many readers are aware, these models have been developed by using data gathered during the National Air Emissions Monitoring Study (NAEMS), a nationwide research project intended to gather air emission data from animal feeding operations. The research for NAEMS was funded by the EPA’s 2005 Air Compliance Agreement, which allowed participating animal feeding operations to pay a civil penalty in exchange for certain immunity from suit from the EPA for potential air emission violations.

NAEMS research began in 2007 and consisted of 25 monitoring sites (including dairy, swine and poultry (layer and broiler) operations) located in 10 states. Dairy operations in California, Indiana, New York, Texas, Washington and Wisconsin were part of the study. With EPA oversight, several universities conducted the NAEMS research, studying and measuring the emissions of ammonia, hydrogen sulfide, particulate matter and volatile organic compounds from barns and manure storage facilities at the selected locations for a two-year period.

The EPA had initially planned to begin publishing emission estimating methodologies by 2009; however, limits in

the NAEMS data and extensive feedback from the EPA’s Science Advisory Board, among other factors, caused long delays.

The models can be accessed here, and are available for a 90-day review period for review, which will end Feb. 17.

Once the models are finalized, the EPA plans for the models to be used by the animal feeding operations that participated in the 2005 Air Compliance Agreement (and likely other animal feeding operations), to self-determine if the estimated emissions trigger permitting requirements. It is worth noting that current legislation and rulemaking have exempted the reporting requirements under the Comprehensive Environmental Response, Compensation, and Liability Act and the Emergency Planning and Community Right-to-Know Act – the two current regulations that require reporting of the emissions studied by NAEMS.

Considering the track record of NAEMS, it is difficult to know how or when the EPA will actually start to implement the use of these models. In the meantime, the impacted ag industries will need to continue to be involved in providing comments and feedback regarding these draft models.