EPA Drops Livestock Emissions Models Built on 2005–07 NAEMS Data

The EPA will terminate a 2005 air-emissions agreement covering livestock operations, after concluding that the emissions models it developed from a 2005–07 monitoring study no longer reflect present-day production. The decision scraps estimation methods built on measurements from just 25 operations in ten states — and, for dairy specifically, on observations from as few as five farms.

The National Milk Producers Federation (NMPF) welcomed the announcement, describing it as a step towards clearer regulation for American dairy producers. Dairy farms and other livestock businesses that signed on to the National Air Emissions Monitoring Study (NAEMS) had waited more than two decades for a final outcome.

What did the 2005 agreement actually produce?

The agreement was established to produce scientifically credible ways of calculating emissions from animal feeding operations. Monitoring for NAEMS ran from 2005 through 2007 at 25 operations across ten states. Researchers gathered measurements of four pollutant categories: ammonia, hydrogen sulfide, particulate matter and volatile organic compounds. Those observations formed the dataset behind the emissions-estimation methods EPA subsequently developed.

That dataset is now the problem. EPA concluded the measurements were too dated and their coverage too limited to provide reliable estimates for today's livestock production. Changes to livestock housing, herd sizes, manure-handling approaches and on-farm technologies have all cut into the dataset's relevance, and the agency cited concerns about both the age of the observations and how well they represent the current industry.

Why did the dairy models fail technical review?

NMPF had already questioned the proposed models for estimating dairy emissions — and its technical review laid out specific failures:

• The dairy models depended on observations from just five dairy farms.
• Estimated emissions per cow varied substantially according to herd size.
• Some estimates turned negative when temperatures fell below freezing.
• The models gave limited weight to advances in animal feed and genetics, manure-handling practices and emissions-control technology.

A model that produces negative emissions below freezing is, by any engineering standard, broken. That defect alone gave the federation grounds to push back.

What happens next for covered operations?

EPA will contact the operations covered by the arrangement and carry out termination under the agreement's own provisions. Two things do not change: the agency's implementation of the Clean Air Act stays intact, and livestock businesses remain subject to other applicable environmental requirements.

On the science side, EPA plans further work with the US Department of Agriculture, land-grant universities and agricultural producers on practical, science-grounded approaches to understanding farm air emissions and reducing them. NMPF, for its part, said it will keep collaborating with government agencies, universities and dairy cooperatives to support environmental improvements across the dairy sector.

The milestone to watch now is the termination process itself: how EPA contacts and releases the 25 monitored operations, and whether a successor measurement program — with a modern dataset — gets funded to replace what 2005–07 produced.