EPA says decades-old monitoring data are too limited to reliably develop emissions-estimating methods for U.S. livestock and poultry farms.
Thousands of U.S. livestock and poultry operations are getting closure on a federal air emissions initiative that began more than two decades ago.
The U.S. Environmental Protection Agency has announced it will not develop emissions estimating methodologies under the 2005 Animal Feeding Operations Consent Agreement and Final Order, commonly referred to as the 2005 Air Compliance Agreement.
EPA's enforcement office will also work to end obligations under the agreement.
The decision affects an initiative involving approximately "2,600 animal feeding operations (AFOs), representing nearly 14,000 farms or facilities", that joined the 2005 agreement.
For producers who have spent years waiting to learn what permitting or reporting implications might eventually result from the research, EPA's decision brings the project toward an end.
Why EPA is ending the effort
At the heart of EPA's decision is a straightforward issue: the agency concluded the underlying data are no longer adequate for the job.
The National Air Emissions Monitoring Study, or NAEMS, collected data between 2005 and 2007.
EPA studied emissions including ammonia, hydrogen sulfide, particulate matter and volatile organic compounds. The intent was to develop tools that participating animal feeding operations could use to estimate their emissions and help determine their regulatory responsibilities.
More than two decades later, EPA determined the data are too old and limited to reliably develop the intended emissions methodologies.
EPA said farms have changed significantly since the monitoring occurred, including changes to barns, herd sizes, operational practices and manure-management systems.
As a result, the agency will not finalize emissions estimating methodologies under the 2005 agreement.
"Good science requires good data, and these data are too old and too limited to support methods that farms could rely on," EPA Acting Assistant Administrator for the Office of Air and Radiation Abigale Tardif said in the agency's announcement.
Hog, poultry and dairy farms have been waiting for answers
The long-running process has been particularly relevant to livestock producers.
The 2005 agreement followed a National Academy of Sciences report calling for improved methods of estimating air emissions from animal feeding operations.
EPA subsequently offered producers an opportunity to enter a voluntary agreement and participate in funding the nationwide emissions monitoring study.
The work involved livestock sectors including **swine, broiler chickens, egg-laying hens and dairy cattle**.
Data from the monitoring program were intended to support development of methodologies that could help farms determine whether their emissions triggered certain regulatory responsibilities.
EPA developed draft emissions estimating methodologies for the participating sectors, and earlier drafts were reviewed by the agency's Science Advisory Board in 2013.
EPA tried updating the methodologies
The agency had not simply abandoned the research following the initial monitoring period.
In November 2024, EPA released updated draft methodologies for public comment.
After the comment period closed in August 2025, the agency identified limitations involving the age and representativeness of the original data, along with changes to standard farm practices and technologies that could not be addressed using the available information.
EPA's formal October 2026 determination says the considerable period since the original data collection and limitations within those data mean the study framework can no longer reliably serve its original purpose.
What changes for farmers?
EPA says ending the emissions methodology effort "does not change its implementation of the Clean Air Act" or its commitment to clean air, including in rural communities.
That distinction is important for producers.
The decision relates specifically to EPA's ability to develop the intended emissions estimating methodologies from the NAEMS data and the agency's plan to end obligations under the 2005 Air Compliance Agreement. It should not be interpreted as eliminating the Clean Air Act or EPA's broader environmental responsibilities.
EPA says it intends to notify, to the extent possible, the approximately 2,600 AFOs subject to the 2005 agreement and then terminate the agreement.
There have also been changes to other federal environmental reporting requirements since the agreement was established. EPA's formal determination notes that, because of subsequent legislation and rulemaking, reporting air emissions from animal waste at farms is not required under the Comprehensive Environmental Response, Compensation, and Liability Act, or CERCLA, or the Emergency Planning and Community Right-to-Know Act, known as EPCRA.
Farm air emissions research isn't necessarily over
While EPA is abandoning the effort to produce the methodologies from the old NAEMS dataset, the agency says it will continue working with the U.S. Department of Agriculture, land-grant universities and agricultural producers on practical and science-based approaches to understanding and reducing farm air emissions.
That may prove particularly important as production practices continue to evolve.
The challenge identified by EPA illustrates how quickly agricultural data can lose relevance when livestock housing, manure systems, technology and farm operating practices change.
For the thousands of farms connected to the 2005 agreement, however, EPA has made its decision: it concluded the existing NAEMS information cannot reliably support the emissions methodologies the agency originally intended to develop.