The Clean Air Act of 1986 directed the Environmental Protection Agency to regulate air pollution from major sources of emissions.
One of those sources is the livestock industry. Animal waste releases harmful gases like hydrogen sulfide, ammonia and volatile organic compounds in large quantities, especially at concentrated animal feeding operations, or CAFOs, where thousands of animals live in enclosed barns.
However, the EPA doesn’t have a methodology for estimating how much of a pollutant any facility is emitting. The amount of pollution can vary widely based on the number and type of animals, how the waste is stored and environmental factors.
The EPA started the process of studying air emissions in 2005, with the goal of creating models that would help the agency enforce the Clean Air Act. Eighteen years later, the agency still hasn’t finished the models, called emissions estimating methodologies, for CAFOs.
RELATED STORY: 18 years and counting: EPA still has no method
for measuring CAFO air pollution
Here are seven key moments in the process:
2005: Following a call from the National Academy of Sciences to study air pollution from livestock operations, the EPA signs a deal with pork, dairy, poultry and egg industry groups to fund a large-scale study of emissions from CAFOs.
In exchange for volunteering as a participant in the study, the EPA agrees not to sue the nearly 14,000 CAFOs that sign the contract for certain violations of the Clean Air Act.
The study, called the National Air Emissions Monitoring Study, measures data for two continuous years from 25 CAFOs combined from the egg, poultry, dairy and swine sectors.
“The NAEMS is still the largest study of (animal feeding operation) air emissions, by far,” study director Albert Heber says.
Despite monitoring emissions at only 25 locations, nearly 14,000 CAFOs remain protected by the EPA’s agreement to this day.
2009: The EPA misses its deadline for publishing the EEMs.
The agency expects the NAEMS monitoring to wrap up by the end of 2007. Instead, the monitoring doesn’t start until 2007 due to the large scale of the study and the amount of training and coordination needed among researchers, Heber says. Monitoring at the last sites wraps up in 2010.
2012: Three years after its deadline for finalizing EEMs for CAFOs, the EPA publishes its first drafts using data collected from the NAEMS.
The drafts, which address volatile organic compounds, ammonia and hydrogen sulfide emissions from livestock operations, are sent to an EPA Science Advisory Board panel for peer review.
2013: A Science Advisory Board panel, composed of scientists from relevant disciplines, reviews the EEM drafts and sends several criticisms and recommendations to the EPA.
The panel repeatedly points out the limitations of the NAEMS data, and recommends that the drafts not be applied to CAFOs nationwide.
“The sample size was not large enough, to be honest,” says Dr. Viney Aneja, an agricultural air quality expert and professor at North Carolina State University, who served on an EPA Science Advisory Board panel that reviewed the first drafts.
After the EPA receives the critiques from the Science Advisory Board, progress on the EEMs grinds to a halt.
2017: A report by the EPA’s Office of Inspector General finds that a lack of resources and institutional knowledge of agricultural air emissions are key reasons for the delay, and urges the EPA to renew its efforts to develop the EEMs.
2020: The EPA publishes the first revised drafts of EEMs for CAFOs since receiving the criticisms from the Science Advisory Board.
The agency continues to roll out revised EEMs over the next two years.
Today: The EPA plans to publish final versions of the drafts later this year and open up the EEMs to stakeholder and public comment. The agency says it will finalize the EEMs by the end of the year — 14 years past its own deadline.
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