Editor’s note: Most livestock farming in industrialized countries takes place on large enclosed farms, known in the United States as Concentrated Animal Feeding Operations (CAFOs), that house hundreds or thousands of animals. Many environmental and public health groups say CAFOs are major air and water polluters and should be regulated more stringently. Farmers and trade organizations typically respond that CAFOS already are adequately regulated and do not threaten nearby communities or the environment.

On April 11, 2017, the U.S. Court of Appeals for the D.C. Circuit struck down a rule, issued by the Environmental Protection Agency in 2008, that exempted livestock farms from reporting hazardous air emissions from animal waste. Unless EPA appeals to the Supreme Court, these farms will have to report releases of substances such as ammonia and hydrogen sulfide starting later this year.

For perspective on this decision and CAFO regulation, we offer views from three scholars who were not involved in the recent court case.

Martin C. Heller

Senior Research Specialist, Center for Sustainable Systems, University of Michigan

Most CAFO air emissions come from one source: manure. CAFOs concentrate many animals together, and more manure in one place means more concentrated emissions, with greater potential for health and environmental impacts than on small farms.

As it breaks down, manure produces many substances that are regulated under the Clean Air Act, including ammonia, hydrogen sulfide, methane, nitrous oxide and volatile organic compounds. These pollutants have numerous harmful impacts.

For example, both ammonia and hydrogen sulfide can irritate the eyes, nose, throat and respiratory tract. Ammonia also contributes to acidification of soils and streams and particulate air pollution. Methane and nitrous oxide are potent greenhouse gases that contribute to climate change.

Methane is also produced from natural digestive processes in cows and sheep. And CAFOs generate particulate matter from bedding, feed, manure, feathers, animal skin cells and atmospheric reactions between other air pollutants.

Measuring and understanding these emissions isn’t easy, and a great deal of research and field studies have been done in the past two decades. As a 2003 National Research Council report noted, air emissions from CAFOs are affected by many factors, including climate and temperature, animal species and life cycle stage, and management options. Estimates of emissions generated for one farm may not translate readily to others.

Farmers have several options for mitigating air emissions. They can modify animals’ diets to reduce or suppress air pollutant generation from manure. There also are various techniques for handling, storing and treating manure. Devices called anaerobic digesters, which capture methane from manure to use as an energy source, can reduce air pollutants. According to EPA’s AgSTAR program, 259 digesters are currently operating on U.S. farms, mostly dairy farms.

Other manure treatment plants on farms have reduced ammonia in swine manure by up to 70 percent and greenhouse gases by up to 98 percent in demonstrations. Another approach is using biofilters to remove pollutants from air before it is vented from farm buildings.

However, none of these systems has been fully scaled up yet. In addition, almost all research has been conducted on enclosed building CAFOs. Very few studies have been done on beef cattle feed lots, which are typically open-air systems, making emission monitoring and reporting even more challenging.

In sum, there is no silver bullet solution. Most strategies will require farmers to make large capital investments, which can be a strain on already thin-margin enterprises.

J.B. Ruhl

Professor of Law; Director, Program on Law and Innovation; Co-director, Energy, Environment and Land Use Program, Vanderbilt University

The court decision in Waterkeeper Alliance v. EPA might appear to be a sharp rebuke to the Bush administration. In fact, however, this rule was “owned” equally by the Obama administration, and reflected a long bipartisan history of light environmental regulation of agriculture.

EPA initially proposed the rule in 2007 after studying air emissions from farm animal waste for several years. Other industries must report releases of hazardous chemicals under the Comprehensive Environmental Response, Compensation, and Liability Act and the Emergency Planning and Community Right to Know Act. However, EPA reasoned that the federal government probably would not do anything about releases from farms, so it exempted farms from having to report airborne releases of ammonia and other hazardous chemicals from animal waste. In response to public comments, the agency did require large CAFOs to report air emissions under EPCRA.

In 2009 environmental organizations challenged the rule in court. EPA asked the court to leave the rule in place while it reconsidered its provisions and made appropriate revisions. Five years later, after the agency did nothing, environmentalists reopened the litigation. EPA vigorously defended the rule, but the court concluded last month that the agency did not have authority to exempt farms from reporting their emissions. In short, this rule was proposed by a Republican president, defended by a Democratic president and lost by another Republican president.

It may seem surprising for elected officials from both parties to support such a hands-off approach. But the environmental law of agriculture has been riddled with exemptions, omissions, reductions and other “safe harbors” from regulation since the dawn of modern environmental law in the early 1970s.

If agriculture did not have serious environmental impacts, there would be good reason to regulate it lightly. But runoff from farms and ranches is the leading cause of water quality impairment in the United States. Farms produce significant air pollution in the form of dust, pesticides and other chemicals, and account for 9 percent of our nation’s greenhouse gas emissions. Farm pollution is underregulated because nearly every congressional district has an agricultural presence, and national farm lobbies fiercely oppose any form of environmental regulation.

Many farms are working to be more sustainable and to reduce their environmental footprints. But on the whole, farming in the United States causes a wide array of environmental injuries, yet is treated differently from all other polluting industries. The Waterkeeper Alliance decision is a rare instance of a court striking down one of agriculture’s many exemptions from environmental regulations.

Sacoby Wilson

Assistant Professor, Maryland Institute for Applied Environmental Health, University of Maryland-College Park

Individuals who live near CAFOs have higher exposure and health risks compared to people who live farther away. They may experience more episodes of respiratory irritation, acute or chronic asthma, mood disorder and immune suppression. Studies have shown high rates of asthma in children who attend schools near industrial hog farms.

CAFO siting also raises environmental justice concerns. One groundbreaking study analyzed the distribution of 2,500 hog CAFOs in North Carolina and found 7.2 times more CAFOs in areas with the highest poverty levels compared to lower levels. Hog CAFOs were five times more common in areas with the greatest percentage of nonwhite residents compared to areas with the lowest percentage.

North Carolina schools located close to hog CAFOs were found to have more low-income children and children of color than schools located farther away from hog CAFOs. A study in Mississippi also found higher concentrations of hog CAFOs in areas with more African-Americans and poor people. Now residents of Maryland’s Eastern Shore are concerned about siting of industrial poultry farms near poor people and people of color.

Recently several advocacy groups submitted a complaint to EPA’s Office of Civil Rights which asserted that permitting of CAFOs by the North Carolina Department of Environmental Quality was discriminatory and violated Title VI of the Civil Rights Act. In January 2017 EPA sent a 14-page letter of concern to North Carolina which validated the environmental justice concerns of residents who have been fighting against the industrial hog industry for decades.

CAFOs are classified as point sources under the Clean Water Act. CAFO owners must obtain permits to discharge wastewater into rivers, streams and other surface waters.

EPA has been egregiously derelict in not requiring these operations also to obtain permits under the Clean Air Act. The Waterkeeper decision is important because it will force CAFOs to adhere to EPA rules and regulations for monitoring and reporting emissions of pollutants covered by the National Ambient Air Quality Standards.

This decision could lead to more monitoring of CAFOs’ toxic air emissions. Obtaining such data will inform local health ordinances and zoning requirements.

Requiring CAFOs to report their readings on site would help validate fenceline monitoring and provide more site-specific data for assessing exposure-disease relationships. It also would empower residents by providing data to support lawsuits, including trespass and nuisance cases. And it would finally force this industry to recognize that it is an industry, not “family farming,” and must use control technologies similar to other pollution-emitting industries.

Sacoby Wilson received funding from the National Institutes of Health and the Environmental Protection Agency for graduate work on CAFOs in 1998-2003.

JB Ruhl and Martin C. Heller do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.