Air Quality Issues and Animal Agriculture: A Primer
Prepared for Members and Committees of Congress
From an environmental quality standpoint, much of the public and policy interest in animal
agriculture has focused on impacts on water resources, because animal waste, if not properly
managed, can harm water quality through surface runoff, direct discharges, spills, and leaching
into soil and groundwater. A more recent issue is the contribution of emissions from animal
feeding operations (AFO), enterprises where animals are raised in confinement, to air pollution.
This report provides background on the latter issue.
AFOs can affect air quality through emissions of gases such as ammonia and hydrogen sulfide,
particulate matter, volatile organic compounds, hazardous air pollutants, and odor. These
pollutants and compounds have a number of environmental and human health effects.
Agricultural operations have been treated differently from other businesses under numerous
federal and state laws. Some environmental laws specifically exempt agriculture from regulatory
provisions, and some are designed so that farms escape most, if not all, of the regulatory impact.
The primary regulatory focus on environmental impacts has occurred under the Clean Water Act.
In addition, AFOs that emit large quantities of air pollutants may be subject to Clean Air Act
regulation. Some livestock operations also may be regulated under the release reporting
requirements of the Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA) and the Emergency Planning and Community Right-to-Know Act (EPCRA).
Questions about the applicability of these laws to livestock and poultry operations have been
controversial and have drawn congressional attention.
Enforcement of federal environmental laws requires accurate measurement of emissions to
determine whether regulated pollutants are emitted in quantities that exceed specified thresholds.
Two reports by the National Research Council evaluated the current scientific knowledge base
and approaches for estimating air emissions from AFOs as a guide for future management and
Stakeholders may find little agreement on these issues, with the exception of agreeing on a need
for research to estimate, measure, and characterize emissions, and to develop and evaluate
technologies to mitigate and control emissions.
In an effort to collect scientifically credible data on air emissions, in January 2005 the
Environmental Protection Agency (EPA) announced a plan negotiated with segments of the
animal agriculture industry. Called the Air Compliance Agreement, it is intended to produce air
quality monitoring data on AFO emissions, while at the same time protecting participants through
a “safe harbor” from liability under certain provisions of federal environmental laws. Issues
related to this agreement, which has been controversial among environmental advocates, state and
local air quality officials, and some industry groups, are discussed separately in CRS Report
RL32947, Air Quality Issues and Animal Agriculture: EPA’s Air Compliance Agreement,
coordinated by Claudia Copeland.
Introduc tion ..................................................................................................................................... 1
Air Emissions from Livestock and Poultry: Sources and Impacts..................................................2
Health and Environmental Impacts...........................................................................................2
Environmental Statutes and Regulation of Animal Feeding Operations.........................................6
Clean Water Act........................................................................................................................8
Clean Air Act.............................................................................................................................9
CAA Regulation in California..........................................................................................12
Other States’ Air Quality Regulatory Activities................................................................15
CERCLA and EPCRA.............................................................................................................17
Enforcement Against AFOs..............................................................................................18
National Research Council Reports on Air Emissions from AFOs...............................................21
The Role of USDA........................................................................................................................23
Figure 1. Fate and Transport of Air Emissions Associated with Animal Feeding
Operations .................................................................................................................................... 3
Table 1. Potential Importance of AFO Emissions at Different Spatial Scales.................................5
Table 2. CAA Classification of Substances in AFO Emissions.....................................................10
Author Contact Information..........................................................................................................26
Animal agriculture is a $100 billion per year industry in the United States. Livestock and poultry
are raised on an estimated 1.3 million farms throughout the nation. About 238,000 of these farms
are considered animal feeding operations (AFO)—agriculture enterprises where animals are kept
and raised in confinement. An estimated 95% of these are small businesses: most AFOs raise
fewer than 300 animals. Very large AFOs, housing 300 or more animals such as cows (or
equivalent numbers of other animal species), are defined as concentrated animal feeding
operations, or CAFOs. For more than two decades, organizational changes within the industry to
enhance economic efficiency have resulted in larger confined production facilities that often are
geographically concentrated. Increased facility size, greater numbers of animals being raised at
large feedlots, and regional concentration of livestock and poultry operations have, in turn, given
rise to concerns over the management of animal wastes from these facilities and potential impacts
on environmental quality.
From an environmental quality standpoint, much of the public and policy interest in animal
agriculture has focused on impacts on water resources, because animal waste, if not properly
managed, can adversely impact water quality through surface runoff and erosion, direct
discharges to surface waters, spills and other dry-weather discharges, and leaching into soil and
groundwater. However, animal feeding operations can also result in emissions to the air of
particles and gases such as ammonia, hydrogen sulfide, and volatile organic chemicals (VOC). At
issue today are questions about AFOs’ contribution to total air pollution and corresponding
ecological and possible public health effects. Resolving those questions is hindered by a lack of
adequate, accurate, scientifically credible data on air emissions from AFOs, data that are needed
to gauge possible adverse impacts and subsequent implementation of control measures.
This report provides background on these issues.1 It first reviews the types of air emissions from
livestock and poultry operations and their human health and environmental impacts. It then
discusses provisions of several federal laws concerned with environmental impacts, beginning
with the Clean Water Act, because protecting water resources has been the primary regulatory
focus regarding livestock and animal operations. The Environmental Protection Agency (EPA)
has authority to address AFO air emissions under several laws—the Clean Air Act; the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, or
Superfund); and the Emergency Planning and Community Right-to-Know Act (EPCRA)—which
are discussed next. Questions about the applicability of these laws to livestock and poultry
operations have been controversial in several arenas and have drawn congressional attention.
Studies by the National Research Council concerning air emissions are reviewed, as are relevant
activities of the states and the U.S. Department of Agriculture. Finally, the report identifies a
number of key research questions needed to characterize and evaluate animal agriculture
In January 2005, EPA announced a plan called the Air Compliance Agreement that would produce
air quality monitoring data on animal agriculture emissions from a small number of farms, while
1 This report focuses on the animal production segment of agriculture. Other types of production agriculture also can
generate air emissions, such as land preparation and crop harvest activities, prescribed burning, and other farming
practices, or emissions associated with storage and use of mobile source fuels and operation of farm vehicles, engines,
and equipment. While some of these types of emissions may contribute to air quality problems, especially in
agriculture-dominated regions, they are outside the scope of this report.
at the same time protecting all participants (including farms where no monitoring takes place)
through a “safe harbor” from liability under certain provisions of federal environmental laws.
Some industry sectors involved in negotiating this agreement, notably pork and egg producers,
strongly support it, but other industry groups that were not involved in the discussions have
concerns and reservations. State and local air quality officials and environmental groups oppose
the agreement. Issues related to the Air Compliance Agreement are discussed separately in CRS
Report RL32947, Air Quality Issues and Animal Agriculture: EPA’s Air Compliance Agreement,
coordinated by Claudia Copeland.
AFOs can affect air quality through emissions of gases (ammonia and hydrogen sulfide),
particulate matter (PM), volatile organic compounds (VOC), hazardous air pollutants,
microorganisms, and odor. AFOs also produce gases (carbon dioxide and methane) that are
associated with climate change. The generation rates of odor, manure, gases, particulates, and
other constituents vary with weather, time, animal species, type of housing, manure handling
system, feed type, and management system (storage, handling, and stabilization).
Emission sources include barns, feedlot surfaces, manure storage and treatment units, silage piles,
animal composting structures, and other smaller sources, but air emissions come mostly from the
microbial breakdown of manure stored in pits or lagoons and spread on fields. Each emission
source will have a different profile of substances emitted, with rates that fluctuate through the day
and the year. The sources, fate, and transport of AFO emissions are illustrated in Figure 1.
Pollutants associated with AFOs have a number of environmental and human health impacts.
Most of the concern with possible health effects focuses on ammonia, hydrogen sulfide, and
particulate matter, while major ecological effects are associated with ammonia, particulates, 2
methane, and oxides of nitrogen.
2 The following discussion is drawn primarily from National Research Council, Air Emissions from Animal Feeding
Operations, Current Knowledge, Future Needs, 2003, pp. 65-71 (hereafter cited as NRC 2003 AFO Report); and David
R. Schmidt et al., National Center for Manure and Animal Waste Management, North Carolina State University, Air
Quality and Emissions from Livestock and Poultry Production/Waste Management Systems, August 12, 2002.
Figure 1. Fate and Transport of Air Emissions
Associated with Animal Feeding Operations
Source: The University of Iowa and The University of Iowa Study Group, Iowa Concentrated Animal Feeding
Operations Air Quality Study, Final Report, 2002, p. 87.
The nitrogen in animal manure can be converted to ammonia (NH3) by a combination of
processes. Ammonia released from the surface of liquid manure storage structures rapidly adheres
to particles in the air, due to its cohesive properties, thus contributing to the formation of ambient
particulate matter, specifically ammonium nitrate and ammonium sulfate. These particles form to
a varying degree in the presence of ammonia and oxides of nitrogen or sulfur (see below). Once
emitted, ammonia also is re-deposited back to earth in rainfall that can harm surface waters and
aquatic life in lakes and streams. Ammonia aerosols in rainfall contribute to oxygen depletion of
aquatic systems and excessive growth of algae, as well as acidification of the environment. It is
estimated that emissions from animal waste account for about one-half of the total natural and
anthropogenic ammonia emitted in the United States annually. Ammonia has a strong, sharp,
characteristic odor that disperses rapidly in the air. Health effects at low concentrations include
eye, nose and throat irritation; exposure at very high short-term concentrations can be lethal.
Particles are highly complex in size, physical properties, and composition. For regulatory
purposes, airborne particulate matter (PM) is commonly considered as coarse particles (those less
than 10 microns in diameter, referred to as PM10), or fine particles, those less than 2.5 microns in
diameter (referred to as PM2.5). PM10 and PM2.5 can be directly emitted geologic material,
including from unpaved roads and other dust. Agriculture is a major direct source of PM10, from
sources such as grain mills or storage facilities, feeding equipment, and particles generated in
other mechanical processes. In contrast, PM2.5 is a different class of particles, resulting more from
evaporation and atmospheric chemical processes than from direct emissions. Fine particles are
formed in the atmosphere through the chemical interaction of precursor emissions such as sulfur
oxides, nitrogen oxides, and VOCs.
AFOs can contribute directly to particulate matter through several mechanisms, including animal
activity, animal housing ventilation units, and particles of mineral and organic material from soil
and manure that adhere to air molecules. As described above, particulate matter can contribute
indirectly to fine particle formation by emissions of ammonia, nitrogen oxides, and hydrogen
sulfide, which are converted to aerosols through reactions in the atmosphere. Particle formation is
highly dependent on atmospheric temperature, humidity, concentrations of the precursor
compounds, and other factors, so the particle formation is variable and difficult to predict.
Particles of differing sizes have been linked to health effects. Larger particles tend to be deposited
in the upper airways of the respiratory tract, whereas small particles have both health and
environmental effects: they can be deposited in the smallest airways in the lungs and, while still
airborne, also play an important role in formation of regional haze. Populations with long-term
exposure to heavier loads of particles have higher rates of mortality from major cardiovascular
diseases, as well as increased rates of morbidity. The primary environmental and ecological
effects of particles are related to haze and decreased visibility, which is caused by the suspended
aerosols that both absorb and scatter light.
Hydrogen sulfide (H2S) is a colorless gas with a strong and generally objectionable rotten egg
odor. It is produced in anaerobic (oxygen-deprived) environments from the microbial reduction of
sulfate in water and the decomposition of sulfur-containing organic matter in manure. Acute
human health effects include respiratory and cardiovascular irritation, as well as headaches. H2S
may have local effects of concern—especially odor—and may contribute to the atmospheric
sulfur burden of regions with a high density of AFOs, but few other sources.
Methane and nitrous oxide are known to contribute to global warming. An estimated one-half of
global methane comes from manmade sources, of which agriculture is the largest source, with
livestock production being a major component within the sector. EPA estimates that 25% of the
nation’s methane emissions come from livestock. Agricultural methane is produced by ruminant
animals, but also is emitted during microbial degradation of organic matter under anaerobic
conditions. Nitrous oxide forms via the microbial processes of nitrification and denitrification. In
the United States, animal waste accounts for about 6% of nitrous oxide emissions.
Many of the complaints about AFOs are generated by odor. Odor from AFOs is not caused by a
single substance, but is rather the result of a large number of contributing compounds, including
ammonia, VOCs, and hydrogen sulfide. As classes of compounds, odor and VOCs can be
considered together. VOCs (also referred to as reactive organic compounds, or ROG) vaporize
easily at room temperature and include a large number of constituents, such as volatile fatty acids,
sulfides, amines, alcohols, hydrocarbons, and halocarbons. In terms of their health and
environmental effects, some VOCs may irritate the skin, eyes, nose, and throat. They also can be
precursors to the formation of PM2.5 and ozone (smog).
Adverse effects of ozone include lung damage and exacerbated respiratory disease, as well as
diminished visibility. Ozone in the troposphere, the lowest layer of the atmosphere which is
closest to the Earth, has both natural and anthropogenic sources. It can damage forests, crops, and
manmade materials, and harm respiratory tissue through inhalation. Ozone that occurs naturally at
ground-level is generally at low concentrations that are not believed to threaten human health or
the environment. Ozone that is a byproduct of human activity is formed through the interaction of
sunlight with VOCs, nitrogen oxides, and other substances and adds to the total atmospheric
burden of the pollutant.
Effects of these pollutants occur on a variety of scales, as shown in Table 1.
Table 1. Potential Importance of AFO Emissions at Different Spatial Scales
Global, national, Local (property line or Primary effects of
Emissions and regional nearest dwelling) concern
NH3 (ammonia) Major Minor Atmospheric deposition,
N2O (nitrous oxide) Significant Insignificant Global climate change
NOx (the sum of nitric oxide Significant Minor Haze, atmospheric
and nitrogen dioxide) deposition, smog
CH4 (methane) Significant Insignificant Global climate change
VOCs (volatile organic Insignificant Minor Quality of human life
H2S (hydrogen sulfide) Insignificant Significant Quality of human life
PM10 (coarse particulate Insignificant Significant Haze
PM2.5 (fine particulate matter) Insignificant Significant Health, haze
Odor Insignificant Major Quality of human life
Source: National Research Council, Air Emissions from Animal Feeding Operations, Current Knowledge, Future Needs,
2003, Table ES-1, p. 5. Rank order from high to low importance is major, significant, minor, and insignificant.
Emissions from non-AFO sources may have different rankings. For example, VOCs and NOx play important roles in
the formation of tropospheric ozone, however, the role of AFOs is likely to be insignificant compared to other
Manure management varies widely across animal species, region, and farm type, depending on
climate, soil productivity, farm size, and other factors. Systems and strategies now in wide use by
farmers are those that have proved the most cost-effective and reliable at achieving their design
objectives. Land application has been and remains the predominant method for disposing of
manure and recycling its nutrient and organic content. For the most part, design objectives for
managing manure do not include minimization of emissions of ammonia, methane or other
gaseous compounds, but rather focus on odor and dust control, avoidance of direct discharge to 3
surface water, and land application at rates that are beneficial to growing crops.
As noted above, emissions of odors, gases, and dust from livestock production facilities arise
from buildings, manure storage, and land application. Eliminating emissions from one of these
sources will likely not eliminate emissions entirely, as control technologies often address only one 4
of the three sources. Many of the available technologies reduce emissions; none eliminates them.
Some technologies have been evaluated to the point of demonstrating efficacy, but most have not
been evaluated systematically.
Emissions from buildings can be reduced by inhibiting contaminant generation, or by capturing
and treating the air as it leaves the building (e.g., by using biofilters to treat ventilation air, or wet
3NRC 2003 AFO Report, pp. 46-47.
4 Iowa State University and The University of Iowa Study Group, Iowa Concentrated Animal Feeding Operations Air
Quality Study, Final Report, February 2002, p. 203. (Hereafter cited as Iowa CAFO Air Quality Study.)
or dry scrubbing of air as it passes through evaporative pads before release). Frequent manure
removal is one of the best ways of reducing contaminant generation within the building. Other
methods that can be used inside buildings include using bedded solid manure (i.e., manure mixed
with bedding that creates a solid stack of material), chemical additives on animal litter, and diet
There are four general types of manure storage: deep pits, outdoor slurry storage, anaerobic
lagoons, and solid stacks. Outdoor storage is the most apparent source of odors. Controls that
have been shown to be effective when managed properly include various types of covers
(permeable and impermeable, natural such as straw or cornstalks, and synthetic). Techniques to
manipulate the manure to minimize emissions also exist but have certain limitations. For
example, separating solids from liquid manure reduces the load on anaerobic lagoons, but also
creates a second waste stream to manage which may be detrimental to overall air quality. Proper
aeration will eliminate odors from outdoor storage, but it is expensive in a liquid system. 5
Anaerobic digesters reduce odors, but they are also not economically feasible.
Emission control during land application is best done by direct injection of liquid manure below
the soil surface. Solid manure is generally less odorous than liquid, but because it cannot be
injected, rapid incorporation into the soil by plowing or similar techniques is the best method to
While many treatment technologies are available that may be important in mitigating emissions,
the effectiveness of most of them is not well quantified. Extensive research programs are
underway in the United States and Europe, and many options of varying cost and effectiveness
are being evaluated. Livestock emission mitigation research is being performed by the University
of California at Davis, California State University Fresno, Purdue University, Texas A&M
University, and others, and information on available control measures and strategies for 6
agricultural sources of air pollution is being presented. Experts believe that cost, increased
management requirements, and a lack of economic or regulatory incentives to encourage or
require their use are the primary reasons that more poultry and livestock producers have not 7
adopted technologies to reduce emissions.
The animal sector of agriculture has undergone major changes in the last several decades, a fact
that has drawn the attention of policymakers and the public. In the United States there are an
estimated 238,000 animal feeding operations where livestock and poultry are confined, reared,
and fed, according to the U.S. Department of Agriculture’s 1997 Census of Agriculture.
5 Ibid., p. 207.
6 For example, the California Air Pollution Control Officers Association maintains a website to assist agricultural
operators, local air districts, and others with information on air pollution reduction techniques. See
7 Ibid., p. 209.
Organizational changes within the industry to enhance economic efficiency have resulted in larger 8
confined production facilities that often are geographically concentrated. The driving forces
behind structural change in livestock and poultry production are no different than those that affect 9
many other industries: technological innovation and economies of scale. From 1982 to 1997, the
total number of U.S. operations with confined livestock fell by 27%. At the same time, the
number of animals raised at large feedlots (generally confining 300 animals or more) increased by 10
88%, and the number of large feedlots increased by more than 50%. The traditional image of
small farms, located in isolated, rural locales, has given way to very large farming operations,
some on the scale of industrial activities. Increased facility size and regional concentration of
livestock and poultry operations have, in turn, given rise to concerns over the management of
animal wastes from these facilities and potential impacts on environmental quality.
Agricultural operations often have been treated differently from other types of businesses under
numerous federal and state laws. In the area of environmental policy, one observer noted that
agriculture is “virtually unregulated by the expansive body of environmental law that has 11
developed in the United States in the past 30 years.” Some laws specifically exempt agriculture
from regulatory provisions, and others are structured in such a way that farms escape most, if not
all, of the regulatory impact. The Clean Water Act (CWA), for example, expressly exempts most
agricultural operations from the law’s requirements, while under the Clean Air Act (CAA), most
agricultural sources escape that law’s regulatory programs because the majority of them do not
meet the CAA’s minimum emission quantity thresholds. Moreover, in implementing
environmental laws, federal and state regulators have traditionally focused most effort on
controlling the largest and most visible sources of pollution to the water, air, and land—factories,
waste treatment plants, motor vehicles—rather than smaller and more dispersed sources such as
Nevertheless, certain large animal feeding operations are subject to environmental regulation. The
primary regulatory focus on environmental impacts has been on protecting water resources and
has occurred under the Clean Water Act. In addition, facilities that emit large quantities of air
pollutants may be regulated under the Clean Air Act. Some livestock operations may also be
subject to the release reporting requirements of the Comprehensive Environmental Response,
Compensation, and Liability Act (the Superfund law) and the Emergency Planning and
Community Right-to-Know Act. The following sections describe relevant provisions of these
8 For additional information, see CRS Report RL33325, Livestock Marketing and Competition Issues, by Renée
Johnson and Geoffrey S. Becker.
9 Marc Ribaudo et. al, U.S. Department of Agriculture, Economic Research Service, Manure Management for Water
Quality: Costs to Animal Feeding Operations of Applying Manure Nutrients to Land, June 2003, Agricultural
Economic Report 824, 87 pp.
10 U.S. Department of Agriculture, Natural Resources Conservation Service, Manure Nutrients Relative to the Capacity
of Cropland and Pastureland to Assimilate Nutrients: Spatial and Temporal Trends for the United States, Publication
no. nps00-0579, December 2000, p. 18. (Hereafter cited as USDA 2000 Manure Nutrients report.)
11 J. B. Ruhl, “Farms, Their Environmental Harms, and Environmental Law,” Ecology Law Quarterly, vol. 27, no. 2
(2000), p. 265.
The Clean Water Act (CWA, 33 U.S.C. §§1251-1387) provides one exception to policies that
generally exempt agricultural activities—and specifically the livestock industry—from
environmental rules. The law protects water quality by a combination of ambient water quality 12
standards established by states, limits on effluent discharges, and permits. The regulatory
structure of the CWA distinguishes between point sources (e.g., manufacturing and other
industrial facilities which are regulated by discharge permits) and nonpoint sources (pollution that
occurs in conjunction with surface erosion of soil by water and surface runoff of rainfall or
snowmelt from diffuse areas such as farm and ranch land). Most agricultural activities are
considered to be nonpoint sources, since they do not discharge wastes from pipes, outfalls, or
similar conveyances. Pollution from nonpoint sources is generally governed by state water quality
planning provisions of the act.
However, the CWA defines large animal feeding operations that meet a specific regulatory
threshold number of animals (termed concentrated animal feeding operations (or CAFO); they are
a small percentage of all animal feeding operations) as point sources and treats CAFOs in a
manner similar to other industrial sources of pollution. They are subject to the act’s prohibition
against discharging pollutants into waters of the United States without a permit. In 2003, EPA
revised regulations that were first promulgated in the 1970s defining the term CAFO for purposes
of permit requirements and specifying effluent limitations on pollutant discharges from regulated
These regulations are intended to address the concern that animal waste, if not properly managed,
can adversely impact the environment through several possible pathways, including surface
runoff and erosion, direct discharges to surface waters, spills and other dry-weather discharges,
leaching into soil and groundwater, and releases to air (including subsequent deposition back to
land and surface waters). The primary pollutants associated with animal wastes are nutrients
(particularly nitrogen and phosphorus), organic matter, solids, pathogens, and odorous/volatile
compounds. Data collected for the EPA’s 2000 National Water Quality Inventory identify
agriculture as the leading contributor to water quality impairments in rivers and lakes. Animal
feeding operations are only a subset of the agriculture category, but 29 states specifically 13
identified animal feeding operations as contributing to water quality impairment.
The 2003 clean water rule applies to approximately 15,500 of the largest animal feeding
operations that confine cattle, dairy cows, swine, sheep, chickens, laying hens, and turkeys, or
about 6.5% of all animal confinement facilities in the United States. The rule details requirements
for permits, annual reports, and development of plans for handling manure and wastewater. The
rule contains a performance standard which prohibits discharges from regulated CAFOs except in
the event of wastewater or manure overflows or runoff from an exceptional 25-year, 24-hour
rainfall event. Parts of the rule are intended to control land application of animal manure and 14
wastewater. On October 31, 2008, EPA announced revisions to the 2003 rule, in response to a
12 For additional information on the Clean Water Act, see CRS Report RL30798, Environmental Laws: Summaries of
Major Statutes Administered by the Environmental Protection Agency (EPA), by Susan R. Fletcher et al.
13 U.S. Environmental Protection Agency, National Water Quality Inventory, 2000 Report, August 2002, EPA-841-R-
02-001, 1 vol.
14 For additional information, see CRS Report RL31851, Animal Waste and Water Quality: EPA Regulation of
Concentrated Animal Feeding Operations (CAFOs), by Claudia Copeland.
federal court ruling that had upheld major parts of the regulation, vacated other parts, and
remanded still other parts to EPA for clarification. EPA estimates that under the revised rule about
15,300 CAFOs (or 74% of the 20,700 CAFOs operating in 2008) will be required to obtain
permits. The revised rule also provides for greater public participation in connection with nutrient
management plans, requiring that they be subject to public notice and review and be included as
enforceable elements of a permit. Under the 2003 rule, CAFOs were to obtain permits by
February 2006 and to develop and implement nutrient management plans by December 2006.
Because of the time required to develop the revised rule, as a result of the federal court ruling,
EPA pushed back the deadlines for permits and nutrient plans to February 27, 2009. The
compliance deadline extension will not apply to new livestock operations or to existing CAFOs 15
that were required to obtain permits prior to the 2003 rule.
Scientists recognize that actions taken to mitigate harmful water quality impacts of managing
animal waste can have implications for air quality, in complex ways that are not perfectly
understood. Environmental policies do not always account for interactions between media. For
example, to meet water quality goals, lagoons are commonly used to store and treat manure waste
from swine and other operations. These storage systems volatilize nitrogen, thereby reducing its
concentration in lagoon effluent. But the volatilized nitrogen compounds escape into the air,
creating odors, contributing to fine particulates (haze), and potentially hastening global climate 16
The Clean Air Act (CAA, 42 U.S.C. §§7401-7671q) provides a complex and comprehensive 17
framework for regulating stationary and mobile sources of air pollution. The law emphasizes
controlling “major sources” that emit more than threshold quantities of regulated pollutants. Air
emissions from farms typically do not exceed the specified thresholds, thus they generally escape
most CAA regulatory programs. However, livestock producers and other agricultural sources are
not exempt from the statute, and for any whose emissions meet statutory or regulatory definitions
of “major,” provisions of the act could apply.
Under the CAA framework, EPA designates criteria air pollutants that may reasonably be
anticipated to endanger public health or welfare, and then establishes nationally uniform ambient 18
air quality standards for those pollutants (NAAQS). EPA has identified six criteria pollutants,
two of which (particulate matter and nitrogen dioxide) are directly associated with AFO
emissions. In addition, AFOs and other sources emit a number of substances (VOCs and nitrogen
oxide compounds) which are precursors of ozone, another criteria pollutant. The CAA also
regulates hazardous air pollutants (HAP). HAPs are identified in a statutory list that can be
modified by EPA regulation; EPA currently regulates 188 HAPs, including volatile organic
compounds (VOC) which are emitted by livestock facilities. Methanol, also known as methyl
15 For additional information, see CRS Report RL33656, Animal Waste and Water Quality: EPA’s Response to the
Waterkeeper Alliance Court Decision on Regulation of CAFOs, by Claudia Copeland.
16 Marcel Aillery, Noel Gollehon, Robert Johansson, Jonathan Kaplan, Nigel Key, Marc Ribaudo, Managing Manure to
Improve Air and Water Quality, U.S. Department of Agriculture, Economic Research Report 9, September 2005.
17 For additional information on the Clean Air Act, see CRS Report RL30798, Environmental Laws: Summaries of
Major Statutes Administered by the Environmental Protection Agency (EPA), by Susan R. Fletcher et al.
18 Under the act, EPA establishes primary ambient air quality standards at a level sufficient to protect the public health.
EPA also is authorized to establish secondary ambient air quality standards designed to protect the public welfare.
alcohol, is a listed HAP that is emitted from cows’ enteric emissions, freshly excreted manure,
and decomposing feed stored at dairies. Precursors of ozone (reactive VOCs) and PM2.5
(ammonia), both emitted by livestock facilities, are regulated air pollutants, even though they are
not listed as criteria pollutants or HAPs. (See Table 2.)
Table 2. CAA Classification of Substances in AFO Emissions
Substance Criteria pollutant Hazardous air pollutant Regulated air pollutant
Nitrogen oxides X X
Hydrogen sulfidec X
Source: National Research Council, Air Emissions From Animal Feeding Operations, Current Knowledge,
Future Needs, 2003, table 1-1, p. 16.
a. Ammonia is not a criteria pollutant but is a precursor for secondary PM2.5, which is a criteria pollutant.
b. Some but not all VOCs are listed as hazardous air pollutants. VOCs contribute to the formation of ozone, a
c. Hydrogen sulfide is not listed as a criteria pollutant or a hazardous air pollutant. However, it is a regulated
pollutant because it is listed as having a New Source Performance Standard which EPA establishes for
facilities that contribute significantly to air pollution.
d. Prior to 1987, particulate matter (PM) was a criteria pollutant and regulated as total suspended particulate
(TSP). Currently, the PM fractions listed as criteria pollutants are PM10 and PM2.5.
e. Odor is a regulated pollutant in some states.
States play an important role in carrying out CAA provisions and assuring that state air quality
meets federal air quality standards. The State Implementation Plan (SIP), prepared by the state (or
local) air pollution control agency, translates national ambient standards into emission limitations
and other control measures that govern individual sources of air pollution; the SIP is enforceable
as both state and federal law. The CAA details the basic content of SIPs: enforceable emission
limitations, other control measures, monitoring requirements, and schedules for compliance.
The provisions of the SIP govern individual facilities through two types of state permitting
programs. The preconstruction permit applies to major new sources or major modifications of an
existing source, and it describes proposed air pollution abatement systems, allowable emission
rates, and other requirements. In addition, most major stationary sources are required to obtain
operating permits that specify each source’s emission limitations and standards, compliance
schedule, reporting requirements, and other conditions. Major sources that emit HAPs also must
control those emissions to a level no less than the maximum achievable control technology
(MACT), as determined by EPA or state permitting authorities.
The CAA threshold determination of whether a source—including a livestock or poultry
operation—is subject to these requirements depends on whether it is defined as “major.” That
definition differs based on the region in which the source is located and whether that region is
attaining and maintaining national ambient air standards. The act classifies nonattainment areas
based on the extent to which the NAAQs is exceeded, and it specifically creates five classes of
ozone nonattainment (from least to most polluted: marginal, moderate, serious, severe, and
extreme). More stringent control requirements are imposed in areas with worse pollution.
Generally, a major source is a stationary source that emits, or has potential to emit, 100 tons per
year or more of any pollutant. However, regulated sources of HAPs that emit more than 10 tons
per year of an individual hazardous pollutant (or 25 tons per year of all HAPs combined), or
sources in the most serious nonattainment areas that emit as little as 10 tons per year of VOCs or
NOx, are defined as major sources and would be subject to these CAA requirements.
A state’s SIP provisions must be at least as stringent as federal requirements, but beyond the core
CAA framework, states have latitude in adopting requirements to achieve national ambient air
quality standards. States, for example, may regulate additional categories of sources or may
define major sources more stringently than do federal programs.
Most agricultural operations are believed to be minor sources of air pollution, and few have been
required to comply with the act’s permit requirements. Some environmental advocates have
argued that many large livestock facilities emit more than 100 tons per year of regulated
pollutants (especially ammonia) and should be regulated as major sources under federal law.
However, federal and state officials generally have placed a low priority on regulating agricultural
sources, and, further, a lack of adequate air quality monitoring data hampers the ability of
regulators to answer key questions. Agricultural air pollution has become more of an issue in
some parts of the country as EPA implements the 1997 NAAQS for particulates, which EPA 19
revised in September 2006, and as nonattainment areas look to reduce pollutants from more
sources as they strive to come into attainment. As discussed previously, emissions of ammonia
and several other AFO pollutants are precursors that transform in the atmosphere to form
secondary particulate matter. Aside from ammonia, other agriculture pollutants include dust that
contributes to PM10, diesel emissions from farm equipment, and emissions from specialized 20
activities such as crop burning.
A 2004 lawsuit brought in federal court by environmentalists argued that feedlots must be
regulated under the Clean Air Act and must obtain a CAA “permit to construct” under provisions
of the Idaho SIP. The company, intending to construct a large feedlot, had argued that the SIP did
not require a permit for key pollutants from agricultural sources, including ammonia and
hydrogen sulfide. In September 2004, the court ruled that the state’s plan did not allow such
exemptions, indicating that any agricultural facility in the state with sufficient emissions levels
would have to obtain a permit. The case was settled early in 2005 when the parties to the lawsuit
agreed to request that the Idaho Department of Environmental Quality conduct a rulemaking to
establish a process for CAA permitting of dairies in the state (Idaho Conservation League v.
Adrian Boer, D.Id.,Civ. No. 1:04-cv-00250-BLW, February 1, 2005). Industry officials say the
case has limited implications, because it refers specifically to the Idaho SIP, but environmentalists
involved in the case believe it could have significance nationally because of the mutual agreement
by the parties on emissions factors for ammonia that trigger CAA thresholds for dairies. In
response to this case, in June 2006 Idaho finalized a requirement that dairies and other CAFOs
19 For additional information, see CRS Report RL33254, Air Quality: EPA's 2006 Changes to the Particulate Matter
(PM) Standard, by Robert Esworthy and James E. McCarthy.
20 For additional information, see CRS Report 97-670, Agriculture and EPA’s New Air Quality Standards for Ozone
and Particulates, by James E. McCarthy and Jeffrey A. Zinn.
obtain air quality permits if they emit 100 tons or more of ammonia per year. The new rule makes
Idaho the first state to regulate ammonia emissions from CAFOs.
Other recent lawsuits have focused on methanol emissions from livestock operations (methanol is
a listed hazardous air pollutant under the CAA), seeking to require dairy operations to obtain
CAA permits and limit methanol emissions. Two pending cases are Association of Irritated
Residents vs. Fred Schakel Dairy (E.D. CA, No. 1:05-CV-00707) and Community Association for
the Restoration of the Environment v. DeRuyter Brothers Dairy (E.D. WA, Civil No. 08-3028-
In calculating emissions to determine major sources, fugitive emissions are not counted; however,
they do count for purposes of demonstrating attainment with NAAQS. Fugitive emissions are
defined in regulation as “those emissions which could not reasonably pass through a stack,
chimney, vent or other functionally equivalent opening” (40 CFR §51.165(a)(1)(ix)). EPA has
issued a number of interpretive memoranda and guidance documents discussing how fugitive
emissions should be accounted for in evaluating such industries as landfills, printing, and paint
manufacturing. No such guidance with respect to animal confinement systems has been issued,
but some groups, who believe that agricultural air pollution should be more vigorously controlled,
have in the past expressed concern that EPA might make a determination that emissions from
waste lagoons and barns are fugitive, thus excluding those types of AFO emissions from
applicable CAA requirements. In a 2003 letter to EPA, state and local air program administrators
said that such a policy, if pursued, would create inequities in CAA application between similar
operations in some sectors but not others.
Since barns and lagoons are the dominant sources of emissions from the CAFO industry,
such a policy would exempt most agricultural operations from many provisions of the Clean
Air Act. The result would be an evisceration of states’ and localities’ ability to address air 21
quality problems emanating from agricultural operations.
Some of the interest in agriculture’s impact on air quality derives from events in California and
that state’s progress in implementing the permit and SIP provisions of the Clean Air Act. The
state’s air pollution problems are diverse and, in some areas, severe. Throughout the state,
emission controls have become increasingly more stringent on currently regulated sources of air
pollution, such as factories and cars. State officials believe that, to meet state and federally
mandated requirements to improve air quality, emissions from all air pollution sources must be
reduced, whether they are large or small, industrial or agricultural.
Regarding agriculture, air quality improvement efforts have focused primarily on two regions
which represent California’s most challenging air quality problems for ozone and particulate
matter pollution. The South Coast (Los Angeles) Air Basin and the San Joaquin Valley Air Basin
are designated in extreme nonattainment for the federal health-based 1-hour standard for ozone.
In addition, the South Coast Basin and the San Joaquin Valley Basin are designated in severe and
serious nonattainment, respectively, for the more protective federal 8-hour ozone standard. In
21 Lloyd L. Eagan (President of State and Territorial Air Pollution Program Administrators) and Ellen Garvey
(President of Association of Local Air Pollution Control Officials), letter to Christine Todd Whitman (EPA
Administrator), April 7, 2003, p. 2.
these two areas, all sources of air pollution produce air quality impacts and have some level of
significance, and virtually all emission sources, even very small ones, are regulated. Both areas
have large concentrations of confined animal feeding operations; agriculture is the San Joaquin
Valley Basin’s most important industry and a significant source of its air emissions. Thus,
agricultural sources have been a particular focus of efforts to implement the federal and state laws 22
in both regions.
For more than 30 years, California law specifically exempted existing major livestock production
or equipment used in crop growing from all environmental permitting requirements. In 1994, EPA
notified the state that the agriculture exemption was a defect in the state’s clean air program that
prevented California from fully regulating all air pollution sources. That notification and
settlement of a lawsuit by citizen groups seeking to force EPA to impose air pollution controls on
California’s agriculture industry finally led EPA in October 2002 to withdraw federal approval of
the state’s program. Pursuant to the Clean Air Act, EPA was then required to implement a federal
program while the state addressed the cited deficiencies. Following that action, and during the
time it temporarily had responsibility for the California program, EPA evaluated ways to
administer the law, while minimizing significant new permitting requirements on thousands of
existing agricultural sources in the state. A major concern was recognition that there was
insufficient scientific information about agricultural air emissions to immediately issue permits to
sources or mandate pollution control requirements.
EPA considered various regulatory options, but did not actually issue any permits in California
before its responsibility for the state program ended in August 2003. The state re-assumed
responsibility after the legislature enacted a measure (California SB 700) that removed the long-
standing exemption for agriculture and set timelines for existing facilities to apply for clean air
permits and install control technologies. SB 700 regulates crop growers, dairies, poultry farms,
cattle ranches, food-processing operations, and other agriculture-related businesses in the state.
As of January 1, 2004, it made these sources subject to air quality permitting and specified
emission mitigation requirements. Deadlines and requirements differ, depending on the size of
facilities, level of emissions, and the attainment status of the region where the source is located.
The state and its local air quality management districts (in California, the state sets overall rules
and policies, and 35 local agencies have primary day-to-day responsibility) are now
implementing SB 700. The law mandated that the state Air Resources Board review scientific
information and adopt a definition of large confined animal facilities by July 2005; that
information is now being used by local air districts to begin issuing permits to facilities and
adopting various regulations to control emissions. Under SB 700, the district rules must require
facilities to obtain permits and to reduce emissions to the extent feasible. For severe and extreme
ozone nonattainment areas, the law requires best available retrofit control technology (BARCT).
In moderate and serious areas, regulated facilities will need to use reasonably available control
technology (RACT). In federal ozone attainment areas where air quality problems are less
significant, districts must adopt a rule requiring existing large confined animal facilities to reduce
air contaminants to the extent feasible unless the district makes a finding that such facilities will
not contribute to a violation of any state or federal standard. Regulated facilities were required to
prepare emission mitigation plans and comply with them by July 1, 2008.
22 Ten areas of the state have been designated in nonattainment for the one-hour federal ozone standard.
The definition of “regulated facility” developed by the state board seeks to include the majority of
emissions, or animals, which are in the larger livestock facilities in the state. By focusing on large
facilities and excluding smaller farms, dairies and other operations, the board expects to obtain
the most air quality benefit while regulating the fewest number of facilities. Under the approach
approved by the board in June 2005, agricultural operations in areas designated in nonattainment
for the federal 1-hour ozone standard will be defined as large confined animal facilities based on
specified numbers of animals at the facility (for example, facilities with 1,000 or more milk-
producing cows or 650,000 chickens at broiler chicken operations) and will be required to obtain
air quality permits. In areas with less significant air quality problems—those designated as in
attainment for the federal one-hour ozone standard—thresholds are twice as high (e.g., 2,000 23
milk-producing cows or 1.3 million broiler chickens). In addition, the state board is working
with local air districts, university researchers, and others to develop and evaluate research on
emissions factors from livestock operations to be used by facilities that are required to obtain air
permits. Affected industries are closely watching these research studies and the standards being
adopted by local air districts.
Even before the state board defined which existing facilities face new requirements, some local
air quality control districts had moved ahead with permitting and emission reduction
requirements. For example, the San Joaquin Valley district adopted rules to reduce PM emissions
from general crop-based agricultural operations and dairies with 500 or more cows, and in the
South Coast district, dairies with 50 or more cows are required to reduce emissions. Industry
contends that the state board should have first established how much pollution comes from
livestock operations before any permitting requirements were implemented, but the local districts
interpreted SB 700 as requiring permits by January 1, 2005. The local districts have attempted to
provide flexibility, but the overall situation has created substantial confusion for the farm
community in California. Districts also have adopted additional rules more recently. For example,
the San Joaquin Valley district adopted a rule in June 2006 to curb VOC emissions from dairies
and other CAFOs. Farmers in the state have resisted efforts to implement federal and state laws to
regulate emissions from agriculture. Some in industry contend that agriculture emissions are not
major sources of pollution and that any regulation should await completion of federal and state
studies that are examining the industry’s contribution to air pollution.
While California SB700 focuses on existing agricultural sources, by lifting the long-standing
exemption for such operations from the state Health & Safety Code, new and modified
agriculture sources in the state also became subject to permit and regulatory requirements of the
California State Implementation Plan (SIP). New or modified sources located in nonattainment
areas which may emit air pollution must obtain New Source Review permits that require
installation of best available control technology (BACT) and require purchase of “offsets” or
“emission reduction credits” from other sources in the same nonattainment area, in a relation
determined by the severity of the air pollution problem. Local district rules implement these
federal and state requirements. For example, San Joaquin Valley District Rule 2201 requires a
new or modified stationary source, including agriculture sources, to install BACT when the
potential to emit VOC exceeds 2 pounds per day and to purchase offsets for VOC when the
source’s potential to emit exceeds 10 tons per year.
23 State of California, California Environmental Protection Agency, Air Resources Board, Staff Report: Initial
Statement of Reasons for Rulemaking, Public Hearing to Consider the Large Confined Animal Facility Definition, May
6, 2005, 102 pp.
As agriculture operations continue to locate in areas of the state that already are highly
industrialized by agriculture, their compliance with these environmental requirements is being
scrutinized. For example, a large dairy under construction in Tulare County (San Joaquin Valley)
has been sued by local citizen groups for Clean Air Act violations stemming from constructing a 24
major stationary source without a New Source Review permit.
In terms of geographic impact, every state has agricultural operations in which animals are raised
in confinement, according to the U.S. Department of Agriculture. States with high livestock
populations, and with significant numbers of large operations (i.e., with more than 300 animal
units), include several West Coast, Southwest, and Northwest states (Washington, Oregon,
California and Arizona); the whole of the Midwest, from the Dakotas, Minnesota and Wisconsin
south through Texas; sweeping across the southeast to the coastal states of Georgia, the Carolinas, 25
Virginia, Maryland, and Pennsylvania; and north through New York and Vermont.
The issue of evaluating and managing the health and environmental impacts of emissions from
animal agriculture facilities has largely been left up to states. Air quality has not been the driving
force behind state government action on AFOs, but has emerged out of long-standing concern to
protect water resources. Several states have recognized a need to regulate air emissions from
agricultural operations, but many states have not yet directly adopted or enacted programs
affecting AFO emissions.
State programs, under statutes and regulations, both implement and supplement federal CAA
requirements. That is, in some cases, state programs have been adopted to ensure state
compliance with requirements of the federal law and to implement SIPs, such as facility permits
that apply to construction and operation of livestock operations. In other cases, states have
enacted more comprehensive laws and regulations calling for air emission testing and monitoring,
manure management to abate pollutant emissions, inspections, and testing. Some states have
regulatory programs or ambient air standards for odor and/or certain AFO pollutants, such as
hydrogen sulfide, for which no NAAQS apply. In states with significant animal production,
facility management statutes often govern construction and operation of AFOs, primarily for
purposes of protecting water quality, with incidental provisions for air quality. For example,
facility management statutes often contain setback requirements for confinement buildings and
waste impoundments that may help to reduce air emissions by avoiding or minimizing odor
A survey of seven states26 identified a number of measures to govern air emissions from livestock
facilities, but no comprehensive regulatory systems. States have used varied techniques to control
air emissions from AFOs. State programs set emission limits, require use of best management
practices, and impose other pre-operational and operational requirements. Hydrogen sulfide and
odor emissions from AFOs have received significant attention, but there is little or no
standardization of approach. For example:
24 Association of Irritated Residents, et al, v. Fred Schakel Dairy, E.D. Ca., No. 05-707, filed June 1, 2005.
25 USDA 2000 Manure Nutrients report, pp. 28-29.
26 Jody M. Endres and Margaret Rosso Grossman, “Air Emissions from Animal Feeding Operations: Can State Rules
Help?” Pennsylvania State Environmental Law Review, vol. 13, fall 2004, pp. 1-51.
• Minnesota requires feedlots and manure storage areas to acquire construction and
operating permits and also requires air emission plans for large livestock
facilities. The state has adopted an ambient air quality standard for hydrogen
sulfide which applies to emissions from AFOs as well as other sources.
• Iowa also has adopted a health effects-based ambient air quality standard for
hydrogen sulfide that will be used in a three-year AFO field study to measure
levels of H2S, ammonia and odor to determine if material adverse health effects
• Missouri regulations set odor emission limitations and require large AFOs to
submit odor control plans. In addition, the state’s CAA permit program includes
operational requirements for AFOs to prevent air pollution. Missouri’s CAA
contains a hydrogen sulfide emission standard that does not refer to AFOs or
other agricultural operations specifically, nor does it exempt AFOs. Missouri also
has an ambient acceptable level (AAL) for ammonia.
• In Texas, a consolidated program governs water and air quality general permits.
Its requirements control the emission of odors and other air contaminants from
AFOs, although its does not have a specific air emission threshold for odors. Like
Missouri, Texas has a hydrogen sulfide emission standard that makes no specific
reference to, or exception for, animal agriculture.
• Illinois has implemented a facility statute that relies in part on setback distances
to control odor emissions. Like Missouri, Illinois has established a numerical
“objectionable odor nuisance” standard (that is, when odor is detectable in
ambient air adjacent to residential or similar structures after dilution with a
specific volume of odor-free air) and has enforced the limitation against AFOs.
• Colorado water quality rules help to control air emissions through provisions that
govern the construction and operation of facilities that treat animal wastes. A
separate regulation establishes an odor emissions standard for swine feeding
operations and requires that anaerobic waste impoundments be covered.
• North Carolina, like Colorado, has focused its regulatory efforts on odor
emissions from swine operations. All AFOs must use management practices that
control odors, and some swine operations must submit odor management plans,
although it does not require control technology (e.g., covers) unless best
management practices fail. North Carolina does not have air emission standards
for H2S, ammonia, or odor.
A separate survey done by the Nebraska Department of Environmental Quality found that more
than half of the states have standards for hydrogen sulfide. States base standards on a variety of
issues, including odor or nuisance, welfare effects, and health effects. Consequently, standards
vary considerably from as low as 0.7 parts per billion (ppb) for a yearly average (New York) and
5 ppb averaged over 24 hours (Pennsylvania), to standards based on nuisance, such as
Minnesota’s 50 ppb not to be exceeded for one-half hour twice per year and measured at the AFO 27
27 Iowa CAFO Air Quality Study, p. 189.
Both the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA,
or Superfund, 42 U.S.C. §§9601-9675) and the Emergency Planning and Community Right-to-
Know Act (EPCRA, 42 U.S.C. §§11001-11050) have reporting requirements that are triggered
when specified quantities of certain substances are released to the environment, including 29
ambient air. Both laws utilize information disclosure in order to increase the information
available to the government and citizens about the sources and magnitude of chemical releases to
the environment. At issue today is how the reporting requirements and other provisions of these
laws apply to poultry and livestock operations.
Superfund authorizes programs to remediate uncontrolled or abandoned hazardous waste sites
and assigns liability for the associated costs of cleanup. Section 103(a) of CERCLA requires that
the person in charge of a facility (as defined in Section 101(9)) that releases a “reportable
quantity” of certain hazardous substances must provide notification of the release to the National
EPCRA establishes requirements for emergency planning and notification to communities about
storage and release of hazardous and toxic chemicals. Section 304(a)(1) of EPCRA requires the
owner or operator of a facility (as defined in Section 329(4)) to report to state and local
authorities any releases greater than the reportable quantity of substances deemed hazardous
under Superfund or extremely hazardous under EPCRA. Under Superfund, the term “release”
(Section 101(22)) includes discharges of substances to water and land and emissions to the air
from “spilling, leaking, pumping, pouring, emitting, emptying, discharging, injection, escaping,
leaching, dumping, or disposing into the environment.” Under EPCRA, the term “release”
(Section 329(8)) includes emitting any hazardous chemical or extremely hazardous substance into
the environment. Superfund excludes the “normal application of fertilizer” from the definition of
release, and EPCRA excludes from the definition of hazardous chemicals any substance “used in
routine agricultural operations or is a fertilizer held for sale by a retailer to the ultimate
The Superfund definition of “hazardous substance” (Section 101(14)) triggers reporting under
both laws. Among the reportable substances released by livestock facilities are hydrogen sulfide
and ammonia. The reportable quantity for both of these substances is 100 pounds per day, or 18.3
tons per year. Section 109 of Superfund and Section 325 of EPCRA authorize EPA to assess civil
penalties for failure to report releases of hazardous substances that equal or exceed their
reportable quantities (up to $27,500 per day under CERCLA and $27,500 per violation under
In addition to these reporting requirements, Superfund includes provisions authorizing federal
cleanup of releases of hazardous substances, pollutants, or contaminants that may present an
imminent and substantial danger to the public health or welfare (Section 104) and imposing strict
liability for cleanup and damages to natural resources from releases of hazardous substances
28 For additional information, see CRS Report RL33691, Animal Waste and Hazardous Substances: Current Laws and
Legislative Issues, by Claudia Copeland.
29 For additional information on CERCLA and EPCRA, see CRS Report RL30798, Environmental Laws: Summaries of
Major Statutes Administered by the Environmental Protection Agency (EPA), by Susan R. Fletcher et al.
(Section 107). The applicability of these provisions to animal agricultural sources and activities
has increasingly been receiving attention.
EPA has enforced the CERCLA/Superfund and EPCRA reporting requirements against AFO
release of hazardous air pollutants in two cases. The first involved the nation’s second largest
pork producer, Premium Standard Farms (PSF) and Continental Grain Company. In November
2001, EPA and the Department of Justice (DOJ) announced an agreement resolving numerous
claims against PSF concerning principally the Clean Water Act, but also the Clean Air Act,
CERCLA, and EPCRA. Among other actions under the settlement, PSF and Continental were to
monitor air emissions for PM, VOCs, H2S, and ammonia, and if monitoring levels exceed CAA
thresholds for any regulated pollutant, the companies would apply to the state of Missouri for any
necessary CAA permits. The companies also agreed to fund a $300,000 supplemental
environmental project (SEP) to reduce air emissions and odors from swine barns. In September
2006, DOJ announced settlement of claims against Seaboard Foods, a large pork producer with
more than 200 farms in Oklahoma, Kansas, Texas, and Colorado, and PIC USA, the former
owner and operator of several Oklahoma farms now operated by Seaboard. Like the earlier
Premium Standard Farms case, the government had brought complaints for violations of several
environmental laws, including failure to comply with the release reporting requirements of
CERCLA and EPCRA.
Both Superfund and EPCRA include citizen suit provisions that have been used to sue poultry
producers and swine operations for violations of the laws. In two cases, environmental advocates
claimed that AFO operators have failed to report ammonia emissions, putting them in violation of
CERCLA and EPCRA. In both cases, federal courts have supported broad interpretation of key
terms defining applicability of the laws’ reporting requirements (Sierra Club v. Seaboard Farms th
Inc., 387 F.3d 1167 (10 Cir. 2004) and Sierra Club v. Tyson Foods, Inc., 299 F.Supp. 2d 693
(W.D. Ky. 2003)).
EPA was not a party in either of these lawsuits. The U.S. Court of Appeals for the 10th Circuit
invited EPA to file an amicus brief in the Seaboard Farms case, in order to clarify the
government’s position on the issues, but EPA declined to do so within the timeframe specified by
Three other cases in federal courts, while not specifically dealing with reporting violations and air
emissions or what constitutes a “facility” for reporting purposes, also have attracted attention, in
part because they have raised the question of whether animal wastes that contain phosphorus are
hazardous substances that can create cleanup and natural resource damage liability under
Superfund. In 2003 a federal court in Oklahoma held that phosphorus contained in poultry litter in
the form of phosphate is a hazardous substance under CERCLA and thus could subject poultry
litter releases to provisions of that law (City of Tulsa v. Tyson Foods, Inc., 258 F. Supp. 2d 1263
(N.D. Okla. 2003)). This ruling was later vacated as part of a settlement agreement, but some
observers believe that the court’s reasoning may still be persuasive with other courts. The second
case, City of Waco v. Schouten (W.D. Tex., No. W-04-CA-118, filed April 29, 2004), a suit by the
city against 14 dairies alleging various causes of action based on disposal of wastes from those
operations, was resolved by a settlement agreement early in 2006.
The third case, State of Oklahoma v. Tyson Foods, Inc. (N.D. Okla, No. 4:05-cv-00329, filed June
claims based on the disposal of waste from 14 poultry operations in the Illinois River Watershed.
The state principally seeks its past and present response costs under CERCLA due to release of
wastes from these facilities and natural resource damages. The net result of these lawsuits is
growing concern by the agriculture community that other legal actions will be brought and that
the courts will continue to hold that the CERCLA and EPCRA reporting requirements and other
provisions apply to whole farm sites, thus potentially exposing more of these operations to
enforcement under federal law.
In 2005, a group of poultry producers petitioned EPA for an exemption from EPCRA and
CERCLA emergency release reporting requirements, arguing that releases from poultry growing
operations pose little or no risk to public health, while reporting imposes an undue burden on the 30
regulated community and government responders.
In December 2007, EPA issued a proposal in response to the poultry industry petition.31 EPA
proposed to exempt releases of hazardous substances to the air (typically during digestion or
decomposition) from animal waste at farms from the notification requirements of CERCLA and
EPCRA. The exemption would apply to releases to the air from manure, digestive emissions, and
urea, including animal waste mixed with bedding, compost, and other specified materials. “Farm”
is defined in the proposal as an agricultural operation from which $1,000 or more of agricultural
products are sold annually (the same definition used by the Department of Agriculture). EPA
explained that the rule is justified because of the resource burden to industry of complying with
reporting requirements, since the agency cannot foresee a situation where a response action would
be taken as a result of notification of releases of hazardous substances from animal waste at 32
The proposal drew significant public comment and response. While such a regulatory exemption
might satisfy many agriculture industry groups who seek a waiver or other means to limit
possible liability under CERCLA and EPCRA, environmental advocates and other interested
entities opposed the exemption, saying that emissions from animal wastes are not trivial or
benign. Critics noted that the EPA proposal would exempt releases of ammonia, as originally
requested in the industry petition, plus hydrogen sulfide and all other hazardous chemicals, such
as nitrous oxide and volatile organic compounds released from animal wastes. It also would apply
to all livestock operations, not just poultry farms. Some argued that an exemption is premature,
since EPA is moving forward with research on emissions levels, which could be undermined by a
regulatory exemption (see CRS Report RL32947, Air Quality Issues and Animal Agriculture:
EPA’s Air Compliance Agreement, coordinated by Claudia Copeland). State air quality officials
opposed a blanket regulatory or legislative exemptions, and they recommended that if the agency
30 In 1998, EPA granted an administrative exemption from release reporting requirements for certain radionuclide
releases. EPA cited authority in CERCLA Sections 102(a), 103, and 115 for granting administrative reporting
exemptions where “releases of hazardous substances that pose little or no risk or to which a Federal response is
infeasible or inappropriate.” See 63 Federal Register 13461 (March 19, 1998).
31 U.S. Environmental Protection Agency, “CERCLA/EPCRA Administration Reporting Exemption for Air Releases
of Hazardous Substances from Animal Waste,” 72 Federal Register 73700 (December 28, 2007).
32 Ibid., p. 73704.
considers any action, it should only be a narrow exemption, such as one based on a size threshold 33
In December 2008, EPA finalized the CERCLA/EPCRA administrative reporting exemption with 34
some modifications to the original proposal. The final rule exempts hazardous substance
releases that are emitted to the air from animal waste at farms from the notification requirement
of CERCLA. As proposed, the final rule relieves all livestock operations, not just poultry farms,
from CERCLA’s requirement to report hazardous substances releases to the air to federal
officials. In addition, the final rule provides a partial exemption for such releases from EPCRA’s
requirement to report releases to state and local emergency officials. Partially responding to some
public commenters, the final rule continues to apply EPCRA’s reporting requirement to large
CAFOs (those subject to Clean Water Act permitting, see page 8), but exempts smaller facilities.
A number of groups criticized the final rule, which a coalition of environmental advocates soon
challenged in federal court (Waterkeeper Alliance v. EPA, D.C. Cir., No. 09-1017, Jan. 15, 2009).
In September 2008, the Government Accountability Office (GAO) issued a report evaluating
EPA’s activities to regulate air emissions and water discharges from animal feeding operations.
GAO found that EPA is unable to assess the extent to which pollution from feedlots may be
impairing human health and the environment, because it lacks data on the amount of pollutants
that CAFOs are releasing to the air and water. GAO recommended that EPA develop a
comprehensive national inventory of CWA-permitted CAFOs and accelerate its efforts to develop
protocols for measuring and quantifying air contaminants from animal feedlots. GAO noted that
EPA has been criticized because its current air emissions monitoring activities are limited in
scope and sample size and may not produce sufficient information to shape future regulation.
Moreover, GAO questioned the basis for the CERCLA/EPCRA exemption that EPA proposed in
2007. “It is unclear how EPA made this determination when it has not yet completed its data
collection effort and does not yet know the extent to which animal feeding operations are emitting 35
Congressional interest in these issues has been apparent for some time. For example, in report
language accompanying EPA’s FY2006 appropriations, the House Appropriations Committee 36
urged EPA to clarify the reporting requirements of the two laws.
The Committee continues to be concerned that unclear regulations, conflicting court
decisions, and inadequate scientific information are creating confusion about the extent to
which reporting requirements in [CERCLA] and [EPCRA] cover emissions from poultry,
dairy, or livestock operations. Producers want to meet their environmental obligations but
need clarification from the Environmental Protection Agency on whether these laws apply to
33 National Association of Clean Air Agencies, letter to the Honorable Barbara Boxer, chairman, Senate Environment
and Public Works Committee, March 20, 2007.
34 U.S. Environmental Protection Agency, “CERCLA/EPCRA Administrative Reporting Exemption for Air Releases,”
73 Federal Register 76948-76960, December 18, 2008.
35 U.S. Government Accountability Office, “Concentrated Animal Feeding Operations, EPA Needs More Information
and a Clearly Defined Strategy to Protect Air and Water Quality from Pollutants of Concern,” September 2008, GAO-
08-944, p. 7.
36 U.S. Congress, House Committee on Appropriations, Report accompanying H.R. 2361, Department of the Interior,
Environment, and Related Agencies Appropriation Bill, 2006, H.Rept. 109-80, 109th Cong., 1st sess., p. 87.
their operations. The committee believes that an expeditious resolution of this matter is
Specific legislative proposals also have been discussed. In the 109th Congress, legislation was
introduced that would have amended CERCLA to clarify that manure is not a hazardous
substance, pollutant, or contaminant under Superfund and that the law’s notification requirements
would not apply to releases of manure (H.R. 4341). It was introduced the same day (November
15, 2005) that a House Energy and Commerce subcommittee held a hearing on animal agriculture
and Superfund. The Subcommittee on Environment and Hazardous Materials heard from
agriculture industry witnesses who urged Congress to provide policy direction on the issue that
has resulted from recent and potential litigation. Other witnesses testified that the reporting and
notification requirements of CERCLA and EPCRA provide a safety net of information, and that
other environmental laws, such as the Clean Air Act, cannot function in that manner. Related
legislation was introduced in the Senate (S. 3681). No further action occurred on either bill. th
Similar legislation was introduced in the 110 Congress (H.R. 1398 and S. 807), but again, no
further action occurred. (For additional discussion, see CRS Report RL33691, Animal Waste and
Hazardous Substances: Current Laws and Legislative Issues, by Claudia Copeland).
Some Members of Congress have been critical of EPA’s proposal to exempt routine animal waste
air releases from CERCLA and EPCRA’s reporting requirements, questioning the potential for 37
harmful environmental and enforcement impacts of the proposal. At a September 24, 2008, 38
hearing where GAO’s recent report was discussed, several House Energy and Commerce
subcommittee members said that they are skeptical of the EPA’s authority for a blanket
exemption. Others suggested that an exemption for small farms, whose emissions are unlikely to
cause environmental harm, would make sense. EPA and USDA witnesses supported the proposal,
saying that the air release waiver would only affect reporting meant for emergency response
situations, but would not affect requirements to report emissions of hazardous substances from
other farm sources, or releases of hazardous substances from manure into soil, ground water, or
During the time that EPA was developing the revised Clean Water Act CAFO rules that it
promulgated in 2003 (discussed above), the issue of air emissions from CAFOs received some
attention. The Clean Water Act requires EPA to consider non-water quality environmental
impacts, such as air emissions, when it sets effluent limitations and standards. EPA recognized
that certain animal waste management practices can either increase or decrease emissions of
ammonia and/or hydrogen sulfide and that some regulatory options intended to minimize water
discharges (such as anaerobic lagoons and waste storage ponds) have the potential to result in
higher air emissions than other options, due to volatilization of ammonia in the waste. Likewise,
emissions of nitrous oxide are liberated from land application of animal waste on cropland when
37 Letter from Reps. John Dingell, Albert Wynn, Hilda Solis to Stephen L. Johnson, EPA Administrator, March 18,
38 See http://energycommerce.house.gov/cmte_mtgs/110-ehm-hrg.092408.CERCLA.shtml.
nitrogen applied to the soil undergoes nitrification and denitrification.39 Some environmental
groups had urged EPA to address or restrict feedlot air emissions as part of the water quality rule.
In the proposed rule and the 2003 final revised rule, EPA generally evaluated air emissions
impacts of the rule, but it said that insufficient data exist to fully analyze all possible compounds
and the significance of air emissions from feedlot operations.
In part because of this lack of information, in 2001 EPA asked the National Research Council
(NRC) of the National Academy of Sciences for a report evaluating the current scientific
knowledge base and approaches for estimating air emissions from AFOs. EPA asked the NRC to
identify critical short- and long-term research needs and provide recommendations on the most
promising science-based approaches for estimating and measuring emissions. USDA joined EPA
in the request for the study. At the time, EPA was under a court order to issue the water quality
rules and hoped that the NRC report would help assure that rules aimed at improving water
quality would not have negative impacts on air emissions.
In an interim report released in 2002, the NRC responded to several of the EPA questions.40
Nitrogen emissions from production areas are substantial, the committee found, and control
strategies aimed at decreasing emissions should be designed and implemented now. It
recommended developing improved approaches to estimating and measuring emissions of key air
pollutants from AFOs and initiating long-term coordinated research by EPA and USDA with the
goal of eliminating release of undesirable air emissions. The committee said that implementation
of feasible management practices that are designed to decrease emissions, such as incorporating
manure into soil, should not be delayed while research on mitigation technologies proceeds. This
report focused particularly on the suitability of an approach for estimating air emissions from
AFOs presented in a 2001 draft EPA report. In that report, EPA attempted to develop a set of
model farms, based on manure management systems typically used by large AFOs, and identify
emissions factors that could be associated with each element of the model farm. In the absence of
actual data from extensive monitoring, EPA hoped that emission factors could be applied to 41
model farms to estimate annual mass emissions.
An emissions factor is a representative value that attempts to relate the quantity of a pollutant
released to the atmosphere with an activity associated with the release of the pollutant. The
emission factor approach is based on measuring emissions from a set of defined AFOs to obtain
an average emission per unit (per animal unit, or per production unit process, such as manure
storage piles and lagoons, stall areas, and feed storage areas), then multiplying the emission factor
by the number of units and period of time (e.g., annually). The current method of estimating cow,
chicken, swine, or any other livestock animal emissions is generally expressed in terms of
emissions per head, per year. Using this method, facility emissions are directly proportional to the
number of animals at the facility.
The NRC recognized that direct measurements of air emissions at all AFOS are not feasible.
However, it found that the model farm construct described by EPA cannot be supported because
39 Nitrification and denitrification are biological processes that, respectively, oxidize ammonia to nitric acid, nitrous
acid, or any nitrate or nitrite; and reduce nitrates or nitrites to nitrogen-containing gases.
40 National Research Council, The Scientific Basis for Estimating Air Emissions from Animal Feeding Operations,
Interim Report (Washington, DC: National Academies Press, 2002).
41 U.S. Environmental Protection Agency, Emissions from Animal Feeding Operations (Draft), EPA Contract No. 68-
D6-0011, Washington, DC, August 15, 2001, 414 pp.
of weaknesses in the data needed to implement it, which fail to consider variations in many
factors (geography, climate, management approaches) that could affect annual amounts and
temporal patterns of emissions from an individual AFO. Alternatively, the NRC recommended
that EPA consider a more complex process-based approach to focus on activities that determine
the movement of nutrients and other substances into, through, and out of each component of the
The NRC expanded on these recommendations in its final report, issued in 2003.42 Overall, it
found that scientifically sound protocols for measuring air concentrations, emission rates, and
fates are needed for the elements, compounds, and particulate matter associated with AFOs.
Similarly, standardized methodology for odor measurement should be developed in the United
States, the NRC said. The report noted that emission factor approaches should be broadened to
integrate animal and crop production systems both on and off the AFO (i.e., imported feeds and
exported manure) in order to represent the full environmental effects of animal production
systems. Such a systems analysis should include impacts of best management practices (BMPs)
aimed at mitigating AFO air emissions on other parts of the entire system.
The U.S. Department of Agriculture (USDA) manages a diverse range of programs involving
food, forests, rural development, agricultural trade, and conservation of natural resources. Several
USDA agencies have conservation responsibilities that may involve livestock and their
environmental effects. For example, the Natural Resources Conservation Service (NRCS)
provides technical assistance and information, as well as financial assistance, to landowners and
agricultural producers to implement conservation systems and practices, such as developing
Comprehensive Nutrient Management Plans to control AFO runoff.
The Agricultural Research Service (ARS) is the in-house research agency of USDA and conducts
a wide range of research activities. Among those related to livestock production are national
programs directed to air quality (focusing on particulates, agriculturally emitted ammonia, and
odor) and manure and by-product utilization (focusing on nutrient management and atmospheric
emissions). A second USDA agency is the Cooperative State Research, Education, and Extension
Service (CSREES). Like ARS, CSREES has projects related to livestock production, such as an
animal waste management program aimed at educating producers and increasing the use of best
management practices through training for AFO operators.
USDA cooperates with EPA when issues concern both agriculture and the environment. Notably,
the two collaborated on a Unified National Strategy for Animal Feeding Operations, issued in
1999, intended to minimize public health and environmental impacts of runoff from AFOs. That
strategy consisted of multiple elements and was based on a national performance expectation that
all AFO owners and operators would develop and implement site-specific Comprehensive
Nutrient Management Plans by 2009 to protect water quality and public health.
The importance of relationships between air quality and agriculture has received increased
recognition at USDA in recent years. One direct result was enactment of a provision in the 1996
Federal Agriculture Improvement and Reform Act (P.L. 104-127), the farm bill, requiring USDA
42 NRC 2003 AFO Report.
to create an Agricultural Air Quality Task Force. One finding in Section 391 of the statute stated
that USDA should lead efforts to determine accurate measures of agriculture’s role in air pollution
and in the development of cost-effective approaches to reduce pollution. Several provisions of the
2002 farm bill (the Farm Security and Rural Investment Act, P.L. 107-171) specifically addressed
air quality issues in the context of USDA conservation programs.
The Agricultural Air Quality Task Force is an advisor to the Secretary of Agriculture. Its chairman
is the chief of the NRCS, and its members represent USDA, EPA, industry, and basic and applied
science. It is charged with ensuring sound data quality and interpretation, so that policy
recommendations made by federal or state agencies to address air pollution problems related to
agriculture are based on accurate scientific findings, peer review, and economic feasibility.
In 2000, the task force issued a white paper on air quality and CAFOs. It recommended a
program of accelerated research, education, technology transfer, technical training, and financial
assistance to address CAFO air quality problems. According to the white paper, current funding
levels for air quality research are “elusive” and cannot be separately identified from all animal
waste-related research. It recommended that USDA and EPA develop enhanced long-term
funding packages and programs for agricultural air quality research and technology transfer that
specifically address CAFOs. The task force recommended that at least $12.8 million per year be
spent by USDA (NRCS, ARS, and CSREES) for coordinated, integrated research and technical 43
assistance programs for animal agriculture air quality. In FY2006, ARS supported four projects
to assess emissions from beef cattle feedlots, dairy operations and poultry operations and to
evaluate swine wastewater treatment systems. CSREES administers a National Research
Initiative on Air Quality which supports about a dozen projects on various topics intended to
better understand the environmental fate of agricultural atmospheric emissions, increase farm
adoption of best management practices to reduce agricultural emissions, and establish
scientifically sound emissions targets.
In debates over controversial and complex public policy questions, stakeholders who hold
differing perspectives at times may find little common ground. Sometimes the only point of
agreement is the need for more and better research to resolve key questions—and each side hopes
that research findings will support its own perspectives on the issues at hand. With regard to
questions about AFO emissions and the possible need to implement control strategies, there is
little dispute about the need for more research. Research on a wide range of topics currently is
being supported by federal agencies, a number of individual states, academic institutions, and
industry, but there is no apparent coordination or unified strategy. The monitoring study that EPA
proposes as part of the Air Compliance Agreement is intended to answer some questions.
However, in view of criticism of the study, doubts exist about the study’s utility. Some critics of
the Air Compliance Agreement fault EPA for planning only to measure emissions, but not also
using the monitoring study as an opportunity to research mitigation techniques.
43 USDA Agricultural Air Quality Task Force, Air Quality Research and Technology Transfer White Paper and
Recommendations for Concentrated Animal Feeding Operations, July 19, 2000. (Hereafter cited as AAQTF CAFO
In its 2003 report, the National Research Council addressed these issues and recommended
“substantial research efforts in both the short term and the long term.” Research in the short term
(four to five years), the NRC said, can significantly improve the capability of scientifically sound
modeling approaches for measuring and estimating air emissions, especially for process-based
modeling that the NRC recommends be developed by EPA and USDA. A long-term research
program (20-30 years) that encompasses overall impacts of animal production on the environment
can have substantial results in decreasing overall impacts on the environment, while sustaining
production at a high level. For the long term, coordinated research is needed to determine which
emissions are most harmful to the environment and human health and to develop technologies to 44
decrease their releases into the environment
Priority research needs identified by the NRC, USDA’s Agricultural Air Quality Task Force,45 and
others fall into two broad categories: fundamental research to estimate, measure, and characterize
emissions; and technology research (including technology transfer).
• Foremost is the need to produce scientifically sound, standardized methodology
as a basis for measuring and estimating gaseous and particulate emissions and
odor, from AFOs on local, regional, and national scales. The science for
estimating air emissions from individual AFOs should be strengthened, along
with models to understand the totality of AFO processes, including dispersion,
transformation, and deposition of emissions. This information is needed in order
to assess relationships between emissions, potential health indicators, and
candidate regulatory and management programs.
• A related concern is that much more needs to be understood about community-
level impacts from exposure to AFO emissions. Occupational health studies have
documented adverse health effects among AFO workers, such as acute and
chronic respiratory diseases, but experts agree that occupational health risks
cannot be extrapolated to community health risks. Peer reviewed studies of health
impacts on residents in the vicinity of livestock operations are limited. These
findings support a conclusion that AFO air emissions constitute a public health
hazard, deserving of public health precautions as well as larger, well controlled,
population-based studies to more fully ascertain adverse health outcomes and 46
their impact on community health.
• With regard to technology, there is a need to develop standardized measurement
technologies for pollutants and odorous compounds emitted by AFOs and
effective, practical, and economically feasible technologies to reduce and control
odors and pollutants. Experts believe that there is a need to develop and evaluate
innovative treatment processes for each of the major sources of AFO emissions,
confinement buildings, manure storage areas, and land application. Research
further should include programs to provide for transfer of economically viable
technologies to all producers.
In its 2003 report, the National Research Council observed that EPA and USDA have not devoted
the necessary technical or financial resources to estimate air emissions and develop mitigation
44 NRC 2003 AFO Report, pp. 11, 174-175.
45 AAQTF CAFO White Paper, p. 5.
46 Iowa CAFO Air Quality Study, p. 138.
technologies, and it criticized both for failing to address this deficiency in defining high-priority
research programs. The report said, “Each has pursued its regulatory and farm management
programs under the assumption that the best currently available information can be used to
implement its program goals.” It concluded that a change in research priorities in both agencies is 47
needed if air emissions are to be addressed with an adequate base of scientific information.
Congressional attention to the issues discussed in this report has been limited, with the result that
developments are proceeding largely by administrative and some judicial actions, not through
legislative policymaking. As described previously, one aspect that has attracted congressional
interest is questions about the applicability of CERCLA and EPCRA to livestock and poultry
operations. That interest has been apparent in the context of appropriations legislation and, more
recently, in legislation to amend CERCLA to clarify that manure is not a hazardous substance th
(H.R. 4341 and S. 3681 in the 109 Congress; similar legislation—H.R. 1398 and S. 807—was th
introduced in the 110 Congress; none of these bills has seen further action). A House
subcommittee held a hearing on these issues in November 2005 and another, discussed above, in
September 2008. Finally, there appears to be wide agreement among stakeholder groups on the
need for more research on a large number of related issues, but congressional interest in
supporting or funding more federal participation in research activities is unclear.
Specialist in Resources and Environmental Policy
47 NRC 2003 AFO Report, pp. 13, 153.