AGRICULTURE AND EPAS PROPOSED AIR QUALITY STANDARDS FOR OZONE AND PARTICULATES
CRS Report for Congress
Agriculture and EPA’s New Air Quality
Standards for Ozone and Particulates
Updated March 24, 1998
James E. McCarthy and Jeffrey A. Zinn
Senior Analysts in Environmental and Natural Resources Policy
Environment and Natural Resources Policy Division
Congressional Research Service ˜ The Library of Congress
This report discusses potential impacts on agriculture of the new air quality standards for
ozone and particulates promulgated by EPA on July 18, 1997. Legislation has been
introduced in both the House and Senate (H.R. 1984 / S. 1084) to block implementation of
the new standards, and the Senate has approved an amendment to the surface transportation
bill, S.Amdt. 1687, to address a limited set of implementation issues. At the request of
agricultural interests, the amendment includes a requirement that EPA report to Congress
on the ability of its sampling and analysis methods to differentiate types of fine particles.
This report will not be updated. For current information on implementation of the clean air
standards and related legislation, see CRS Issue Brief 97007, Clean Air Act Issues.
Agriculture and EPA’s New Air Quality Standards for Ozone
On July 18, 1997, the Environmental Protection Agency promulgated revisions
of the National Ambient Air Quality Standards for ground-level ozone and
particulates. EPA's action has elevated awareness of possible relationships between
agriculture and air quality in the agricultural community. Many in agriculture,
including the Department of Agriculture's Agricultural Air Quality Task Force, have
questioned the scientific basis for the new standards. The issues raised also have
been aired at congressional oversight hearings. This report summarizes these issues.
In assessing the potential impact of the new standards on agriculture, it is
important to note that EPA has promulgated new or revised standards for three
different pollutants: 1) ozone; 2) the relatively coarse particulate matter already
regulated (PM10); and 3) a new category, fine particulates (PM2.5). The potential
costs and impacts of each of these standards is different.
Agricultural production is adversely affected by ozone in the atmosphere, so
agriculture should benefit from a strengthening of the ozone standard. EPA estimates
these benefits at $1 billion annually. The agricultural community agrees that
lowering ozone concentrations will improve yields, while not necessarily agreeing
with the EPA estimate. The vast majority of the emissions that form ozone (nitrogen
oxides and volatile organic compounds) originate in urban and industrial areas.
Agricultural sources of these emissions would not likely be directly targeted by
measures implementing the new rule, although regulation of fuels and motor vehicles
might have indirect impacts on the agricultural sector.
The second standard being revised -- that for PM10, a category that includes
fugitive dust from construction or tilling the soil -- is effectively relaxed under EPA’s
proposal. The net effect would be that 31 of the 41 counties currently designated
nonattainment (many of them rural) would be reclassified to attainment. This would
benefit agriculture, by eliminating the need for additional controls in those areas.
The third standard, for PM2.5, has been the focus of agriculture’s concerns. EPA
states that fine particulates include five categories of pollutants, two of which can
come from agricultural sources. EPA denies any intention to regulate agricultural
sources of these emissions, which are not well-characterized, and in the Agency’s
view are less significant than emissions from power plants and transportation. But
agricultural interests have not been satisfied by EPA’s response, and, in any event,
regulatory decisions will be made by the states, not EPA.
Legislation has been introduced in both the House and Senate (H.R. 1984 / S.
1084) to block implementation of the new standards. Markup of these bills has not
been scheduled. On March 4, 1998, however, the Senate approved S.Amdt. 1687,
to address a limited set of implementation issues. At the request of agricultural
interests, the amendment includes a requirement that EPA report to Congress on the
ability of its sampling and analysis methods to differentiate types of PM2.5 particles.
Revisions of the Ozone and Particulate Standards....................1
Air Quality and the U.S. Department of Agriculture...................4
The Ozone and Particulate Issues.................................4
Regulatory Impacts Specific to Agriculture......................7
List of Tables
Table 1. Sources of PM2.5 Emissions, 1990.............................11
Agriculture and EPA’s New Air Quality
Standards for Ozone and Particulates
Revisions of the Ozone and Particulate Standards
On July 18, 1997, the Environmental Protection Agency promulgated revisions
of the National Ambient Air Quality Standards (NAAQS) for ground-level ozone and
particulates. The revisions are the result of a statutory requirement: in Section 109,
the Clean Air Act requires that EPA conduct a thorough review of the NAAQS at
five year intervals and “make such revisions ... as may be appropriate.” In the case
of particulates, the standard had been most recently reviewed in 1987. The American
Lung Association sued EPA over its failure to act within the required time period; in
a consent agreement, EPA has agreed to promulgate standards by July 19, 1997.
The ozone standard was not subject to the court deadline, but was the focus of
an earlier suit which EPA settled by reaffirming existing standards in February 1993
and promising to expedite its next review. The Agency subsequently placed its
review and promulgation of new standards for ozone on the same schedule as that for
particulates, on the grounds that the two standards would require controlling many
of the same sources of emissions.
The new ozone standard is 0.08 ppm averaged over an 8-hour period, as
opposed to 0.12 ppm averaged over a one-hour period. The particulate standard was
changed in several ways: the previous standard for particles smaller than 10 microns
(PM10) was relaxed as a result of new averaging methods and additional allowed
exceedances; but finer particles, less than 2.5 microns in diameter (referred to as
PM2.5), are to be separately regulated for the first time.
In setting and revising the National Ambient Air Quality Standards, the Clean
Air Act directs the EPA Administrator to protect public health with an adequate
margin of safety. This language has been interpreted, both by the Agency and by the
courts, as requiring standards based on a review of the health impacts, without1
consideration of the costs, technological feasibility, or other non-health criteria. In
developing these specific proposals, the Agency reviewed more than 270 studies of2
health effects over a 3-year period before proposing standards.
The net impact of both the ozone and PM2.5 standards will be increased
stringency. Analyses by interested parties, as well as EPA, indicate that many areas
1Lead Industries Association v. EPA, 647 F. 2d 1130 (D.C. Cir. 1980).
2For a detailed discussion of the studies reviewed, see 61 FR 65641 and 65719, December
13, 1996, or consult EPA’s home page for the standards at
considered to be in compliance with the previous NAAQS will not meet the new
standards. Under the PM2.5 standard, EPA estimated that about 170 U.S. counties
would not meet the standard versus 41 under the old PM10 requirement.3 For ozone,
the number of counties out of attainment under the proposed standard was estimated
to nearly triple, from 106 to about 280.4
Such an increase in the number of nonattainment areas and new methods of
measuring air quality could have broad implications for EPA, the states, and affected
industries, including agriculture. But the effects would not be immediate. A number
of steps will be necessary before the new standards can be implemented. In general,
EPA concludes that it will be 5-8 years before any regulatory decisions affecting
industry or other economic sectors are implemented by the states based on the revised
ozone standard, and 10-12 years before regulations are promulgated by states
implementing the PM2.5 standard. Lawsuits challenging the standards or the
measures adopted for implementation could cause further delay. During the interim,
new scientific reviews can be anticipated.
The 5-8 year delay for implementing controls under the ozone standard results
from the steps mandated by law for implementation of a new standard. Under
Section 107 of the Clean Air Act, Governors must submit a list of areas not attaining
a National Ambient Air Quality Standard within one year of its promulgation. EPA
reviews the information submitted and officially designates nonattainment areas
within 2 years of promulgating the standard.
At the time of designation, EPA is required by Section 172(a) of the Act to set
a date by which each area shall achieve attainment. The date may be 5 years or 10
years following the date on which an area is officially designated. The 10-year date
may also be extended for two additional one-year periods. Thus, areas newly
designated as nonattainment under the ozone standard will have 7-14 years after
promulgation of the ozone standard (i.e., July 2004 - July 2011) to attain it.
Actual control measures to be implemented in the states are decided by the
individual states, using guidance provided by EPA. Following the official
designation of nonattainment areas (July 1999), states are given 3 years to develop
a State Implementation Plan (SIP) identifying the control measures that will be
adopted to bring the areas into attainment. Following submission of these plans,
EPA has 6 months to determine whether the submission is complete and an
additional 12 months to approve, conditionally approve, partially approve, or
disapprove a state’s plan. Thus, if all deadlines are met, it would be January 2004
(6 ½ years following promulgation of a new standard) before there is an approved
implementation plan outlining the measures a state will take to attain the standard.
The PM2.5 standard will take 5 years longer to implement than the ozone
standard, for two reasons. First, there is at present no monitoring network in place
3Due to a lack of monitoring data for the specified pollutant, the estimate is necessarily only
a rough approximation. See http://22.214.171.124/naaqspro/pmlist.htm, for a list of the
4For a list of counties, see http://126.96.36.199/naaqspro/o3list.htm.
to determine which areas are nonattainment. Establishing this network is expected
to take at least 2 years. Second, attainment determinations are based on the results
of 3 years of monitoring. Thus, 5 years need to be added to the front of the process
described for ozone before Governors will submit lists of nonattainment areas to
EPA, and the State Implementation Planning process for PM2.5 begins. Barring
delays, nonattainment areas would be designated by July 2004, with attainment
deadlines in 2009-2016. The statutory deadline for SIPs identifying specific control
measures would be January 2009, if the earlier deadlines outlined here are met.
These dates will be modified if an amendment to the surface transportation bill
(S. 1173), approved by the Senate in March 1998, is enacted. The amendment
(S.Amdt. 1687), sponsored by Senator Inhofe, would give Governors until July 1999
to submit designations of ozone nonattainment areas, with final designation by the
EPA Administrator in July 2000. This would add one year to the ozone
implementation schedule outlined above.
Regarding PM2.5, the legislation sets December 31, 1999, as the deadline for
EPA to establish a monitoring network, requires Governors to submit lists of
nonattainment areas one year after the receipt of three years of monitoring data
(presumably December 31, 2004), and sets a December 31, 2005 deadline for EPA
to designate nonattainment areas. Under this timetable, the statutory deadline for
SIPs outlining control measures would be June 30, 2010, with attainment deadlines
stretching to the end of 2017.
This paper looks at the question of agricultural impacts from more stringent
ozone and fine particle standards. A subcommittee of USDA’s Agricultural Air
Quality Task Force, created by the 1996 Farm Bill, drafted comments on the
proposed rules during its initial meeting in March, 1997. Excerpts from these
comments were widely circulated in the farm press and in other places. Among other
things, the Task Force questioned the lack of information on incremental benefits and
costs associated with attaining the proposed standard, called for improved monitoring
capability for PM2.5, requested a more complete assessment of precursors to both
ozone and PM2.5, suggested that EPA look at key differences between rural areas and
urban areas where much of the data have been collected, asked EPA to consider the
special needs of smaller and less successful farmers, and recommended that the EPA
analysis be based on a fuller understanding of soil erosion problems and solutions.
Agriculture’s views on possible effects have been discussed at several hearings.
The House Agriculture Committee’s Subcommittee on Forestry, Resource
Conservation and Research held hearings on April 23 and September 16, 1997. The
Senate Agriculture Committee held a hearing July 22, 1997. In addition, at an April
Subcommittee on Clean, Air, Wetlands, Private Property and Nuclear Waste, three
panelists addressed agricultural topics; agricultural topics were also discussed at a
July 24, 1997 Environment Committee hearing. The comments offered at these
hearings, comments by USDA’s Agricultural Air Quality Task Force, and
information concerning agriculture provided in EPA’s analysis of the proposals were
the major sources of information used in preparing this report. We begin, however,
with some background concerning the Department of Agriculture and its experience
with air quality issues.
Air Quality and the U.S. Department of Agriculture
Air quality emerged only recently as a priority environmental topic in
agricultural policy and at USDA. For example, a 1989 national assessment of
resource conditions and concerns on the country’s privately-owned lands published
by USDA included lengthy and detailed discussions of soil and water quality, but
only brief treatment of three air quality issues; atmospheric deposition (more
commonly called acid rain), ozone, and wind erosion. The focus of the acid rain and
ozone discussions was on what is known about relationships between each topic and
agriculture, and centered on research. The wind erosion discussion explained why
air pollution was one of the resulting problems.
Since then, the importance of relationships between air quality and agriculture
has received increased recognition. This recognition culminated in enactment of
provisions in Section 391 of the 1996 Federal Agriculture Improvement and Reform
Act, better known as the 1996 Farm Bill, requiring USDA to create an Agricultural
Air Quality Task Force.5 One finding in the statute states that studies alleging that
agriculture is a source of particulates have been based on erroneous data, and 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.
The Task Force, is an advisor to the Secretary, and focuses on research, with
emphasis on data quality and interagency coordination.
Members of the Task Force, selected in January 1997, are experts who represent
USDA, industry, and basic and applied science. The law specifies that the Chief of
the Natural Resources Conservation Service serves as its chair. At its first meeting
in early March, 1997, the Task Force decided to pursue developing a Memorandum
of Understanding with EPA.6 Topics the Task Force is addressing include
greenhouse gas emissions and climate change, volatile organic compounds and
ammonia associated with livestock waste, and odor and visibility questions that arise
where agriculture is near residential and other land uses.7 For example, a
subcommittee of the Task Force will make recommendations to the whole group on
prescribed burning, to assist EPA as it develops policy proposals on the topic. The
Task Force met three times during its first year.
The Ozone and Particulate Issues
The issues raised by revision of the ozone and particulate standards can be
grouped in at least three categories: the adequacy of the science underpinning the
standards; questions regarding implementation; and regulatory impacts, including the
5P.L. 104-127, enacted April 4, 1996. Prior to the creation of this Task Force, there was no
official interagency mechanism within USDA to coordinate air quality topics.
6The goal of the MOU, signed in February 1998, is "to provide a thoughtful process for
involving the agriculture community and the environmental regulation community relative
to agriculture air quality."
7The minutes of the meeting are posted on the Internet at
costs and benefits of the proposals. Only the last of these has any unique agricultural
component; nevertheless, because of EPA’s mandate under the Clean Air Act, the
costs and benefits to agriculture (or any other sector of the economy) did not play a
central role in shaping the proposals.
Scientific Underpinnings. Questions concerning the scientific underpinnings
of EPA’s proposal have assumed a predominant role in the debate. EPA estimates
that fine particles cause 40,000 deaths per year, and that the proposed standard will
reduce this mortality by 15,000 lives annually. The ozone standards’ projected
effects are less dramatic: EPA estimates that implementation of the ozone proposal
would reduce the risk of significant decrease in children’s lung functions by 1.5
million to 2 million incidences per year, reduce the risk of moderate to severe
respiratory symptoms in children by 200,000 to 400,000 incidences per year, and
prevent 1,600 hospital admissions and 5,000 emergency room visits annually. The
standards will have many additional effects, both positive and negative, but under the
Clean Air Act and its interpretation by the courts, EPA is prohibited from considering
effects other than public health in the setting of air quality standards.
Thus, much of the debate has focused on the quality of the scientific data EPA
used to reach its conclusions. Representative Larry Combest, chair of the House
Agriculture Committee’s Subcommittee on Forestry, Resource Conservation, and
Research, which held a hearing on the standards April 23, 1997, reflected the views
of many in Congress and in the agricultural community in stating:
The science employed in developing this rule is not up to par, and I’m concerned
that farmers could bear the brunt of a bad policy based on equally bad science....
According to much of the testimony we heard today, it appears the EPA’s
proposed standards do not reflect the science that is available.8
While witnesses at this hearing (including scientific witnesses) offered
information to support this conclusion, proponents of the standards have disagreed
in other forums. Dr. Morton Lippmann, of New York University’s Nelson Institute
of Environmental Medicine, a member of every scientific panel that has conducted
EPA reviews of the ozone and particulate NAAQS since 1980, concludes that there
has never been a proposed standard better supported by the science. He and others
note that the particulate panel of the Clean Air Scientific Advisory Committee
(CASAC) agreed by a vote of 19-2 that fine particles should be regulated, and that
a separate CASAC panel that reviewed the ozone documents reached consensus that
“although our understanding of the health effects of ozone is far from complete, the
document [EPA’s staff paper outlining potential primary standards] provides an
adequate scientific basis for making regulatory decisions concerning a primary ozone9
There is, however, a consensus among both proponents and opponents that there
is a need for additional research, which might lead EPA to further revision of the
8House Committee on Agriculture News Release, April 23, 1997.
9Closure letter from Dr. George T. Wolff, Chairman, Clean Air Scientific Advisory
Committee, to EPA Administrator Carol Browner, November 30, 1995, p. 1.
standards, especially regarding fine particles. There is virtually no monitoring data
for PM2.5. Little is known about the biological mechanisms that lead from inhalation
of PM2.5 to disease or death. And there is controversy concerning whether PM2.5 (a
broad category that includes many different types of particles) or some specific
particle type within the broad category is the appropriate pollutant to regulate.
Ultimately, the issue of the adequacy of the science base for EPA’s proposed
standards could affect agriculture in two ways. First, there is the question of whether
EPA has the scientific data to assess correctly the effects of the pollutants. If the
standards are too stringent, unnecessary costs of control will be incurred, possibly
affecting agriculture adversely. Conversely, if the standards are insufficiently
stringent, unnecessary harm from air pollution may result, which for ozone could
include adverse effects on agricultural productivity.
Second, there is the question of whether further research would implicate
agriculture as a source of air pollutants subject to regulation — for example, as
discussed below, whether agricultural sources of ammonia contribute to adverse
effects attributed to PM2.5 and might be subject to regulation.
The requirement of the Clean Air Act that EPA regularly review the NAAQS
makes it clear that EPA must make a decision on the science base available. What
is at issue is the level at which the standards should be set given the available
Implementation Issues. A number of issues have been raised concerning the
consistency of the proposed standards with current provisions of the Clean Air Act
and the pace at which air quality improvements would occur under the proposed
The Clean Air Act, as written, specifically references the existing 1-hour, 0.12
ppm ozone standard (Section 181) and the PM10 standard (Section 188) in
categorizing nonattainment areas: areas with ozone readings of 0.121 to 0.138 are
defined as Marginal and given a 3-year deadline to reach attainment; 0.138 to 0.160
as Moderate, with a 6-year deadline; 0.160 to 0.180 as Serious, with a 9-year
deadline; etc. Section 182 spells out requirements for each of the five ozone
noncompliance categories, and Section 185 contains specific enforcement
requirements for the two worst categories (Severe and Extreme) if they fail to attain
the standard within the deadlines. Similarly, Section 189 spells out requirements for
the PM10 noncompliance areas.
When the ozone standard changed from 0.12 ppm to 0.08 ppm, the statutory
definition of the 5 nonattainment categories became an anomaly, requiring measured
progress toward a standard that no longer exists -- even though virtually all parties
concede that the ozone control measures required under the law are the same types
of controls one would use to meet the new standard.
Since EPA is proposing to retain the existing PM10 standard, the question of
references in the CAA specifically to PM10 as the PM standard poses less of a
problem. Nevertheless, the measures outlined in Sections 188-190 do not address
compliance with the PM2.5 standard.
EPA has set forth an implementation plan for dealing with the transition to new
ozone and PM standards, but the implementation plan itself raises questions. The
issue is not whether EPA can implement new ozone and PM standards: the Act
provides EPA general authorities to implement air quality standards. The issue is
whether EPA can disregard specific statutory requirements relating to the existing
standards, as implied by the implementation plan.
A related set of questions concerns what all acknowledge is likely to be a
lengthy process for implementing the new standards. As noted earlier, after
promulgation of the standards, it is 5-8 years before any regulatory decisions
affecting industry or other economic sectors are required to be implemented by the
states based on the revised ozone standard, and 10-12 years before any regulations
are likely to be promulgated implementing the PM2.5 standard. Lawsuits challenging
the standards may cause further delay.
With regard to fine particulates, the lengthy schedule for implementation leads
some to conclude that conducting further research to obtain greater certainty before
regulating would have little impact on public health, particularly as several existing
clean air programs, such as Title IV (concerning acid precipitation), will reduce PM2.5
in the interim. The same set of facts prompts others to suggest that the standard
needed to be promulgated as soon as possible to shorten what is certain to be a
lengthy implementation process. There is general agreement that EPA will still have
time to revisit the PM2.5 standard in 5 years, as required by the Act, before any
measures are taken to control emissions.
Proponents of acting now argue that the standards can be revised based on
additional research, but that without a commitment to move forward with regulations,
there will be little impetus to conduct the additional research. Proponents of delay,
on the other hand, argue that huge expenditures of limited resources will be set in
motion by the setting of a standard, and that there should be greater certainty about
the scientific underpinnings before those resources are committed.10
Regulatory Impacts Specific to Agriculture. Even if there were no
controversies over the science or implementation issues, there would still be
questions about how these proposals would impact the economics of agriculture and
other economic sectors. Farmers are less able than many other businesses to pass
increased costs along to those who purchase their products because prices are set in
commodity markets in which individual producers have negligible influence. That
inability, combined with a concern about the potential consequences of these
changes, has galvanized the farm community. Critics of the proposals raise the
specter of especially severe effects on small farmers with limited incomes. Affected
farmers of any size might have any number of controls placed on their actions,
according to these critics, from mandating no till days to requiring that the ground be
10Bills seeking delay of the standards include H.R. 1984 (Klink) and S. 1084 (Inhofe).
Senator Inhofe's amendment (S.Amdt. 1687), although substantially different from S. 1084,
is considered a substitute for the bill. In discussing the amendment during Senate debate,
March 4, Senator Inhofe announced that if the amendment were enacted, he did not intend
to bring up any other legislation or amendments affecting the NAAQS.
moistened before it is worked. These concerns in some part reflect a situation of
uncertainty, as EPA has not stated what guidance it might develop affecting
agricultural activities for states to meet the new standards.
Most of the concerns about costs expressed by agricultural stakeholders reflect
potential costs, based on assumptions about the implementation of the proposed
standards. The uncertainties in the science underlying the standards, as previously
noted, and the uncertainties about how the standards would be implemented, since
this is a future phase in the process, give considerable range to such assumptions
about potential costs. However, it is possible to identify factors concerning each
proposed standard that place certain boundaries on potential costs and indicate with
some specificity which decisions are key to those costs. These boundaries indicate
that, to the extent that agricultural stakeholders are concerned about the costs of
EPA’s proposals, their focus should be on the PM2.5 standard, but that key decisions
that could affect those costs will not be made for 10 or more years.
Ozone Issues. Ozone received relatively little attention at any of the
Agriculture committee or subcommittee hearings. Agriculture recognizes that it is
adversely affected by ozone. Testimony from the National Audubon Society
estimated that ozone can be responsible for up to a 10% loss in crop production.
Because the proposed standard would lower ozone concentrations in agricultural
areas of the South, Midwest, and Northeast, EPA has estimated a $1 billion annual
savings for agriculture based on increased crop yields from this proposal.
Agricultural interests challenge the magnitude of these projected savings.
Part of this challenge is based on a concern that ozone measurements are
generally taken in urban areas, and agricultural representatives believe that ozone
levels are much lower in rural areas. If they are lower, the crop losses and the crop
benefits are both likely to be less than the estimates above. If ozone is not as
significant a problem in rural areas, these critics argue that agriculture should not be
required to address it, as the health benefits would be limited. Some of the
characteristics of ozone pollution in rural areas were identified in a recent policy
forum.11 The authors concluded that with new regulations in place, large areas of the
eastern United States would be in non-attainment and require regional control
strategies, with potentially significant costs. The role agriculture might play is
Proponents of EPA’s proposal respond in two ways. First, unlike other
pollutants for which there are National Ambient Air Quality Standards, ozone is not
emitted directly into the atmosphere, but forms downwind when sunlight and heat
catalyze a chemical reaction between nitrogen oxides (NOx) and volatile organic
compounds (VOCs). Once formed, ozone can be transported long distances from
urban to rural areas. Thus, rural areas are as likely as urban ones to experience high
ozone levels, provided that they are downwind of the sources of ozone precursors.12
11Chameides, W.L., et. Al., Ozone Pollution in the Rural United States and the New
NAAQS. Science. Vol. 276, May 9, 1997. P. 916.
12Maine is a good example. With very few sources of pollution, five counties in Maine
Second, proponents agree with agricultural interests that farmers do little to
generate the nitrogen oxides and volatile organic compounds that cause ozone to
form in the atmosphere. As a result, they argue, agriculture is unlikely to be a target
of regulation under the ozone proposal. In short, they contend agriculture should
benefit from these changes.
The actual measures to be taken to reach attainment would be determined by
states through what are called State Implementation Plans. All states model air
quality based on current emissions and ambient air quality data, and implement
emission control measures sufficient for the models to demonstrate attainment. As
There are thousands of sources of these gases [ozone precursors]. Some of the
more common sources are gasoline vapors, chemical solvents, combustion
products of various fuels, and consumer products. These products can be
frequently found in large industrial facilities, gas stations, and small businesses13
such as bakeries and auto body repair shops.
By sector, the major sources of NOx and VOCs include transportation, electric
utilities, petroleum refining and marketing, chemical manufacturing, paints, and
architectural coatings. The impacts on agriculture from regulating these sources are
most likely to be indirect, primarily the result of engine modifications that could be
required of the manufacturers of farm equipment or fuel modifications that might
increase the cost of gasoline or diesel fuel.
PM10 Issues. The proposed changes in the particulate standards affect both
PM10 , for which the standards would be less stringent, and PM2.5, for which there
would be separate standards for the first time. The numeric standard for PM10 would
remain the same, but EPA would use a different method of calculating attainment
that allows additional days above the standard. The net effect would be that 31 of the
41 counties currently designated nonattainment (many of them rural) would be
reclassified to attainment.14
Agriculture is a major source of PM10, accounting for about 17% of emissions
nationally, according to EPA.15 The mix of emission sources varies in specific air
(several with as few as 30,000 - 40,000 people) exceeded the ozone standard in 1995,
primarily because of pollutants transported downwind from other states.
13U.S. EPA, Office of Air Quality Planning and Standards, National Air Quality and
Emissions Trends Report, 1995, Report No. EPA 454/R-96-005, Research Triangle Park,
NC, October 1996, p. 21.
14Twenty-six of the 31 counties expected to be redesignated attainment are located west of
the Mississippi River, including 5 in California, 5 in Montana, 3 in Oregon, and 2 in
15U.S. EPA, Office of Air Quality Planning and Standards, Regulatory Impact Analysis for
Proposed Particulate Matter National Ambient Air Quality Standard, Draft Document,
Research Triangle Park, N.C., December 1996, p. 6-13.
quality control regions; agriculture may account for a higher or lower percentage of
emissions in specific regions.
Despite being a major source of PM10, agricultural activities have not generally
been regulated under the current standard. Nevertheless, the weakening of the PM10
standard could lower potential costs and regulatory requirements for agriculture in
cases where it is a major source of emissions in current PM nonattainment areas.
PM2.5 Issues. Data are inconclusive concerning agriculture’s role as a source
of fine particles (PM2.5). In large measure, this is because, in the absence of
regulation, there existed fewer than 50 PM2.5 monitors in the entire country. Thus,
most of EPA’s data on the prevalence and sources of PM2.5 are estimates subject to
potentially large revisions.
In formulating its estimates of areas likely to exceed the proposed PM2.5
standard, EPA relied in part on estimated relationships between PM10 and PM2.5 and
in part on monitoring data from representative sites in different regions of the
country. As noted, agricultural activities are major sources of PM10, which is
essentially dust raised from unpaved roads, construction, and tilling, and particles
generated in other mechanical processes; but PM2.5 is thought to represent a different
class of particles, more the products of evaporation and combustion, for which
agriculture is a less likely source, than the result of mechanical processes, such as
EPA’s Regulatory Impact Analysis for the proposed rule identified five potential
sources of PM2.5: sulfur dioxide (SO2), nitrogen oxides (NOx), ammonia (NH3),
secondary organic aerosols (SOA), and fugitive dust smaller than 2.5 microns. The
sources of these pollutants, as estimated by EPA, are summarized in Table 1.
As shown, emissions of SO2 and NOx are by far the largest: SO2 emissions
totaled 29.1 million tons in 1990, of which coal-fired utilities accounted for more
than half; NOx emissions totaled 25.6 million tons, with fuel combustion and vehicles
accounting for nearly all of the total. Agricultural activities, including farm
machinery operating in connection with producing crops, accounted for less than
agriculture accounted for only 200 tons, less than 0.1% of the total SOA emissions
of 221,000 tons.
Agricultural activities do appear to be major sources of the other two categories.
According to EPA, “Livestock feed lots are the largest source of anthropogenic
ammonia emissions (77 percent), followed by crop production (8 percent).” But the
Agency went on to note that “biogenic emissions of ammonia, decomposition of
plants and animals, forest fires and human breath and perspiration also contribute to
ammonia emissions.” As a result, the Agency concluded, “ammonia emissions are
not considered for control in this analysis given that ammonia sources are not
thoroughly inventoried and ammonia controls are not well developed.”16
16Ibid., p. 6-8.
Table 1. Sources of PM2.5 Emissions, 1990
S ource SO2 NOx S econdary A mmo ni a F ug i t i v e Total
Categ ory Org a ni c Dust
Co al -F i r ed 15,222 6,690 0 0 99 22,011
E l ect ri c
High way 568 7,446 48 198 291 8,551
Industrial 3,1063,224217177 6,526
Off-ro ad 242 2,836 23 3 293 3,397
V eh i cl es
incl. oil and
gas- fi r ed
Ch emi cal s, 879 397 7 225 63 1,571
Metals 910 82 0 6 96 1,094
P r o cessin g
Agricu ltu ral 0 0 0 4,186 192 4,378
Li ve s t o c k
Agricu ltu ral 0 10 0 420 838 1,268
Canada 3,194 2,127 17 233 1,225 6,796
Mexico 3,303 710 7 0 105 4,125
Oth er 449 656 116 147 3,502 4,870
Total 29,102 25,581 221 5,449 6,920 67,273
Source: U.S. EPA, Particulate Matter Regulatory Impact Analysis, Draft, December 1996, p. 6-7.
According to EPA, fugitive dust is PM2.5 emitted directly as particles. SO2, NOx and ammonia are
precursors that transform in the atmosphere to form secondary particulate matter. Secondary organic
aerosols are the particulate transformation products of reactive VOCs and atmospheric oxidants.
The fugitive dust “Other” category includes dust from roads and natural sources, and emissions from
residential wood combustion, wild fires, and prescribed burning. Prescribed burning, which accounts
for 5% of other fugitive dust or 0.5% of the total emissions that become PM2.5, includes agricultural
burning and prescribed burning for forest and range management.
The remaining category, fugitive dust, is also a source of concern to farm
organizations. EPA concludes that agricultural activities account for 837,700 tons
of fugitive dust (12% of total emissions) and that production of livestock accounts
for an additional 3%. Fugitive dust, in total, is a relatively small component of the
PM2.5 problem, and EPA argues that one of the major effects of switching from a
focus on PM10 to PM2.5 is to lessen the need to control dust, which in the Agency’s
view is not as significant a pollutant as emissions from power plants and
transportation sources.17 But agricultural interests have not been completely satisfied
by EPA’s response regarding ammonia or fugitive dust; and both sides note that, in
any event, regulatory decisions will be made by the states, not EPA.
Finally, there are specialized agricultural practices that might be locally
important to PM2.5 attainment. One of these is agricultural burning. EPA identified
agricultural burning as part of a category that also included prescribed burning for
forest and range management. Together, these activities are estimated to generate
379,100 tons of PM2.5 annually, about 5% of the direct PM2.5 emissions, or 0.5% of
emissions including precursors. Prescribed burning is unlike other sources of PM2.5,
because it is not a continuous activity. Rather, it is planned and conducted during
confined periods of time. It is unclear from the data whether prescribed burns are
common in areas that might be designated nonattainment, and the Regulatory Impact
Analysis did not address whether measures controlling agricultural burning might be
necessary. Nevertheless, the planned and limited nature of the activity leave open the
possibility that management strategies may be able to accommodate burning within
the proposed standard, a position the EPA Administrator articulated in a letter to the
Secretary of Agriculture, June 5.18 In addition, as promulgated, the 24-hour PM2.5
standard relaxed the proposed standard from 50 :g/m3 to 65:g/m3. This change is
expected to create additional flexibility for episodic sources of fine particles, such as
prescribed burning of agricultural fields or range land.
Concerns about the quality of the underlying scientific research on particulate
matter are related to the potential agricultural impacts of the standards. As noted
previously, at the core of the science issue is the question of whether more research
would help to better define either the problem or the solution, or conversely, whether
the health threat is such that action is warranted now before better information
becomes available. But many other questions have been raised. Examples of the
many questions that were raised in hearings were the potential errors in calculating
the statistical association between particulate matter and health effects, the inability
17In a June 16 briefing for staff of the House Agriculture Committee, EPA presented data
comparing the composition of PM10 and PM 2.5 for three areas. In Washington, D.C., typical
of an eastern city, soil represents 31% of PM10, but only 5% of PM2.5. In Phoenix, Arizona,
representative of an arid western city surrounded by desert and agriculture, soil represents
66% of PM10, but only 16% of PM2.5. In the San Joaquin Valley of California, a heavily
agricultural area, soil is 53% of PM10, but only 7% of PM2.5. The Agency also identified
sources of soil in the air, concluding that in both Washington and Phoenix, roads and
construction sites were the overwhelming sources, not agriculture. See U.S. EPA, Office of
Air Quality Planning and Standards, Emissions, Monitoring and Analysis Division, “PM-2.5
Composition and Sources,” June 16, 1997.
18Letter from EPA Administrator Carol Browner to Secretary of Agriculture Dan Glickman,
June 5, 1997.
to make precise estimates using the agriculture tillage emissions test, basing
estimates of the amount of particulates put into the atmosphere by tillage on limited
bench research with little or no apparent field testing, and the inability to distinguish
the source of the particulates generated by alternative tillage methods. One witness
pointed to a research conclusion that a large portion of the very fine particulate matter
in the eastern United States originates not in this country, but from North Africa, and
a 1996 paper by air quality scientists at the University of California at Davis
exploring this dimension of the problem was submitted for the record.19
Many of the agricultural changes of the past decade are likely to reduce the
volume of airborne particulate matter. The role of the Conservation Reserve Program
(CRP), enacted in 1985, was cited several times by witnesses representing
agricultural interests. The CRP has retired up to 36.4 million acres (about one tenth
of the nation’s cropland) under 10 year contracts. It was given credit for reducing
particulate matter by planting cover crops, usually perennial grasses, on land that had
been cultivated to produce annual crops (air quality benefits may be cited as part of
the justification for reauthorizing and extending the program before it expires in
2002). But this land is only retired for 10 years, and should the program end or the
land be returned to production, it is likely to become a larger source of PM.
Another basic change in agriculture has been the widespread adoption of
conservation tillage techniques, now practiced on about 100 million acres annually.
These techniques leave plant residue from the preceding year’s crop on the ground
to reduce erosion and retain soil moisture. The soil is disturbed less and the farmer
may pass over it less frequently in farm machinery, thus generating less particulate
There was less talk by witnesses at these hearings about how farming might
change as a result of the requirement to control PM. Examples that were identified,
but not discussed extensively, included sweeping machines for harvesting, spraying
the soil before working it, and using Best Management Practices (erosion control
practices that also provide environmental benefits) for discing.
Aspects of agriculture's concerns will be addressed if an amendment to the
surface transportation bill (S. 1173), adopted in the Senate by voice vote, is enacted.
The amendment (S.Amdt. 1687), sponsored by Senator Inhofe, sets aspects of EPA's
implementation plan in law, providing until December 31, 2005 to designate PM2.5
nonattainment areas, and requiring a report to Congress within 2 years of enactment
regarding the ability of the Agency's sampling and analysis methods to differentiate
types of PM2.5 particles. The latter provision, according to Senator Inhofe, was
added to accommodate the agricultural community. The Administration has agreed
to this amendment. In the immediate aftermath of passage, there has been little
public reaction to the amendment by agricultural groups or in the farm press.
19Article attached to the testimony submitted by Mr. Bob Vice, representing the California
and American Farm Bureau Federation.
Testimony from agricultural interests has focused on questions about data and
analysis, including the assessment and characterization of problems and the impacts
of taking action. Based on these questions, these interests have sought a delay before
EPA acts, so that any action will be based on better information and result in
responses by individual farm operators that more precisely resolve problems
addressed in the regulatory regime. In seeking delay, many comments were offered
about the degree to which current farm practices could be threatened as a result of
these new regulations. The accuracy of these predictions can not be verified for the
most part, but they have generated attention and headlines, especially in the farm
At the heart of this issue are a question and a clash of perspectives. The
question is how much does agriculture contribute to the problems that these
regulations will address (and how much can it contribute to the solutions). This
question has several components, including the diversity of natural conditions and
agricultural practices, the quality and age of the available information, the replication
of actual and current agricultural practices in the data and analysis, and whether all
agriculture should be treated the same in all airsheds. One witness commented that
agriculture is not like the large stationary sources that EPA traditionally regulates,
and the structure of the environmental regulatory regime is far more difficult to apply
to many smaller sources than to few large ones.
The difference of perspectives reflects the different milieus in which the two
agencies operate. Some examples help to characterize this clash. First, EPA science
centers on human health effects, while USDA science centers on effects on
agriculture. At times, scientists with such different foci reportedly encounter
difficulty when trying to communicate with each other. Implementing the
Memorandum of Understanding between the two agencies may help ameliorate these
kinds of problems.
Second, EPA’s statutory mandates are segmented by media. Air quality is
addressed by a separate entity in EPA from water and land issues. In agriculture, the
media are considered together in efforts to help farmers conserve and enhance their
resources. This segmentation has been an effective approach for many problems, but
it may limit both an understanding of the problems agriculture might face and the
range of possible solutions.
Third, the EPA regulatory environment is based on setting national standards
that are applied by state agencies in all airsheds. EPA does not have a program
delivery system at the local level. USDA, by contrast, works almost exclusively at
the local level through direct contact with individual landowners. This approach is
based on voluntary participation, and local flexibility and solutions. One source of
the strenuous objections from agriculture may be a concern over the EPA regulatory
approach as much as the different views on the seriousness of the problem, especially
agriculture’s role. In part, this concern may reflect a misunderstanding of EPA’s
regulatory approach (which does allow states and local air quality control regions
substantial flexibility in designing control strategies) or the time-frame within which
regulations will be implemented, which is likely to be prolonged. Nevertheless, the
different backgrounds or world views that EPA and agriculture bring to the
discussion are a major source of potential misunderstandings.
Fourth, EPA views soil as a potential source of pollutants, and is concerned with
particle sizes and the ways that soil is transported by air in the case of PM.
Agriculture views soil as a basic and valued component for commodity production.
Both EPA and agriculture see major benefits in keeping soil in place on the farm.
Agriculture measures erosion using a tolerance rate that is based on the gross volume
of soil that can be lost while maintaining the long-term production capability. EPA
is concerned with particle size that is transported by the processes of erosion.
Agriculture believes that appropriate soil conservation measures, properly designed
and implemented, should go a long way to solving its definition of the problem, that
is, loss of an asset, while the EPA is basically concerned with solving the particulate
matter problem. While both strive to keep as much soil in place as possible, the
different objectives and possible solutions make common ground on the most
appropriate erosion control measures more difficult to find.
A June 5, 1997 letter from Carol Browner to Dan Glickman stated that EPA did
not plan to focus on agricultural sources as it implemented the proposed standards.
The letter states that agriculture would benefit from the change in the ozone standard,
by reducing crop damage. Regarding the PM proposal, EPA states that it plans to
issue guidance to states that would direct their control strategies away from farming
and tilling activities. The letter also states that burning is a recognized agricultural
practice, and that strategies that can accommodate burning will be sought.
The hearings before congressional committees reflect a call to Congress by
agricultural interests (and others who might be adversely affected) to hear their
concerns and explore these issues, and to consider acting on their behalf. They also
represented an attempt to influence EPA’s decision-making process.
Continued congressional oversight of these issues is certain. EPA will need a
continuing flow of resources to review monitoring data submitted by the states,
categorize areas as nonattainment, review new State Implementation Plans, and
promulgate regulations affecting specific sources of pollution. The conferees on
EPA’s FY 1997 appropriation expressed their concerns about the new PM standard
even before its proposal. The appropriations committees will continue to monitor
these regulations. More broadly, some have suggested free-standing legislation (such
as H.R. 1984 / S. 1084) to impose a moratorium on implementation of the new
standards. While enactment of such legislation appears less likely as time goes on,
the Senate's adoption of S.Amdt. 1687 to the surface transportation bill in early
March indicates a continued search for legislative language that can reassure affected
interests and narrow Agency discretion in implementing the new standards. (For a
discussion of recent congressional actions on clean air issues, see CRS Issue Brief