Agriculture and EPA's New Air Quality Standards
for Ozone and Particulates

Concluding Observations

List of Tables

Table 1. Sources of PM2.5 Emissions, 1990

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 firsi 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 EPA15 The mix of emission sources varies in specific air 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 Irart 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 tilling.

EPA's Regulatory Impact Analysis for the proposed rule identified five potential sources of PM2.5: sultur dioxide (S02), nitrogen oxides (N0x), ammonia (NH3), secondary organic aerosols (SOA), and ftigitive 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 0.1% of each of these pollutants, according to EPA's estimates. Similarly, 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 rmjor sources of the other two categones. 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

Table 1. Sources of PM2.5 Emissions, 1990
(thousand tons)

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 precribed burning. Prescribed burning, which accounts for 5% of other fugitive dust of 0.5% of the total emissions the 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 fligitive 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 PM15 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 fligitive 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 PM25 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 PM25 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 nonattalnment, 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 518 In addition, as promulgated, the 24-hour PM25 standard relaxed the proposed standard from 50 ug/m3 to 65ug/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 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 Mrica, 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 matter.

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 nonattnment 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.

Concluding Observations

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 press.

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 97007, Clean Air Act Issue.)

EndNotes

14 Twenty-six of the 31 counties expetedto be redesignated attainment are located west of the Mississippi River, mcludmg S in California, 5 in Montana, 3 in Oregon, and 2 in Washington..

15 U.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.

16 Ibid., p. 6-8

171n a June 16 briefing for staff of the House Agriculture Committee, EPA presented data corriparing the composition of PM10 and PM 2.5 for three areas. In Washington, D.C., typical of an eastern city, soil represents 31% of P10 but only 5% of PM2.5. In Phoenix, Arizona, representative of an arid western city surrounded by desert and agriculture, soil represents 66% of PM 10' but only 16% of PM25. 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 Ouality Planni~ and Standards, Emissions, Monitoring and Analysis Division, "PM2.5 Composition and Sources," June 16, 1997.

18Letter from EPA Administrator Carol Browner to Secretary of Agriculture Dan Glickman, June 5, 1997.

19Article attached to the testimony submitted by Mr. Bob Vice, representing the California and American Farm Bureau Federation.