By Saqib Mukhtar and Brent W. Auvermann
Professors and AgriLife Extension Agricultural Engineering Specialists, The Texas A&M System
The concentration of large numbers of livestock and poultry confinement facilities, which began several decades ago, has become common practice in the animal industry. Until recently, the operators of animal feeding operations, or AFOs, did not have much knowledge about the Clean Air Act (CAA) and its implications for animal agriculture. Now, however, air quality standards are being strictly enforced.
Figure 1:Chicago in the summer 2000:and a poor visibility day (right) with PM2.5~35µg/m3. (Source: USEPA http://www. epa. gov/airnow/2003conference/presentations2003/Paisie.pdf, accessed February 21, 2006)
Figure 1: Chicago in the summer of 2000: a clear day with PM2.5<5µg/m3;(Source: USEPA http://www. epa. gov/airnow/2003conference/presentations2003/Paisie.pdf, accessed February 21, 2006)
National Ambient Air Quality Standards
Air pollution is categorized as a health concern for humans, animals or plants when, for example, an amount of pollutants in the air is considered to be harmful. It can also be a nuisance because of odors interfering with the enjoyment of life or normal use of property.
The first national legislation to deal with air pollution was the Air Pollution Control Act of 1955, which was followed by the Air Quality Act of 1967. Three years later came the CAA Amendment, an important piece of environmental legislation intended to curb air pollution—particularly smoke and smog—from large,industrial cities. This legislation required the U.S. Environmental Protection Agency (EPA) to establish National Ambient Air Quality Standards (NAAQS).
The NAAQS were developed for six “criteria pollutants” that the EPA considered to be common throughout the United States:
- Carbon monoxide (CO),
- Lead (Pb),
- Nitrogen dioxide (NO2),
- Ozone (O3),
- Particulate matter (PM) and
- Sulfur dioxide (SO2).
These pollutants were called criteria pollutants because they were based on two criteria: primary standards to protect public health; and secondary standards to protect public welfare, such as decreased visibility (Figs. 1 and 2) and damage to animals, crops, vegetation and buildings. Table 1 lists the primary and secondary standards for these criteria pollutants.
Because different pollutants have different effects on public health and welfare, the NAAQS for these criteria pollutants are also different. Some pollutants have standards for long-term and short- term averaging times. The short- term standards protect against acute or short-term health effects, while the long- term standards guard against chronic health effects. The amounts of these pollutants are reported as concentration in parts per million (ppm) by volume, or as mass concentration in milligrams per cubic meter (mg/m3) and micrograms per cubic meter (µg/m3) of air.
Fig2: Reduced visibility because of PM emission from animal feeding operations
Table 1 shows that all criteria pollutants except carbon monoxide have primary and secondary standards. In 1997, the EPA divided particulate matter into two categories (PM10 and PM2.5) to designate different size particles. PM2.5 is also known as PM fine (Table 1).
Throughout the United States, a network of approximately 4,000 State and Local Air Monitoring Stations (SLAMS) provide air quality data to determine if regions are meeting or exceeding the NAAQS.A geographic area is deemed a “non-attainment area” if the NAAQS for a certain criteria pollutant is exceeded. Regions staying at or below the NAAQS are known as “attainment areas.”
Figures 3 and 4 illustrate both categories for two criteria pollutants: PM10 and ozone. Western states, especially California and Arizona, are classified mostly as serious nonattainment states for PM10 (Fig. 3). Large urban areas in several states, including Houston, Los Angeles, and Dallas, are considered non-attainment areas (Fig. 4) for the 8-hour ozone standard.
Figure 3: PM non-attainment area map. (Source: USEPA, http://www.epa.gov/air/oaqps/greenbk
/mappm10.html, accessed February 2, 2011)
The EPA, state and regional pollution control agencies have been monitoring air quality and reporting emissions for criteria pollutants since the 1970s. Data in Table 2 indicate that the emissions of individual pollutants have decreased steadily over time and that the total emissions of these pollutants in 2009 were less than half of what they were in 1980.
In 1990 the CAA was amended, authorizing the EPA to fine violators. The act contains eleven separate titles for addressing air quality issues. One of them is Title V.
EPA and state air pollution regulatory agencies (SAPRA) grant Title V permits to operate major, stationary sources of pollution. An AFO, or any other operation, is considered a major, stationary source of emission if it has the potential to emit more than the annual emission threshold for a criteria pollutant. Major sources must pay an annual fee on every ton of regulated pollutant emitted, including fugitive emissions.
Fugitive emissions are to air what non-point source emissions are to water and cannot be measured at the end of a pipe or orifice. For example, if a source is subject to Title V permitting because of its PM10 emissions, then it must pay annual fees on all other criteria pollutants (e.g., Sox, NOx and O3) that it may emit.
Figure 4:Ozone non-attainment area map.
Hazardous Air Pollutants (HAPs)
The EPA also considers substances such as volatile organic compounds (VOCs), pesticides and herbicides as toxic air pollutants. It maintains a list of these substances on its web site (http://www.epa.gov/air/toxicair/newtoxics.html, accessed Feb. 8, 2006). Toxic air pollutants, also known as hazardous air pollutants (HAPs), cause— or are suspected to cause—serious health effects (e.g., cancer and birth defects) or adverse environmental effects.
Two particular gases, ammonia (NH3 ) and hydrogen sulfide (H2 S), are not listed as HAPs. However, H2 S is included in the CAA [section 1 2- 9(r)] and is subject to accidental release provisions. Higher emissions of NH3 may cause the formation of ammonium aerosol, which reacts with acids (e.g., nitric or sulfuric acid) in the atmosphere and contributes to the formation of PM2.5 or soil and water acidification.
Ammonia and Hydrogen Sulfide Reporting Requirements
Since January 2009, one federal rule has required reporting NH3 and H2 S emitted from point sources at large AFOs. Examples are exhaust from confinement structures, such as a mechanically ventilated barn, and manure storage/treatment structures, such as lagoons. This reporting requirement falls under the Emergency Planning and Community Right-To-Know Act (EPCRA).
This legislation is not part of the CAA, but the rule requires that releasing these two contaminants above a “reportable quantity” be reported. The reportable quantity for NH3 and H2 S is 100 pounds within any 24-hour period. EPCRA fines violators $27,000 and $10,000 per violation, respectively. A description of EPCRA rule and what size AFOs may be exempt from reporting requirement is provided by the EPA EPCRA CAFO Reporting fact sheet at http://www.epa.gov/osweroe1/docs/chem/CAFO_rule_fact_sheet.pdf (accessed February 2, 201 ).
Unlike criteria pollutants, HAPs and other toxic air contaminants, odors are not federally regulated under the CAA. Generally, SAPRAs and/or local, regional or municipal authorities regulate odors under the nuisance standard.
Texas and most other states indirectly regulate odors through setbacks, permitting, operator training and land-application restrictions. A few states require direct methods, using rules and standards that prohibit the release of odors above odor detection thresholds which are measured at the AFO or which are determined in the laboratory from odorous air samples.
Operators of concentrated animal feeding operations face increased scrutiny and accountability for the extent to which their facilities may impair air quality for their neighbors and communities. That accountability can involve nuisance complaints, lawsuits, increased permitting burdens, novel or stricter applications of existing law, new municipal ordinances, or state and federal regulations. It is a complicated, multi-faceted challenge that will require AFO operators to stay abreast of developments and new precedents on all of those fronts.
In the meantime, operators should become familiar with fundamental air quality principles,which will help them devise innovative strategies or adapt existing techniques to reduce the air quality impact of their facilities. This will also enable them to anticipate how management techniques to reduce one air pollutant might create or intensify problems with another air pollutant. Producers should educate their neighbors and communities about these issues where possible so that they can reduce the likelihood of destructive, expensive confrontations over nuisances or regulatory violations.
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