OCAMM Seminar Series
Air Quality


Click on title to view presentation.  Presentation date in parenthesis.

Odor and dust control for animal facilities
Dr. Yuanhui Zhang, University of Illinois (2000)
Potential impact of air quality standards on livestock and poultry production systems
Dr. Heny Tyrell, USDA-CSREES (2002)
ISU's odor reduction issues: Current and past programs
Dr. Jeffrey Lorimor, Iowa State University (2003)
Air quality in Ohio livestock farms
Dr. Lingying Zhao, Ohio State University (2003)
Formation and disappearance of select odor components of manures as influenced by management
Dr. Lynn Willett, Ohio State University (2003)
Monitoring and control of ammonia and particulate emissions from Ohio poultry facilities
Dr. Lingying Zhao, Ohio State University (2005)
Issues for regulating air quality on livestock operations
Dr. Calvin Parnell, Texas A&M University (2005)
The AFO Air Quality Agreement: Background, implementation and impacts
Sharon Nizich, U.S. Environmental Protection Agency (2005)
Wet scrubbers to control ammonia emissions from animal buildings
Roderick Manuzon, Ohio State University (2005)



Odor and dust control for animal facilities
Dr. Yuanhui Zhang, University of Illinois

Air quality is diminished by dust, a health hazard, and odor, a public nuisance.  Studies indicate that increased levels of dust inside animal facilities can  impact human’s physiological processes.  Compared to field dust, dust from livestock facilities is biologically active, produced in higher concentrations and provides a vehicle for transporting volatile compounds and odor molecules.  While dust can be measured, odors present a greater challenge.  What humans detect as an odor is a complex interaction of 100’s of different molecules.  Additional work is needed to establish the relationship between sensory and analytical measurements.  Strategies to improve air quality include controlling the source of dust and odors by methods such as sprinkling oil, varying feed rations and managing manure effectively.  Mechanical, electrical, biological or chemical air cleaning as well as improving ventilation effectiveness can also enhance indoor air quality.  Technologies such as using thermal chemical processes to convert swine manure to oil and separating dust and odor by centrifugal force without filtration show promise for improving air quality.  The challenge is developing cost effective technologies.

Rick Stowell (OSU) referred to the separator designed by Zhang that uses centrifugal force filtration to  decrease dust and gaseous emission in a livestock facility.  Stowell questioned how ammonia is separated.  Zhang responded that the second-generation prototype uses diffusion coagulation separation.  The diffused ammonia will attach to larger particles and to water, allowing separation.

Stowell questioned the effectiveness of the separator in removing hydrogen sulfide and other odors.  Zhang replied that other gases have not been measured.  The goal has been to understand the effectiveness on reducing dust and ammonia.  He expects to collect samples of other odors this spring.

Mike Lilburn (OSU) commented that from a poultry perspective, the challenge is maintaining a moisture level that minimizes dust but does not increase odors.  He noted the need for a 2-phase model that controls moisture and ammonia at the same time.  Zhang noted that ventilation effectiveness can reduce both dust and odors.  However, the effect on odors is not as significant as they are more diffuse.

Lilburn noted that the in poultry houses, the stratification of dust and ammonia may have different impacts on humans compared to chickens.  Should human or avian response be used in determining air quality?  Zhang commented that air quality standards may be based on human health, animal performance or both.  It is possible to have zoning within a given area.

Ted Short (OSU) asked if Zhang had ever worked with biofilters and, if so, for what particle sizes are they effective.  Zhang replied that while biofilters have been shown to be effective in reducing odors, very little fundamental research has been done.  There is little understanding of the organisms within a biofilter, their effect on odors and the reaction time required.  Zhang also noted that biofilters are often regularly sprayed with water which may act as a scrubber for ammonia and other water soluble odors.

Dave Elwell (OSU) observed that while Zhang has not concentrated on odor reduction measurement, he seems to be moving in that direction.  How important are fatty acids in measuring odors?  Zhang noted that a linear relationship exists between volatile compounds with the intensity of sensory measurements.  While such a relationship may not exist between odor and fatty acids, Zhang hopes to establish some sort of relationship between the two.

Elwell asked if compounds other than fatty acids would be excluded from measurements or whether fatty acids can serve as a marker to indicate the response of other odor compounds.  Zhang noted that other molecules do contribute to odors and that volatile compounds probably have the greatest impact.

Fred Michel (OSU) asked whether Zhang’s model depicting the spatial distribution of dust in a simulated house was based on fluid dynamics.  Zhang responded that the flow patterns were actual measurements made using a multi-point sensor. 

Michel questioned how the ventilation effectiveness of a 12 by 18 foot room is measured.  Zhang illustrated the glass walls of the room.  Photographs of the circulation are taken of 1-millimeter helium bubbles.  The bubble “paths” indicate the air velocity.  Helium is used as it has the same density as air, resulting in neutral thermal buoyancy.

Potential impact of air quality standards on livestock and poultry production systems
Henry F. Tyrrell, USDA-CSREES

Although ammonia is not identified as a pollutant under the EPA’s Clean Air Act, it reacts with sulfur dioxide and nitrous oxides in the atmosphere to form particulate matter with a mass median diameter of 2.5 microns (PM-2.5).  In 1997, the EPA implemented new standards restricting the atmospheric concentration of PM-2.5.  Based on current monitoring of PM-2.5, the EPA is expected to designate areas of non-attainment by 2005 after which regulations will be implemented requiring states to set mandates for compliance.  The states will have until 2017 to meet the PM-2.5 standards, although two one-year extensions are possible.

Ninety percent of ammonia emissions to the atmosphere are associated with agriculture. Based on the EPA’s inventory of ammonia emission factors, cattle produce the highest amount followed by poultry, hogs then inorganic fertilizers.  Calculations by animal scientists indicate that the EPA’s factors may be up to 40% too low.  Although manure management has focused on the release of nitrogen and phosphorus to water resources, it is clear that ammonia releases to the atmosphere will also have to be managed.  At this time, there is no technology that that can eliminate ammonia and more research is needed to reduce emissions, better understand the flow of nutrients in a system and identify tradeoffs of alternative systems.

Harold Keener (OSU) questioned the realistic objective for ammonia reduction.  Tyrrell responded that the EPA will determine the reduction based on the significance of the contribution to air degradation relative to other sources.

Steve Loerch (OSU) asked if CAFOs would be targeted in areas that do not attained PM-2.5 levels.  Tyrrell noted that the EPA will first identify the concentration of PM-2.5 that clearly demonstrates human health impairment.  Based on this concentration, non-attainment areas will be designated and then all sources contributing to PM-2.5, including ammonia emissions, will be identified.

Ted Short (OSU) asked whether other animals and microbes have been analyzed for their contribution to ammonia in the atmosphere.  Tyrrell replied that he had not received an answer from wastewater treatment industry as to microbe output and the EPA’s inventory does not include them.  Keener noted that wastewater treatment plants transfer nitrogen to a form that is eventually released as nitrogen gas, assuming the plant is well managed.

H.R. Conrad (OSU) suggested that most nitrogen on farms is not from cattle but vegetation.  Tyrrell responded that as vegetation decomposes, it is usually an aerobic process.  As a result, nitrogen is converted to ammonium, nitrate or nitrous oxide rather than ammonia.

Fred Michel (OSU) asked if the USDA is funding research to identify methods of reducing ammonia emissions.  Tyrrell noted that support is growing.  Funds previously designated for the IFAFS program are expected to be appropriated under the USDA/SCREES Competitive Grant Program, assuming Congress passes the appropriations bill.

Chris Reynolds (OSU) asked what technologies can be used to decrease ammonia emissions.  Tyrrell replied that it will take a systems approach, using a combination of techniques that will vary with species.  One technique is to fine-tune feed to meet amino acid requirements, reducing excess nitrogen.  A Dutch farm has demonstrated that the separation of urine and feces* can help reduce the volatilization of nitrogen to ammonia.  The smooth floor is channeled to allow urine to be collected and stored in a separate pit while the manure is scraped continuously.  This dairy uses other techniques in its systems approach and has reduced ammonia emissions by 60%.  (may not be economic in the US).  For confined production, the ammonia can be captured via filters or traps.

*Note:  Urease, found in livestock feces, catalyzes the hydrolysis of urea to ammonia.  Thus, efficient separation of feces and urine can slow down the reaction.

Don Palmquist (OSU) requested comments on composting and ammonia emissions.  Tyrrell responded that composting aerates the manure, releasing ammonia that should be trapped or filtered.  Some research on changing feed to reduce urine pH to less than 6 indicates a significant reduction in the volatility of ammonia.

Andy Rogowski (ODA) described a belt system for transporting chicken manure to an enclosed composting site that reduces ammonia formation by 50%.

Loerch asked how soil ureases act on urine to release ammonia.  Tyrrell explained that is an efficient enzyme that is endemic in soil and, if it is in contact with nitrates on the soil surface, ammonia is released.  If urine is incorporated into the soil, nitrification should occur instead.  This is what is thought to happen in a grazing situation; however, additional research is needed.

Michel asked whether reduction of sulfur dioxide and nitrous oxides in the atmosphere as required under the Clean Air Act have reduced the problem with ammonia.  Tyrrell agreed that it has reduced the problem to some extent, but it still exists.  Also, free ammonia causes other chemical problems with different impacts.

Floyd Schanbacher (OSU) asked at what rate urine is converted to ammonia and whether separation of manure and ammonia changes that rate.  Tyrrell noted that the Dutch dairy mentioned previously was able to reduce the conversion by two-thirds although the storage of urine in a closed contained contributed to the reduction.

Schanbacher asked if urease inhibitors are effective.  Tyrrell responded that they are effective but are expensive and require high concentrations.  Also, their effectiveness is reduced with wet conditions.

Reynolds suggested that national regulations for ammonia emissions are needed because variations in state regulations may result in the migration of livestock production to states with the most lax regulations.  Tyrrell noted that such movement has already occurred with California dairies leaving the state which is expected to impose ammonia standards soon.  The Chino Valley in California has the highest concentration of atmospheric ammonia ever measured.  The valley has approximately a half million cows in 10 square miles on open lots.

ISU’s odor reduction issues:  Current and past programs
Dr. Jeffery Lorimor, Iowa State University

Public concerns regarding livestock production in Iowa have influenced research and legislation.  In 1996-97, Iowa State University (ISU) evaluated the effectiveness of odor control technologies on eighty livestock farms of varying size and producing primarily swine.  The technologies evaluated were synthetic covers, aeration, biocovers, pit additives, soil injection, anaerobic digestion, composting and landscaping.  Odors were evaluated by field staff using scentometers and by field day participant’s reports during activities, especially land application.  In 2002, ISU received 562 responses to a swine survey to assess odor complaints and technologies used on swine production facilities throughout the state.  Results from the demonstration project and surveys indicated a wide range of costs and effectiveness of different technologies and concluded that there is no one best solution for odor reduction.

Although the state, in an effort to maintain consistency, regulates Iowa’s livestock facilities, citizen action groups have advocated for greater control at the county level.  Current state regulations are designed to protect water quality and stipulate separation distances depending on the designated area, the number of animal units (AU) and application type and rate.  New air quality rules, based on human health impacts, will limit hydrogen sulfide and ammonia concentrations.  To allow some local control, the state is working to implement a master matrix to approve new farms larger than 1,000 AU and expansion farms larger than 1,666 AU.  Each facility will be scored based on a number of parameters that affect water and air quality and the total score will determine approval.  Both the state and county will have the right to appeal.

For more information about the odor demonstration project results, click here.

Lingying Zhao (OSU) asked the optimum size for using a biocover to reduce odor emissions and the thickness of straw needed.  Lorimor noted that the biocover is effective only for earthen or concrete liquid slurry storage as a lagoon has too large a surface area.  The maximum size is 120 feet, although it may be possible to increase that somewhat if windbreaks or twine or other restraint is used across the top of the straw to hold it in place.  A layer of 8 –12 inches of straw is needed.

Harold Keener (OSU) asked if there are recommendations for specific species such as a two-stage dairy lagoon.  Lorimor replied that controlling water in a dairy operation is effective and aeration can significantly improve odor control in a lagoon but it is expensive.  For deep pit swine manure storage, there are not many choices.  The floor may be sprinkled with oil to reduce the dust which is associated with approximately 50% of the odor; however, it is not often used as it makes the floor slippery.  For solid manure systems, frequent cleaning and composting are effective.

Lorimor suggested that most odor complaints occur during land application.  The use of injection equipment to incorporate liquid manure can reduce odors at that time.

Fred Michel (OSU) asked if treating the exhaust air from a deep pit storage is effective.  Lorimor responded that biofilters can reduce odors but require that the building be mechanically ventilated. 

Keener asked about the relationship between the state and federal EPA in regulating emissions.  Lorimor noted that at the federal level, the EPA is concerned with identifying emission factors for specific species.  The state is more concerned with the concentration of emissions and the potential health effect on the nearest downstream entity.

Keener cited a Minnesota study of livestock facilities which indicated a high variance in emissions and asked how such differences can be reconciled.  Lorimor suggested that the EPA will eventually set a limit in terms allowable emissions per day and that the state will be responsible for enforcement.  At this time, the Iowa Department of Natural Resources has concerns about the accuracy and quality control for measuring emissions.

Lynn Willett (OSU) asked about the scentometers used during the odor demonstration project.  What is measured?  What is the sensitivity?  Lorimor noted that there is little correlation between ammonia or sulfur dioxide and odor.  The scentometer is used in as attempt to measure actual odor.  An adjustable carbon filter is used to control the detection threshold.  However, the instrument is not very accurate because the user has already been exposed to the odor and is affected by visual cues.  An olfactometer, which uses bagged air that is mixed then assessed by an odor panel in a sterile room, is more effective because there are fewer variables.

Michel asked if the setback distances make it difficult to achieve the concentrations for hydrogen sulfide and ammonia as required by regulations.  Lorimor noted that the levels are low enough that there should be no problem if setbacks are maintained.  However, there is a potential for exceeding the concentrations during application, especially if a broadcast spreader is used.  Also, layer facilities may have more difficulty than swine facilities.

Air Quality in Ohio Livestock Farms
Dr. Lingying Zhao, Ohio State University

Concerns regarding airborne emissions from Ohio livestock facilities are being addressed by ongoing research to assess farm air quality and farm worker exposure as well to provide preliminary data for government agencies, producers and researchers. Considering the fact that the air emission data is not easily transferable from other states or country due to variations in geographical regions, climate conditions, management practices, animal growth cycle, building types and ventilation systems, it is very meaningful to have air emission data collected from Ohio farms.  The study uses a variety of instruments to measure weather conditions, indoor environment (air velocity, temperature, humidity, static pressure), gasses (ammonia, hydrogen sulfide, carbon dioxide), dust (concentration, size distribution, toxicity), and odor in typical Ohio farms in three seasons.  In March 2003, measurements were made at three sites:  1) high-rise chicken layer farm; 2) swine finishing farm with deep pit; and 3) free-stall dairy farm with natural ventilation.  Although more data are needed and continuous measurement is ideal, preliminary measurements indicate that, gas, dust and odor levels are very low in farms in early Spring.  However, dust in the poultry house and odors in the swine barn are relatively higher than that in the other facilities.  In 2004, three different animal facilities will be added to the study.

Harold Keener (OSU) asked if the data presented was based on single measurements or replications.  Zhao responded that they were one time measurement taken in March 2003.  For each facility, measurements were made at fourteen different locations both inside and outside the building.  She plans to take measurements at each facility during each season to identify seasonal variations.

Keener asked if dust measurements outside the poultry facility were made before or after those inside (Note: Zhao had reported that entering the building caused high activity, increasing dust levels).   Zhao replied that in all cases, the first measurements made were where the lowest results were expected so as not to affect the equipment.

Jon Rausch (OSU) asked whether the particle size of the dust had been measured.  Zhao noted that the data were collected but need to be summarized.  The measurements are being made to reflect human breathing.

Rausch questioned whether bacteria associated with the dust are being cultured to determine what species are present.  Zhao responded that it is work that is just beginning.

Rausch asked if there are other studies available across the country that would provide a benchmark.  Lingying confirmed that Purdue, Illinois and Minnesota had conducted some farm studies; however, data can vary significantly in different locations.  Therefore, findings in other states are often not applicable in Ohio.

Rausch asked if the differences are due to different feeding practices.  Zhao agreed that feeding is one parameter that may have an impact and indicated that the difference is true for gases and odors as well as dust.  There are many European studies but the findings are not transferable to the U.S.

Keener questioned which facilities could pose the greatest risk from a health standpoint.  Zhao noted that, of the gases measured, carbon dioxide is generally not a health risk but is an indicator of freshness of air and effectiveness of the ventilation system.  The health risks from dust is that it can carry pathogens and odors, which may be an irritant or cause psychological impairment, and the size of the particulate matter may cause or exacerbate respiratory illnesses.  For hydrogen sulfide, OSHA standards are 10 ppm for 10 minutes but more clarification on long term exposure at lower levels is needed.   Zhao stressed that the risks vary with both concentration levels and length of exposure and that additional studies are needed before setting standards.

Formation and Disappearance of Selected Odor Components of Manures as Influenced by Management
Dr. Lynn Willett,  Ohio State University

Many studies have been conducted to determine malodors from manures and composts.  The majority of these have been based on subjective measurement of perceived odors or have been measured in association with non-quantifiable matrices such as open streams of air.  A major limitation of such studies is that it is very difficult to correlate concentrations of specific malodorous compounds with bioprocesses that form or destroy the offensive chemicals.  The studies reported in this seminar were designed to monitor and quantify a select group of known malodorous chemicals in dairy manures and during composting.

To analyze odor components, fresh, aged and composted dairy manures were placed in closed vessels that permitted accurate monitoring of influents, effluents, and temperature. The compounds quantified, volatile fatty acids (6), phenolics (2), indolics (2) and ammonia, were measured over sixteen days.  The experimental variables for these studies were: fresh vs 12-day aged manure; days of composting; freestall barn of manure origin (lactating cows vs growing heifers); and intermittent vs continuous aeration.  Aging of all manures greatly increased the concentrations of all the chemicals studied, however, increases in the various compounds were not proportional.  Formation of the chemicals was very rapid and appeared to reach steady state by 6 to 8 days.  Aerobic composting rapidly destroyed the odorous chemicals with the onset of composting.  Most of these chemicals were absent from the composting mass by 7 days and only traces of acetate and iso-butyrate were present by day 16.  Analysis of the exhaust stream revealed that only small quantities (<0.25%) of the chemicals were released to the atmosphere and those only occurred with excessive (continuous) aeration.

Emissions of ammonia were not influenced by aging of the manures.  However, the source of manure and extent of compost aeration had significant effects.  Manures from the lactating cows that were fed rations containing 18.7% protein emitted significantly more ammonia than from growing heifers that were fed 13% protein rations.  Similarly, the continuous aeration (29 kg/day) emitted twice as much ammonia as the intermittent aeration (6 kg/day).

These studies demonstrated that preventing anaerobic storage of manures, even for short intervals, is important in any odor control strategy.  Composting can quickly utilize odor causing chemicals, however, it is desirable to strive for minimal aeration.  Excessive aeration drives malodors and ammonia to the atmosphere.  These studies provided additional quantitative evidence that feeding excessive quantities of nitrogen (protein) will result in increased ammonia emissions to the atmosphere.  Considering that livestock production is responsible for up to 75% of the atmospheric ammonia, animal husbandry and manure management practices that reduce these emissions are prudent.

Maria Sol Morales (OSU) asked about the consistency of dry matter concentration.  Willett responded that variations reflect differences in seasonal temperature and precipitation.  Also, because urine is present in the manure, as pH increases during composting, the formation of ammonia increases.

Harold Keener (OSU) questioned the impact on the environment if no ammonia were emitted to the atmosphere.  Would it affect the sustainability of the plant ecosystem?  Willett noted that based on EPA data concerning amounts emitted, it should not be a problem.

Maurice Watson noted that there is some evidence that too little contact with animals has increased the incidence of asthma in the U.S.  Willett cited a University of Pittsburgh report that suggests that decreases in sulfur emissions by power plants has resulted in an increased concentration of nitrates in the atmosphere and that nitrates are more irritating to lung tissue than sulfates.

David Munn (ATI) asked if any data are available documenting the potential impacts of CAFOs (confined animal feeding operations) on health.  Willett noted that the data on chronic exposure (long term, low concentration) are poor as there have been no controlled studies.  However, acute exposures (short term, high concentration) are documented and can be very serious.

Keener suggested that during the summer when ventilation rates for livestock building are high, ammonia concentrations in the building are low.  In general 10 ppm is the level which begins to affect animals and it may get to as high as 20 ppm during winter months.

Floyd Schanbacher (OSU) asked for clarification of differences in ammonia levels in manure from lactating cows as compared to heifers. Also, what has the greatest impact on ammonia production - protein, urine or amino acids?   Willett confirmed that emissions vary during composting for different manures and that urine has the greatest effect.  Schanbacher noted that urease activity (catalyst for ammonia production) is increased when feces are in contact with urine.

John Lengacher (ATI) asked how the loss of ammonia affects the use of manure as a fertilizer.  Willett replied that any loss of nitrogen in the form of ammonia, decreases the nitrogen in the manure.  There are three ways to minimize ammonia formation:  1) separation of urine and feces; 2) management of nutrition and manure storage and handling; and 3) treatment.

Schanbacher asked if pH levels as high as 9 reflect the release of urea to free ammonia.  Watson asked if acid had been added to decrease pH.  Willett responded that no acid had been added because data on and understanding of the basic behavior between different inputs was needed first.  The ammonia emissions correlate with other studies that use olfactometry measurements.

Paul Dillon (ATI) asked how compost applied to land can affect different soils as well as reclaimed land from mining.  It was noted that Northern Ohio soils tend to be fertile and sandy whereas Southern Ohio soils are rocky and used more for grazing.  Watson commented that the nutrient content and pH of the final product is important and that compost typically has a pH of 8-8.5  Southeastern Ohio soils tend to be acidic so compost could improve the soil, but in the west it could increase pH too much.  Nitrogen and phosphorus content of the compost should also be considered.

Monitoring and Control of Ammonia and Particulate Emissions from Ohio Poultry Farms
Lingying Zhao, Ohio State University

Recent research at Ohio poultry facilities has assessed indoor environmental and air quality, quantified particulate matter (PM) and ammonia emissions, and evaluated technologies for reducing ammonia and PM emissions.  Two different types of layer facilities were evaluated: 1) high-rise with manure storage below poultry and 2) belt-battery with removal of manure via belts.  Results of the study indicated increased ammonia concentration within the facilities as ventilation rates reduced due to decreased outdoor temperatures; however, emissions from the buildings, while highly variable, overall increased during the summer months.  Although PM10 emissions increased significantly when the birds were disturbed, overall concentrations inside increased and emissions decreased as ventilation rate decreased due to decreased outdoor temperature.  For both ammonia concentrations and emissions were significantly higher in the high rise facility compared to the belt battery which was attributed to the manure being removed from the belt battery facility.  Ammonia emission from manure removed from the belt battery building was not evaluated.
In summary, the annual average ammonia emission from the BB barn 0.29 g/day-hen, which is significantly less than 1.03 g/day-hen of the conventional HR layer barns.  According to the emission rates, 44,400 hens from the HR barn or 158,000 hens from the BB barn would emit 100 lb NH3/day. The mean total suspended particles (TSP) emission rates were 168 and 146 mg/day-hen from the BB and HR barns, respectively.  TSP emissions from the two barns were not statistically different.  The belt battery layer barn has a lower PM10 emission rate of 20 mg/day-bird in comparison with 32.5 mg/day-bird of the high-rise layer barns. According to the emission rates, it would take about 4.1 million hens in the BB barn or 4.7 million hens in the HR barn to emit 250 tons of TSP per year.  It would take about 13.7 million hens in the BB barn or 8.5 million hens in the HR barns to emit 100 tons of PM10 per year.
Evaluation of a particulate impaction curtain indicated a significant decrease in PM10 and TSP but had durability and maintenance problems reducing its practicality. Feed modification appeared to be effective in reducing ammonia emissions   but additional data analysis is needed.  Additional research air quality research needs include improving measurement methods, developing emission and dispersion models, as well as evaluating factors affecting emissions, mitigation strategies, and technological and economic feasibility.
Harry Hoitink (OSU) noted that calculations using mass balance of nitrogen approach produce similar ammonia emissions by the birds (1.03 g/dy/bird).

Jon Rausch (OSU):  Question not audible.  Zhao responded that the belt battery facility had lower emissions but if emissions from the compost building to which the manure was transported were measured, the total may not be different.  However, the reduced concentrations of ammonia and PM10 in the belt battery building can have a positive impact on bird health.

Harold keener (OSU) asked if the producer modified its feeding program as it appears that ammonia was significantly reduced?  Zhao responded that the modifications were not adopted due to the cost.

Issues for Regulating Air Quality on Livestock Operations
Calvin Parnell, Texas A&M University

Appropriate regulation of agricultural emissions of air pollutants is essential. If the EPA and/or state air pollution regulatory agencies (SAPRA) inappropriately fine and require controls to be placed on facilities without the proper justification, the air pollution regulatory process is not functioning properly. The Federal Clean Air Act and similar legislation by state legislatures provide the enabling legislation for states to permit and enforce emissions of air pollutants.  EPA and SAPRA regulating personnel must estimate emission rates using emission factors. Many emission factors for agricultural operations are unknown and/or are not based upon sound science. The emission of air pollutants must be based upon sound science. 

Recently, three large swine operations reached a $25 million settlement with the US EPA for failure to report ammonia emissions. Since ammonia is not a “criteria pollutant” or a “hazardous air pollutant”, it is not regulated by EPA and SAPRA in a .manner similar to emissions of PM10, NOx, SO2, etc under the Clean Air Act (CAA). The settlements were a consequence of not reporting the ammonia emissions and the assumption that each of agricultural operations were emitting more than the reportable quantity of 100 pounds per 24-hour period. CERCLA commonly referred to as “Superfund” was cited as the enabling legislation. There are those who question whether ammonia from “naturally occurring” emissions from livestock facilities are appropriately regulated under CERCLA. There is no question that CERCLA and the CAA are two different laws and CERCLA is not a subset of CAA. In general, CERCLA ia a “reporting requirement” with violators subject to $27,500 per day for not reporting. In contrast, the CAA is the enabling legislation for permitting and enforcement of air pollution emissions.

Buckeye Egg:
In 2004, the US EPA fined Buckeye Egg Farm $880,598 and required the owner/operator to invest $1.4 million for controls and monitoring. The justifications for these actions were failure to obtain Title V and Prevention of Significant Deterioration (PSD) permits. The thresholds for requiring Title V and PSD permits are 100 and 250 tons per year of particulate matter less than a nominal 10 micrometers in diameter (PM10). The EPA used measured concentrations and flow rates reported by their contractor to calculate annual PM emissions.  The EPA and contractor made the following serious errors:
•    They used measured total suspended particulate (TSP) concentrations rather than PM10 concentrations to calculate annual emissions of PM10. The contractor reported particle size distributions for the Buckeye facility reported to be emitting 740 tons of PM per year. This size distribution was not used. The CAAQES analysis of the contractors reported size distribution suggested that had the size distribution been used, the facility would have been projected to emit less than 10% of the 740 tons per year of PM10 or approximately 74 tons per year. 
•    They used inappropriate flow rates through the poultry houses to calculate annual emissions. The contractor reported measured flow rates of 6,300 cubic feet per minute (cfm) per fan. EPA chose to use 14,000 to 16,000 cfm per fan operating for 365 days per year, 24-hours per day. These data were compared to the Midwest Plan Service (MWPS) for flow rates and was significantly higher. Using MWPS recommendations that varied the recommended flow rates depending upon ambient temperature, the total annual flow rate was approximately 40% of the flow rate used by EPA. Using the MWPS flow rates, it is likely that the emission rate of PM10 was 35 tons per year. 

This facility did not meet the threshold for requiring either PSD or Title V permit.!  In April, 2005, EPA fined the new owner of these facilities an additional $500,000. 

Sampler Bias:
A subcommittee of the Agricultural Air Quality Task Force (AAQTF) met with Steve Page and a large number of his staff (OAQPS, EPA @ RTP) and addressed the “over-sampling” issue with federal reference method (FRM) PM10 and PM2.5 samplers in the presence of PM emitted by agricultural sources. This is a consequence of the larger PM characteristically emitted by agricultural operations. For example, FRM PM10 samplers have the potential for an over-sampling error of 225%. This problem is even more pronounced with FRM PM2.5 samplers. The problem is associated with the use of ambient samplers at the property line of fugitive sources of agricultural PM emissions and the EPA requirement that these concentrations be less than the NAAQS.

Reactive Volatile Organic Compounds (RVOC)Gas:
Pending regulations in California will implement emission standards for reactive organic gases (ROG) or RVOC which are precursors for the formation of ozone. Ozone is a criteria pollutant (a gas regulated under the Clean Air Act).   Current research is limited and inadequate for accurately quantifying the emission rates of Reactive Volatile Organic Compounds (RVOC) emitted from livestock facilities. The concern of researchers and livestock producers is that regulations that could have a significant impact on livestock producers will be established based on emission factors that are not grounded in sound science.

Harry Hoitink (OSU) noted that there was a history of problems at some Ohio layer facilities and emissions, while only part of the problem, provided the means to implement regulatory authority.  Parnell responded that although there were documented management problems at some Buckeye facilities, including ongoing fly and odor complaints, the US EPA was initially involved due to water quality issues.  It is important that any “bad actor” in livestock production be subject to consequences under the appropriate legislation and that good science be used.  If measurements that are neither accurate nor valid are used to impose fines or restrictions, the precedents set will have long term repercussions. 

Kevin Elder (ODA) asked if the methodology/data used by the US EPA to analyze PM10 emissions at Buckeye is still being used.  The Ohio EPA did not agree with those findings but it seems that it is very difficult to correct the problem.  Parnell agreed. 

Maurice Watson (OSU) noted that a California study cite that highways are big contributors to PM2.5 (2.5 microns).  Parnell agreed that those findings had been made based on measurements along California highways.

Parnell discussed concerns regarding the US EPA proposed NAAQS for PMcoarse (between 2.5 and 10 microns).   The particle size distribution (PSD) for PM emissions from agricultural areas is significantly different compared to those from urban/industrial areas; the mass mean diameter (MMD) for PM from urban areas is 5.7 microns and from rural areas is 20 microns.  Research at the CAAQES indicates that samplers that measure PM10 concentrations can be measure concentrations of up to 300% higher for large MMD compared to those with MMD of 10 microns or less. The sampling error needs to be accounted for before NAAQS thresholds for PMcoarse are established. 

Mike Lilburn (OSU) asked for recommendations to address the problem in poultry facilities where dry conditions increase the potential for greater emissions of PM but wet conditions increase the potential for ammonia emissions.  Parnell responded that it is a problem and requires careful balancing and management.  Currently the CAAQES focuses on PM emissions as they are regulated while ammonia emissions are not.

Diane Borger (OSU) noted that it is disconcerting that the US EPA Region V is still using the data used in the Buckeye Egg decision which is not accurate.  How do you instigate change?  Parnell responded that there have been successes for changing emission standards for cotton gins.  It requires both education and good science that produces valid data.

The AFO Air Quality Agreement: Background, Implementation and Impacts
Sharon Nizich, U.S. Environmental Protection Agency

A National Academy of Science study of air emissions from animal feeding operations (AFO), conducted at the request of the USDA and US EPA, found that no reliable emission factors exist for these facilities.  In response to the study and public concerns, the EPA and industry representatives developed the AFO Air Quality Agreement with the goals of monitoring and evaluating emissions, promoting consensus on methodologies for estimating emissions, and ensuring compliance with federal regulations intended to reduce air pollution.  As of December 2005, over 6700 farms have been entered into the agreement database, including 479 in Ohio.  Monitoring of particulate matter, hydrogen sulfide, volatile organic compounds and ammonia from selected facilities that represent different species and regions is expected to begin in the spring of 2006 and continue for two years.  If emissions of hydrogen sulfide or ammonia are found to be greater than 100 lbs/day, those facilities will be required to report emissions under CERCLA* and EPCRA**.  Although these regulations do not require permitting and have no associated costs, environmental groups have been known to sue for non-reporting.  For facilities with emissions of volatile organic solids, nitrogen oxides or particulate matter greater than the thresholds set in the Clear Air Act (CAA), permitting could be required with an expected 3 to 5 year phase-in for implementing emission control practices.  The CAA thresholds vary for different locations depending on emissions from all sources.  The long term goal is to develop a process-based emissions model easily used by the farming operation to estimate emissions, rather than monitoring every farm.

*Comprehensive Environmental Response, Compensation and Liability Act
** Environmental Planning and Community Right-to-Know Act

Mike Lilburn (OSU) questioned why administration of the agreement has  been contracted to John Thorne, a non-scientist, rather than the EPA.  Nizich noted that, while she was not involved in that decision, the
EPA’s role is to collect data for quality assurance and validation, not study administration.  For the monitoring study, EPA will be more involved than usual in conducting site evaluations.

Lilburn asked why some facilities, such as the National Turkey Federation and National Chicken Council, chose not to participate in the agreement.  Nizich responded that, legally, the agreement was structured
so that those signing had to pay a civil penalty upfront in order for the agreement to be legally binding.  Although the agreement clearly states that there is no assumption of guilt on the part of the participants, m many saw it as an admission of guilt and were not willing to sign.

David White (Ohio Livestock Coalition) noted that many in the poultry industry were more concerned that the agreement did not allow for appeals or challenges of the data collected.

White asked if the 100 lbs/day threshold was a one time emission or over a period of time.  Nizich responded that reporting is needed for a one-time emission; however, a report only needs to be filed once, not daily.  A follow up report is to be filed one year later, but that is the end of the required reporting.

White asked the status of challenges to the EPA’s right to have developed and implemented the agreement.  Nizich noted that several challenges have been consolidated and a decision is expected from the Circuit Court in the next few months.

Mike Monnin (NRCS) asked how many of the 479 farms that signed up in Ohio will participate in the monitoring study.  Nizich replied that the farms in the study are unknown at this time.  It is expected that Al Heber from Purdue University will be selected as the Science Advisor (SA) for the monitoring study.  The SA is responsible for selecting the Principal Investigators (PI) who will conduct the study at specific sites, which are required to be within in a 2-hour drive of the PI.  It is expected that PIs will be University agricultural air quality experts.

Lingying Zhao (OSU) asked how research on agricultural air quality currently funded by the USDA will impact the study.  Nizich responded that relevant data will be included in the monitoring study.

Zhao asked if the study to research mitigation technologies will be at the same farms as the monitoring study.  Nizich replied that mitigation studies are expected to be conducted on some of the same farms, although are not covered under the AFO Consent Agreement.

Lilburn asked how variations in seasonal discharges, such as increased particulate matter while planting during a dry season, will impact regulations.  Nizich responded that regulations will vary depending on each state’s implementation plan (SIP).  There is a possibility that tillage practices could be affected but one should consult with the state air quality agency to see how agricultural tillage is accounted for in the SIP.  Currently there are no PM10 (particulate matter less than 10 microns) non-attainment areas in the state of Ohio.  However, farming operations should consult with their state agricultural contacts to stay abreast of Ohio regulations.

Wet Scrubbers to Control Ammonia Emissions from Animal Buildings
Roderick Manuzon, Ohio State University

Although ammonia emissions are not regulated in the U.S., it is a precursor of PM2.5 (particulate matter with 2.5 micron diameter or lower), which is a criteria pollutant regulated under CERCLA* which limits emission to 100 pounds/day.  Concerns that high levels of ammonia emitted from large poultry facilities may result in PM2.5 levels exceeding the standard has increased interest in using scrubber to remove ammonia before air is exhausted from a building.  This study used a spray- type wet scrubber designed to use a small amount of water, have minimal impact on airflow and reduce ammonia emissions as well as particulates.  The effectiveness of the scrubber increases as the mass transfer coefficient increases, droplet size decreases and scrubber height increases.  The mass transfer coefficient is affected by the acidity of the solution being sprayed as it increases its reactivity.  Smaller droplets increase surface area while the scrubber height affects contact time of the solution with the emitted air. The nozzle type and operating pressure, scrubbing liquid acid concentration, number of nozzles, screens to separate droplets and stages through which the emissions moves were optimized for ammonia scrubbing efficiency using a half scale scrubber prototype.  Although theoretical computations indicated that a multi-stage scrubber would improve removal of ammonia, the data were significantly lower than expected due to the interaction of droplets between stages.  To mitigate the problems, screens were used to separate the droplets but they decreased the air pressure below acceptable limits and the flow configuration was changed. The optimal system used a mixed-flow design with two counter flow nozzles in the lower stage and two co-flow nozzles in the higher stage with a single screen in between the stages. Additional research is recommended to evaluate the effect of increasing gas retention time inside the scrubber and of reducing droplet size within the multi-stage chambers on reduction of ammonia.

* Comprehensive Environmental Response, Compensation and Liability Act

Harry Hoitink (OSU) noted that he had heard of a system that uses horizontal tubes with a central axle with a disc perforated with small holes.  Air flows through the tubes and the disc turns, emitting the liquid into the tube.  However, documentation of the effectiveness of the system is not available.  Manuzon suggested that it may be similar to a cyclonic wet scrubber.  Lingying Zhao (OSU) noted that the challenge in agriculture is the need to process large volumes of air.  Large changes in pressure are not acceptable as it affects affordability.