Pork Industry Air Quality Research
07/16/07

Pork Industry Air Quality Research & Extension Needs & Priorities and Strategies to Resolve Them

On April 12th and 13th 2007, the National Pork Board and the U.S. Pork Center of Excellence jointly sponsored an Air Quality and Odor Research Meeting. This one and one-half day meeting was held at the offices of the National Pork Board in Clive, Iowa.  Persons invited to attend this meeting included individuals directly involved in research related to addressing air quality and odor control from swine operations; State Pork Association Executives; a representative of the National Pork Producers Council; members of the National Pork Board’s Environment Committee and representatives of the U.S. Pork Center of Excellence. 

Thirty-six (36) people attended this meeting including: twenty-one (21) individuals involved directly in swine related research efforts three of whom also serve as science advisors to the National Pork Board’s Environment Committee, five (5) pork producer members of the National Pork Board’s Environment Committee, four (4) State Pork Association Executives, one (1) representative of the National Pork Producers Council, three (3) staff from the U.S. Pork Center of Excellence and two (2) staff from the National Pork Board’s Science & Technology Department. 

A list of attendees is in Appendix 1.

The purpose of this meeting was to foster a sharing of information and thorough discussion among attendees in order to:

• Identify air quality research underway or already completed on the causes and control mechanisms for emissions of odor, ammonia, hydrogen sulfide and particulate matter from swine production operations.
• Identify what is known as a result of the research identified and that can be developed into informational materials and programs by the National Pork Board, the U.S. Pork Center of Excellence or others to inform and benefit pork producers. 
• Identify what information gaps remain and questions that still need to be answered by further research efforts not known to be currently in progress.
• Work to form a consensus on priority areas to be researched for consideration by the National Pork Board Environment Committee or the U.S. Pork Center of Excellence in targeting future research investments and efforts.
• Work to identify opportunities for soliciting research funding from external sources to better leverage the National Pork Board research investment.
• Investigate the feasibility of a Cooperative Agricultural Project (CAP) on air quality and work to construct a proposal for submission to USDA/CSREES

The meeting was formatted to stimulate thought and foster collaborative exchange among the participants and organized around the three primary subject areas of particulate matter, gasses focused on hydrogen sulfide and ammonia, and odor.  A copy of the meeting agenda is in Appendix 2

The expected end products from this meeting included

• Identification of producer informational / educational materials that could / should be developed based on available research.
• A recommended priority list for development of producer educational and informational materials based on available research.
• Identification of persons(s) best able to develop identified informational & educational materials.
• Identification of research efforts needed to fill gaps in information.
• A recommended priority list for identified research needs.
• The beginning of a CAP proposal with assignments for completion.

Particulate Matter

• We know the nature and sources of particulate matter at production operations.  They include dusts generated from animal feeding and feed storage and transfer, skin dander from the animals, and dried fecal materials.  Micro-organisms can also be a contributor to particulate matter. Chemical reactions can convert gas emissions and condensates such as ammonia from manure storage facilities into particulate matter as well.  Particulate matter can also be deposited on swine operations from off-site sources such as neighboring farm fields, gravel roads and other sources which can then be re-entrained into the air through on-site operations.
• We know that 40% of fine dust particles are protein from feed, dander and micro-organisms.
• We have limited data and knowledge on the relative contribution of individual sources to the total particulate matter mix.
• We have limited data and knowledge about the mass distribution of particulate emissions from swine operations by size range (TSP, PM10, & PM2.5)
• We have limited data and knowledge on the quantity of particulate matters emitted from swine housing.
• We have limited knowledge on sampling methodologies for particulate matters in swine facilities but question methodologies for monitoring ambient air impacts from swine operations used to date.
• We know that particulate matters can serve as carrier transport mechanisms for odor, ammonia and biological materials.
• We know that, in general, particulate matters have been shown to have human health impacts at given exposure levels.  These human health impacts are much better defined for occupational exposures for workers at swine operations than they are for potentially exposed public external to the operation.
• We have knowledge on methods to mitigate dust emissions from swine operations that include:
• Management practices such as periodic cleaning and controlling dust within the buildings and the ventilation units, minimizing drop heights on automatic feeders, cleanup of spilled feeds, etc:
• Oil sprinkling to suppress in-barn dust.
• Feed management practices such as addition of fat to the feed, using pellet feeds or liquid feeding systems.
• Employing biofilters on ventilation system exhaust fans
• Employing vegetative shelter belts at strategic points external to the barns for the suppression and reduced site visibility.
• Transferring industrial particulate emission control technologies such as cyclones, electrostatic precipitators or wet scrubbers to swine operations

Gases

• We know that noxious and/or odorous gases including ammonia (NH3), hydrogen sulfide (H2S), and volatile organic compounds (VOCs), can be generated from biodegradation of manure/waste.
• We know that greenhouse gasses (GHGs); including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), result from animal respiration and biodegradation of manure/waste.
• We know mitigation technologies or BMPs have been shown to be effective or potentially effective in reducing gaseous (and odor) emissions. However, on-farm demonstrations/evaluations are lacking and should be carried out to increase confidence in the results (e.g., 3 paired commercial houses comparison, as recommended by Danish scientists). The promising or potential mitigation BMPs include:
• Biofilters (second generation)
• Exhaust chimneys
• Physical and/or vegetative windbreaks (barrier walls & tree windbreaks)
• Manure storage covers (e.g. straw, synthetic permeable & non-permeable)
• Diet manipulation (additives and/or low crude protein)
• Timely manure incorporation at time of land application
• Anaerobic digesters (management issues, mismatch between peak production and need for biogas)
• Further on-farm demonstrations of these and new potential BMPs should address the economics, practicality, and cost effectiveness for various levels of emission reduction. In some cases partial (say, 20%) (vs. drastic, say, 80%) reduction may be all that is needed to achieve the desired result, e.g., meeting the allowable emission quantity.  One way to further demonstrate the viability of the BMPs is to partner with NRCS that offers funds for conducting such field demonstrations (e.g., EQIP funds).
• We have limited data and knowledge on Emission Factors from swine operations.Approximate ammonia (NH3) emission factors associated with certain schemes of swine housing, manure storage and land application, or manure management trains were established by U.S. EPA, based on limited research data.  Some ammonia emission factors for swine (i.e., outdoor lot system) were developed using emission factors for feedlot cattle as the reference.  Hydrogen sulfide emission factors are even weaker.  Emission factors for greenhouse gasses are nearly non-existent for U.S. swine production conditions.  Some new barn–level emission factors data on ammonia and hydrogen sulfide for U.S. grow-finish (pull-plug & deep-pit systems) farrowing, and gestation operations have recently been collected. Subject to further verification, there seem to be appreciable discrepancies between the newly collected emission factor data and those established/used by EPA.
• We know that more baseline data on gaseous (ammonia, hydrogen sulfide, & carbon dioxide) emissions from selected U.S. swine housing and manure storage systems are to be collected under the National Air Emissions Monitoring Study being conducted by certain sectors of the animal industry, including swine feeding operations, in cooperation with and under oversight from EPA. The new emission factors data are expected to be available in 2011.
• We know that considerable progress has been made toward evaluating the performance of various measurement technologies or instruments for quantification or characterization of gaseous emissions from housing and manure storage as well as ambient concentrations (i.e., ambient air quality). An example of the effort is the EPA Environmental Technology Verification (ETV) program. The gases measured with the instruments include NH3, H2S, VOC, CH4, N2O, CO2, and SO2.
• We know that research toward finding new cost-effective mitigation practices and technologies continues in the U.S. and Europe.

Odors

• We know that of the 400 or more odorants identified from swine manure, p-cresol is the primary contributor to the offensive odor associated with swine manure.
• We know that diets fed to swine can impact odors positively or negatively. It is also known that diet can impact odors through storage and land application as well.  This area includes nutrients fed and the efficiency of utilization of these nutrients so they do not end up as precursors for some negative odor.
• We know that we can objectively measure and quantify odors using sensory and chemical techniques. When using chemical techniques, we are really analyzing gases or chemicals rather than odors per se. The sensory techniques are very sophisticated with objectivity of trained sensory panels.
• We know that there are current stock values for emission factors. These basic values can help with an assessment of odor generation in a pork operation.
• We know how to evaluate current treatment technologies using headspace concepts.
• We know some best management practices that can be recommended to pork producers with the best opportunity to reduce odors in their operation whether from the building, manure storage, or manure application.
• We know something about the effectiveness of current technologies:
• We know that filtering the ventilation air from hog production systems using biofilters can reduce odors by up to 90%. We know some of the materials that work in this system and we know that the material needs to be kept wet.
• We know that manure storage covers can help alleviate odors whether they are natural or synthetic, permeable or impermeable.
• We know that vegetative buffers or windbreaks may help mitigate odors and may provide other benefits such as dust control.
• We know that technologies for application of manure are variable in odor production but that timing of application is important. Even though we need more definitive information regarding the variable nature of odor production associated with land application, we do know that certain application approaches have superior results compared to others in decreasing odors.  Of these alternative application procedures, injection of manure directly into the soil is the best way to reduce the odors associated with application.

Suggested Priorities for Transferring Known Research and Information:    

Particulate Matter    

• General knowledge of PM - What are the potential impacts of PM
• How particulates serve as odor transport mechanism
• Potential health impacts of particulates on workers
• EPA regulated primary pollutants
• General information on particulate matter (measurement methods
• Utilization of personal protective equipment for workers to minimize exposure.
• Feed  management practices to control particulates
• Fat addition
• Pelletizing
• Liquid feeding
• Feeder covers
• In-building management practices to control particulates
• Fan cleaning in such as manner as to not simply relocate dust
• Building cleaning for dust suppression (collection of spilled feed etc.)
• Dust suppression by sprinkling (oils, water, other liquids)
• Electrostatic Precipitators - ESP (limited data on swine)
• Information on exhaust air treatments for particulates control
• Bio-filters (no quantification of PM reduction to date)
• Wet scrubbers (technology transfer from industry)
• Cyclones (technology transfer from industry)

Use of vegetative shelterbelts for control of particulates although there is a question whether enough performance data exist on the amount of particulates reduction to transfer this technology.

Data on in-house concentrations of particulates and emissions by swine facility type.

Gases

• Newly collected EF data on NH3 and H2S for gestation, farrowing and growing-finishing (pull plug or deep pit) swine operations. Implications of EF with regards to reportable quantity of NH3 and H2S under CERCLA.
• New research findings as presented at scientific conferences and/or in refereed journal articles should be synthesized and added to the potential mitigation BMP list.
• Mitigation BMPs (those listed under Section I.B. – Gases) that have been shown to be promising or effective in laboratory or some commercial production settings field production conditions – advantages and limitations of each BMP.
• Downwind dispersion of noxious gases as predicted by various models. How the models may be used to assist in siting of new production facilities and/or understanding the fate/transport of the gases in the atmosphere.
• Measurement techniques for quantification of source emissions and ambient air quality concentrations.

Odors

• Of the known ways to alleviate or reduce the presence of odors from swine production units, from storage of swine manure or from land application of swine manure, the following represents a prioritized list of the top areas that should be addressed for the benefit of pork producers wanting to apply the technology.
• The first idea that a pork producer should consider in this arena is to adopt a systems approach to dealing with odors from whatever source. A holistic look at the operation and solutions to the problems using some of the components of a HAACP type approach using critical control points and recording of deviations from the expected is in order. Pork producers have the opportunity to utilize a suite of tools to address odor control in the operation. Some examples of this wide realm of tools follow.
• It is important that siting of buildings consider prevailing wind direction, traffic patterns, pig flow, load outs, manure management, and neighbors among other things. While the science is not perfect in this area, a lot is known and can be conveyed to producers involved in construction or remodeling of facilities.
• Much more work needs to be done on diet manipulation in regard to efficient utilization of nutrients which affects manure output, the components of the diet which affects odor production, and use of additives which can help control odors in waste produced. On the other hand, much is already known on the subject which can be incorporated immediately to help with odor control.
• Building type is very important and there are some new ideas being tried in this facilities area that have been shown to have a real impact on odors. One is the system being utilized at Michigan State University and being duplicated at the swine breeding farm at Iowa State University. It involves separation of the liquid and solid components of the manure almost immediately before they ever get mixed. It is known that some of the odors are a result of the reactions occurring after mixing of these two components.
• More is known about biofilters than many other technologies. It is known that they are very effective although the exact size, the amount of moisture necessary for wetting, the timing of additions of material, the best material to use, etc. are still areas to be discovered.
• Manure storage covers whether of natural materials such as straw or synthetic materials such as permeable or non-permeable materials are known to be effective. In addition, the limitations and costs of each method are known necessary to calculate a return in air quality improvement for the investment made.
• Vegetative buffers or windbreaks are known to work to absorb or disperse odors, but it is not known exactly how they work and it is difficult to quantify the benefit, but still, the practice represents one of the tools available for producer use in odor control.
• The rapid or immediate incorporation of manure is known to be beneficial in controlling odors. Injection of swine manure captures the odors in the soil as does tillage after surface application.

What We Don’t Know (Identified Research Needs):

Particulate Matter

• Data on ambient particulate matter concentrations in rural areas
• Information on impact of swine facility particulate matter on receptors (other people) (magnitude of contribution from swine facilities as fraction of particulate matter concentration at the receptor location).
•    Mass contributions and exposure
• Linkage to health impacts
• Consistent, accurate and generally accepted particulate matter sampling methodology for swine housing (i.e. methods that work in high concentrations and with the size distributions found in swine houses)
• Evaluation of existing sampling methods
• Development of new methods suitable for swine housing
• Properties of PM from swine housing
• Complete size distribution data on particulate matter from swine facilities
• PM density data by particle size distribution
• “Fingerprinting” of PM from swine facilities with a tracer
• How much viable (biologically active) particulate matter is transported from swine facilities to receptors (workers, surrounding community, animals)
• Chemical speciation of particulate matter
• Better defined methods for swine particulate matter
• Data
• Biological speciation of particulate matter
• Better defined methods for swine PM
• Data
• Economics of existing swine PM mitigation methods
• Development of PM mitigation methods for swine systems
• Technical feasibility studies of industrial PM mitigation methods that could be transferred to swine systems
• Development of “smart” swine PM mitigation systems that operate only when needed (i.e. only when a receptor would be negatively impacted)
• The role of dust as an animal disease vector in-house

Gases

• Quantify cause-effect relationships between gaseous emissions and ambient levels vs. community and ecological health
• Quantify/understand fate and transport of gases in the atmosphere, especially with regards to their roles as precursors to fine particulate matters (i.e., PM2.5)
• Investigate alternative, more reliable measurement methodologies for ambient air quality monitoring
• Measure emissions of other gases besides NH3, H2S and VOCs, i.e., greenhouse gases
• Conduct cost-benefit analysis of mitigation technologies using a holistic approach, incorporating animal genetics, nutrition, building, manure storage, and land application aspects. This is especially the case when only dilution (partial reduction) vs. treatment (major reduction) may be needed.
• Establish and regularly update a clearinghouse on state of the science, i.e., documented research findings, ongoing research, demonstration, and application
• Quantify emissions from naturally ventilated barns
• Validate/refine dispersion/setback models by collecting more relevant data in the field
• Better understand the operational mechanisms of various mitigation techniques. Does one technique (e.g., vegetative windbreak) work for all gases or only certain ones and why?  
• Explore alternative feeds/additives that may lead to reduced gaseous (as well as odor) emissions, e.g., DDGS
• Determine the incentives for technology adoption

Odors

• Faster, real time, more accurate methods are needed to measure and detect odors
• Before odors are generated, the focus should be on diet manipulation, new biochemical and microbiological methods to reduce p-cresol, a study of new additives and more work on new building types. Diet manipulation involves enhancing nutritional efficiency connection with environmental concerns, targeting odorous compounds such as how Glycerol feeding impact on odorous compounds, and biochemical/microbiological methods to reduce p-cresol, etc. which involves further HRP (horseradish peroxidase) studies: genetically engineered microorganisms to change odorants to take away odors. The new additives study would be an update of the 2000 study on the same subject, and the new studies on new building types is needed.
• To control emissions, the focus should be on ventilation management which includes pit ventilation, new cooling to alleviate the need for maximum airflow, Chimneys which have mixed ideas about effectiveness, the use of biofilters which should involve investigations on media and configurations, new building systems which can reduce odors, and energy generation which includes a systems evaluation of digesters and gasifiers.
• Addressing post emissions reductions, attention should be given to vegetative buffers, more data on dispersion approaches such as terrain effect, new building systems, and improved manure application approaches such as surface, incorporation, and additives. 

Prioritized Listing of Research Gaps:

Particulate Matter

• Information on impact of swine facility PM on receptors (workers & surrounding community)
• Magnitude of contribution from swine facilities as fraction of PM concentration at the receptor location).
• Mass contributions and exposure
• Exposure linkage to health impacts of surrounding community
• Exposure linkage to worker health
• Economics & practicality of existing swine PM mitigation methods
• Properties of PM from swine housing
• Complete size distribution data on PM from swine facilities
• PM density data by particle size distribution
• Consistent, accurate and generally accepted PM sampling methodology for swine housing (i.e. methods that work in high concentrations and with the size distributions found in swine houses)
• Evaluation of existing sampling methods
• Development of new methods suitable for swine housing
• Development of “smart” swine PM mitigation systems that operate only when needed (i.e. only when a receptor would be negatively impacted)

Gases

• Quantify cause-effect relationships between gaseous emissions and ambient levels vs. community and ecological health
• Quantify/understand fate and transport of gases in the atmosphere, especially with regards to their roles as precursors to fine particulate matters (i.e., PM2.5)
• Conduct cost-benefit analysis of mitigation technologies using a holistic approach, incorporating animal genetics, nutrition, building, manure storage, and land application aspects.

Odors

• Diet manipulation to reduce odorants or their precursors
• New innovative biochemical, microbiological, & genomic methods to reduce odorants
• Options for controlling odors
• New/modified building & ventilation systems
• Vegetative buffers
• Etc.

Listing of Potential Funding Sources to Fill Research Gaps:

• USDA (NRCS-EQIP & CIG and ARS-NRI)
• USEPA
• USDOE
• NIOSH
• NIH (community health) – need partnerships for success
• Equipment manufacturers (on the go manure analysis, ventilation)
• Carbon/Emission credit entrepreneurs (VOCs and PMs also)
• Credit Banking (baseline is 1999)
• Pork Checkoff Research Funds

What Happens From Here

The results of the discussions at this meeting will be prepared in a written report document and distributed to attendees for review, comment and edit and the edited final copy provided to all attendees.

Copies of the revised and edited final report document will be provided to the relevant National Pork Board Technical Committees for their consideration as they prepare solicitations for and make funding decisions on future research investments and develop technology transfer materials for the benefit of pork producers and the public.

In order to build on the networking process among scientists started at this initial meeting, and in recognition of the dynamic and changing nature of environmental considerations, issues and solutions it was consensus that a similar follow-up meeting be held on an annual basis to review, update and revise this baseline document.

It appears desirable to pursue a Coordinated Agricultural Project grant for coordinated air quality research that would address the three major aspects of air quality issues (in-building worker and animal health impacts, external to building environmental impacts and external to building public health impacts) and mitigation strategies.  The US Pork Center of Excellence will take the lead in facilitating and coordinating these efforts