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Animal Ag Air Pollution Overview

Air pollution, and specifically PM2.5 air pollution, is the number one environmental cause of human deaths in the U.S.[1]

Globally, PM2.5 air pollution is the environmental factor responsible for most human deaths.[2] In fact, of all causes of premature death, it is considered the largest or 2nd largest.[3-5]

 

  1. Tessum, C. W., et al., (2019). Inequity in consumption of goods and services adds to racial–ethnic disparities in air pollution exposure. PNAS, 116(13), 6001–6006, p. 6001. [“Fine particulate matter (PM2.5) exposure is a major health risk factor in the United States, responsible for 63% of deaths from environmental causes and 3% of deaths from all causes.”]      
  2. United Nations Environment Programme (2021). Actions on Air Quality: A Global Summary of Policies and Programmes to Reduce Air Pollution. Nairobi, p. 13. [Air pollution is “The single greatest environmental risk factor for premature death globally.”]
  3. Brauer, M., et al., (2024). Global burden and strength of evidence for 88 risk factors in 204 countries and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021. The Lancet, 403(10440), 2162-2203. [“Among the specific risk factors analysed for this study, particulate matter air pollution was the leading contributor to the global disease burden in 2021.” at p. 2162 & Figure 2]
  4. Health Effects Institute (2024) State of Global Air 2024. Special Report. Boston, MA. [Air pollution trailing only high blood pressure, with 8.1 million total deaths in 2021. Of total air pollution deaths, 7.8 million due to PM2.5. at p. 3 & 13, Figure 9]
  5. This section treats air pollution separately from climate change. Naturally, GHG emissions are a form of air pollution, and some gases drive both pollution and climate change. Our focus on these pages is on regional and national air quality apart from climate change.

Air pollution is one of the largest negative externalities of U.S. animal ag. A number of researchers have documented the damages coming from animal ag:

The work in this area is focused heavily on human health. The impacts of air pollution from animal ag (or even all agriculture) on forests, oceans, wildlife, and ecosystems are less often assessed.[7,8]

The impacts on farmed animals, the ones most severely affected, are investigated with a focus on production value rather than the suffering inherent in living in severely polluted air environments.

 

  1. Tschofen, P., et al., (2019). Fine particulate matter damages and value added in the US economy. PNAS, 116(40), 19857–19862. [See, Table 1 “Animal production and aquaculture – 2.0 GED/VA” (Gross External Damages/ Value Added)]
  2. Domingo, N. G., et al., (2021). Air quality–related health damages of food. PNAS, 118(20), e2013637118, p. 2.
  3. Thakrar, S. K., et al., (2020). Reducing Mortality from Air Pollution in the United States by Targeting Specific Emission Sources. Environmental Science & Technology Letters, 7(9), 639–645, Figure 3. https://doi.org/10.1021/acs.estlett.0c00424
  4. Paulot, F., & Jacob, D. J. (2014). Hidden cost of US agricultural exports: particulate matter from ammonia emissions. Environmental science & technology, 48(2), 903-908. [Calculation based on Table 1: Total health costs = $36 billion. Share of NH3 emissions for livestock = 165 GgN/295 GgN = 56%. (.56 * $36B) = $20.2B livestock health costs / $10.1B livestock gross profits = ~2 times. $20.2B / $3.4B livestock net profits = ~6 times]
  5. Hill, J., et al., (2019). Air-quality-related health damages of maize. Nature Sustainability, 2(5), 397-403. [Corn 4,300 deaths (p. 397) PM2.5 health damages $39 billion / $4.9 billion GHG damages = ~8 times (p. 398)]
  6. Goodkind, A. L., et al., (2023). Managing nitrogen in maize production for societal gain. PNAS nexus, 2(10), pgad319, Abstract. [“We find that the monetized health and environmental costs to society of current maize nitrogen management practices are six times larger than the profits earned by farmers. Air emissions of ammonia from application of synthetic fertilizer and manure are the largest source of pollution costs.”]
  7. Guthrie, S., et al., (2018). The impact of ammonia emissions from agriculture on biodiversity. RAND Corporation and The Royal Society, Cambridge, UK. [“Firstly, it must be noted that there is very limited evidence on the effects of ammonia on animals and wider ecosystem function.”]
  8. Krupa, S. V. (2003). Effects of atmospheric ammonia (NH3) on terrestrial vegetation: a review. Environmental pollution, 124(2), 179-221. p. 181 [“Natural and semi-natural ecosystems, as well as forests must be expected to be severely at risk from the current amount of N deposition. Agricultural crops appear to be the only systems not negatively influenced at present, since high productivity and turnover prevent the accumulation of N.”]             

There are hundreds of air pollutants from animal ag.[1,2] One study identified a total of 331 different gases and volatile organic compounds (VOCs) at pig factory farms in North Carolina.[3] That’s too many gases to name and far too many to understand.

We focus primarily on the effects of ammonia (NH3) because it is by far the most damaging.

 

  1. Aneja, V. P., et al., (2009). Effects of Agriculture upon the Air Quality and Climate: Research, Policy, and Regulations. Environmental Science & Technology, 43(12), 4234–4240, p. 4236. [“Animal production results in emissions of hundreds of identified VOCs (volatile organic compounds).”]
  2. Ni, J. Q., et al., (2012). Volatile organic compounds at swine facilities: A critical review. Chemosphere, 89(7), 769-788. [“More than 500 VOCs have been identified.” Abstract]
  3. Schiffman, S. S., et al., (2001). Quantification of odors and odorants from swine operations in North Carolina. Agricultural and Forest Meteorology, 108(3), 213-240.

In volume, importance, and damage, ammonia (NH3) which is created from excess nitrogen is the central air pollutant of animal ag.[1-4] Of all ammonia emissions in the U.S., most originate from animal ag.[5]

Ammonia is considered a precursor gas, which can create PM2.5.. And PM2.5 is by far the largest cause of human health-related damage from air pollution.[6,7]

On factory farms, high levels of ammonia can be damaging to farmed animals and workers.[8] On a regional and national level its transition to PM2.5 is particularly damaging to human health.

 

  1. U.S. EPA (2024) 2020 NEI Supporting Data and Summaries – Data Queries for Sector Summaries.
    [Total nitrous oxide from all agriculture at ~1.1 million tons versus ~5.5 million tons ammonia (mostly from animal ag)]
  2. Rotz, C. A., et al., (2014). Ammonia emission model for whole farm evaluation of dairy production systems. Journal of environmental quality, 43(4), 1143-1158, p. 1143. [“Emissions (from animal agriculture) include greenhouse gases, volatile organic compounds, and specific toxic compounds, of which ammonia (NH3) is the most important.”]
  3. Hill, J., et al., (2019). Air-quality-related health damages of maize. Nature Sustainability, 2(5), 397-403. [Report estimates the PM2.5 pollution costs of corn production (the primary animal feed) at ~8 times the GHG damages of corn production.]
  4. Giannadaki, D., et al., (2018). Estimating health and economic benefits of reductions in air pollution from agriculture. The Science of the Total Environment, 622–623, 1304–1316, p. 1305. [“The main pollutant from agricultural activity is ammonia (NH3)…”]
  5. U.S. EPA (2024) 2020 NEI Supporting Data and Summaries – Data Queries for Sector Summaries. [Query: National/Ammonia NH3/Livestock Waste (49.2%), fertilizer application (33.5%), agricultural field burning (2.7%) of total (5,482,484 tons). Of the 36.2% due to crop production, we estimate at least half is from feed crops.]
  6. Wyer, K. E., et al., (2022). Ammonia emissions from agriculture and their contribution to fine particulate matter: A review of implications for human health. Journal of Environmental Management, 323, 116285–116285, p. 1. https://doi.org/10.1016/j.jenvman.2022.116285  [“There is currently a chain that exists between NH3 emissions, the formation of PM2.5, and the subsequent impacts that this PM2.5 has on human health.” (See, pp. 5-6 for details regarding those transformations)]
  7. Tessum, C. W., et al., (2019). Inequity in consumption of goods and services adds to racial–ethnic disparities in air pollution exposure. PNAS, 116(13), 6001–6006, p. 6001. [“Fine particulate matter (PM2.5) exposure is a major health risk factor in the United States, responsible for 63% of deaths from environmental causes and 3% of deaths from all causes.”]
  8. Naseem, S. & King, A. J. (2018). Ammonia production in poultry houses can affect health of humans, birds, and the environment—techniques for its reduction during poultry production. Environmental Science and Pollution Research International, 25(16), 15269–15293, p. 15273.      

Initially, ammonia pollutes at the factory farm and local community level. Then, it pollutes on a regional or national level after creating PM2.5. Since nitrogen is highly reactive, it continues to form various compounds, circulating between air, water and soil.

Most air-borne ammonia is short lived and will be deposited in a day or two within 2 or 3 miles of its source.[1,2] Although at the factory farm level, ammonia hurts animals and workers and is a major component of odors in local communities.[3,4] 

In a second stage, some portion of ammonia reacts with aerosols to create PM2.5 which can drift, creating damage hundreds or even a thousand miles or more from the source.[5,6] Human health damages are well documented. Atmospheric deposition onto terrestrial and aquatic ecosystems causes the degradation of plant communities (including forests) and the eutrophication of waterways.[7]

There is a third stage of ammonia pollution, much less predictable and harder to study. Escaped nitrogen in any form, including ammonia, continues to react with other compounds on a long journey of environmental and health damages, moving from one ecosystem to another. This is known as the nitrogen cascade.[8] The eventual impacts include: biodiversity loss, forest decline, acidification of surface waters, hypoxia of coastal waters, harmful algal blooms, and premature human deaths.[9]

About a third of the ammonia that escapes into the environment yearly is advected beyond the U.S “to other nations or to the global atmospheric or ocean commons.”[10]

 

  1. Krupa, S. V. (2003). Effects of atmospheric ammonia (NH3) on terrestrial vegetation: a review. Environmental pollution, 124(2), 179-221, p. 181. [Ammonia lifespan of several hours to perhaps 1 to 4 days and a reach of ~.5 to 3 or 4 miles. PM2.5 assumed lifespan of about a week.]
  2. Nair, A. A., & Yu, F. (2020). Quantification of Atmospheric Ammonia Concentrations: A Review of Its Measurement and Modeling. Atmosphere, 11(10), 1092, p. 2. [“While ammonia itself has a very short atmospheric lifetime of a few hours to a day owing to rapid deposition and particle uptake, its particulate forms too have relatively short atmospheric lifetimes of under a week…”]
  3. Naseem, S., & King, A. J. (2018). Ammonia production in poultry houses can affect health of humans, birds, and the environment—techniques for its reduction during poultry production. Environmental Science and Pollution Research International, 25(16), 15269–15293, p. 15274.
  4. Cao, T., et al., (2023). Control of odor emissions from livestock farms: A review. Environmental Research, 225, 115545. [“Ammonia (NH3) is the main component of odor…”]
  5. Goodkind, A. L., et al., (2019). Fine-scale damage estimates of particulate matter air pollution reveal opportunities for location-specific mitigation of emissions. PNAS, 116(18), 8775-8780. [“We find that 33% of damages occur within 8 km of emission sources, but 25% occur more than 256 km away…”]
  6. Aneja, V. P., et al., (2008). Ammonia assessment from agriculture: US status and needs. Journal of Environmental Quality, 37(2), 515-520. [With a lifespan of about 1 to 15 days, “ammonium aerosols might travel as far as 2500 km…”]
  7. Behera, S. N., et al., (2013). Ammonia in the atmosphere: a review on emission sources, atmospheric chemistry and deposition on terrestrial bodies. Environmental Science and Pollution Research, 20, 8092-8131, pp. 8121–8124, p. 8108. [“After particulate formation and with the advantage of atmospheric lifetimes of the order of 1–15 days, NH4 salts have the tendency to be transported and deposited at larger distances from emission sources, contributing to soil acidification, forest decline and eutrophication of waterways.”]  
  8. Galloway, J. N., et al., (2003). The nitrogen cascade. Bioscience, 53(4), 341-356. [“The same atom of Nr can cause multiple effects in the atmosphere, in terrestrial ecosystems, in freshwater and marine systems, and on human health. We call this sequence of effects the nitrogen cascade.” Abstract]
  9. U.S. EPA (2011) Reactive Nitrogen in the United States: An Analysis of Inputs, Flows, Consequences, and Management Options, A Report of the EPA Science Advisory Board, p. 4. [“Unlike other element-based pollution problems, the N cascade links the negative impacts, where one N-containing molecule can in sequence contribute to all the environmental issues mentioned above.”] [See also, Table ES-1 and pp. 41-42]  
  10. U.S. EPA (2011) Reactive Nitrogen in the United States, p. ES-6. [Of total NH3 emissions, “about 1 Tg N/yr (of a total of 3.1 Tg N) is advected out of the U.S. via the atmosphere.”] 

The two largest sources of newly created anthropogenic reactive nitrogen are chemical fertilizers applied to crops and the fixation of nitrogen from legume production (mostly from soybeans and alfalfa/hay).[1,2] Approximately two-thirds of that nitrogen is incorporated into plants and about a third of the nitrogen escapes into the air, water, and soil.[3]

The nitrogen taken up by the plants and thus retained in feed crops is ingested by farmed animals. The animals retain on average ~30% of the nitrogen, while ~70% of the nitrogen is excreted as manure.[4,5] Most of the nitrogen in manure is lost to the environment.[6] Of the total “leaked” nitrogen, about 15-20% escapes into the air as ammonia.[7,8]

About 85% of ammonia comes from agriculture, with animal ag responsible for the majority.[9]

Ammonia is a “precursor gas” that turns into PM2.5 – the most damaging component of air pollution to human health. Broadly estimated, agriculture is responsible for ~20-30% of the PM2.5 in the U.S., with most of that share due to ammonia emissions.[10,11]

 

  1. U.S. EPA (2011) Reactive Nitrogen in the United States: An Analysis of Inputs, Flows, Consequences, and Management Options, A Report of the EPA Science Advisory Board- 2011, p. ES-5. [65% from agricultural sources.] Reactive nitrogen includes any nitrogen compound on earth that is not N2, the nitrogen that makes up about 78% of the air. See, Nitrogen and Air Quality
  2. Sobota, D. J., et al., (2013). Reactive nitrogen inputs to US lands and waterways: how certain are we about sources and fluxes? Frontiers in Ecology and the Environment, 11(2), 82-90, Table 2. [69% from agricultural sources]
  3. Davidson, E. A., et al., (2011). Excess nitrogen in the US environment: trends, risks, and solutions. Issues in ecology, (15), p. 2. [“A large fraction of nitrogen fertilizer applied to cropland – often over half – is not used by the crops and is lost to air, water, and downstream and downwind habitats, polluting landscapes and waterscapes.”] [See, Nitrogen and Air Quality for further references]
  4. Davidson, E. A., et al., (2011), p. 10. [“Most livestock only utilize about 30% of the nitrogen in their feed; the rest is excreted in manure (feces and urine).”]
  5. Rotz, C. A. (2004). Management to reduce nitrogen losses in animal production. Journal of animal science, 82(suppl_13), E119-E137, p. E121. [Dairy 20 to 30%, feedlot beef 10%, pigs and poultry 30 to 40%] 
  6. See, Total Nutrient Volume in Manure
  7. Houlton, B. Z., et al., (2013). Intentional versus unintentional nitrogen use in the United States: trends, efficiency and implications. Biogeochemistry, 114, 11-23, Figure 3. [Estimate is 13% of total N lost to the environment via NH3. Of anthropogenic N creation this would be ~16%.]
  8. Sobota, D. J., et al., (2015). Cost of reactive nitrogen release from human activities to the environment in the United States. Environmental Research Letters, 10(2), 025006, p. 6 and Figure 4B. [At the national scale, N leakages per year = 4.8 Tg N surface freshwater, 4.2 groundwater, 3.0 ammonia, 1.9 coastal zones, 1.4 fossil fuel combustion. Calculation: 3.0 Tg N / 15.3 = 19.6%. Ammonia emissions have grown to ~5.5 million tons (~5 Tg N) per the EPA, so the 15-20% figure could be an underestimate.]
  9. U.S. EPA (2024) 2020 NEI Supporting Data and Summaries – Data Queries for Sector Summaries.[Query: National/Ammonia NH3/Livestock Waste (49.2%), fertilizer application (33.5%), agricultural field burning (2.7%) of total (5,482,484 tons). Of the 36.2% due to crop production, we estimate at least half is from feed crops.]
  10. Lelieveld, J., et al., (2015). The contribution of outdoor air pollution sources to premature mortality on a global scale. Nature, 525(7569), 367-371, Table 2. [Estimates 29% from agriculture in U.S. in 2010. There are varied estimates of this figure. See, Agricultural PM2.5 Pollution]
  11. Wyer, K. E., et al. (2022). Ammonia emissions from agriculture and their contribution to fine particulate matter: A review of implications for human health. Journal of Environmental Management, 323, 116285–116285, p. 1. [“NH3 emissions from agriculture are responsible for 30% of all PM2.5 in the US…”]            

There are many reasons:
 The number and complexity of animal ag gases and compounds defy analysis.[1,2]
 Animal ag emissions, especially ammonia, are in a constant state of chemical transition.[3]
 Current research is limited, especially in comparison to other major sources of air pollution.[4,5]
 Animal ag air pollution is fast moving and highly reactive, making attribution challenging.[6,7]
 The EPA has not focused on air pollution from animal ag because non-point sources are difficult to monitor, and our culture and traditions are averse to placing environmental constraints on farmers.[8,9]
 The impacts from fertilizers on feed crops (the nation’s largest crops) are not generally recognized as attributable to animal ag.

 

  1. Schiffman, S. S., et al., (2001). Quantification of odors and odorants from swine operations in North Carolina. Agricultural and Forest Meteorology, 108(3), 213-240. [“A total of 331 different VOCs and fixed gases were found at swine facilities in North Carolina.” Of all documented compounds, more than 150 were determined to be “irritants.”]
  2. U.S. EPA Office of Inspector General (2017) Eleven Years After Agreement, EPA Has Not Developed Reliable Emission Estimation Methods to Determine Whether Animal Feeding Operations Comply With Clean Air Act and Other Statutes, p. 3. [“AFOs can have many and varied sources of air emissions… Each of these emission sources can emit a variety of air pollutants, and emission rates can fluctuate depending on climate and geographical conditions… Further, characterizing AFO air emissions requires expertise in multiple scientific disciplines, including animal nutrition, AFO practices and atmospheric chemistry.”] 
  3. U.S. EPA (2011) Reactive Nitrogen in the United States: An Analysis of Inputs, Flows, Consequences, and Management Options, A Report of the EPA Science Advisory Board- 2011, p. 4. [“Unlike other element-based pollution problems, the N cascade links the negative impacts, where one N-containing molecule can in sequence contribute to all the environmental issues mentioned above.”]
  4. Congressional Research Service (2016) Air Quality Issues and Animal Agriculture: A Primer, RL32948, p. 1. [“Resolving those questions is hindered by a lack of adequate, accurate, scientifically credible data on air emissions from AFOs, data that are needed to gauge possible adverse impacts and subsequent implementation of control measures.”]        
  5. Lavaine, E., et al., (2020). Health, air pollution, and animal agriculture. Review of Agricultural, Food and Environmental Studies, 101, 517-528. [Few economic analyses exist regarding air pollution from agriculture compared to energy or transport (see, Figure 3).]
  6. Krupa, S. V. (2003). Effects of atmospheric ammonia (NH3) on terrestrial vegetation: a review. Environmental pollution, 124(2), 179-221, p. 181. [Ammonia life span of several hours to perhaps 1 to 4 days and a reach of ~.5 to 3 miles]
  7. Aneja, V. P., et al., (2008). Ammonia assessment from agriculture: US status and needs. Journal of Environmental Quality, 37(2), 515-520. [“ammonium aerosols might travel as far as 2500 km…”]
  8. Burns, A. M., et al., (2023). Data Gap: Air Quality Networks Miss Air Pollution from Concentrated Animal Feeding Operations. Environmental Science & Technology, 57(49), 20718–20725, p. 20722. https://doi.org/10.1021/acs.est.3c06947  [“Air pollution policy in the U.S. is primarily focused on large point sources, mobile emissions, and sources of toxic pollutants in highly populated areas.”]
  9. Congressional Research Service (2016), Summary. [“Agricultural operations have been treated differently from other businesses under numerous federal and state laws. Some environmental laws specifically exempt agriculture from regulatory provisions, and some are designed so that farms are not subject to most, if not all, of the regulatory impact.”]

Most assessments of ammonia-generated air pollution analyze the impacts on human health. There are far fewer assessments of ecosystems and the impacts on plant life and forests, even though the damage can be severe.[1-3]

Research pertaining to farmed animals is usually done in the context of efficient production, though some acknowledge the inherent suffering from constantly breathing highly polluted air.[4] Even though PM2.5 exposure has been extensively tested in lab settings on a variety of mammals, there is limited understanding of the direct impacts on wildlife.[5]

 

  1. Krupa, S. V. (2003). Effects of atmospheric ammonia (NH3) on terrestrial vegetation: a review. Environmental pollution, 124(2), 179-221, p. 212 [“Natural and semi-natural ecosystems, as well as forests must be expected to be severely at risk from the current amount of N deposition. Agricultural crops appear to be the only systems not negatively influenced at present, since high productivity and turnover prevent the accumulation of N.”]
  2. Behera, S. N., et al., (2013). Ammonia in the atmosphere: a review on emission sources, atmospheric chemistry and deposition on terrestrial bodies. Environmental Science and Pollution Research, 20, 8092-8131, pp. 8121–8124. 
  3. Guthrie, S., et al., (2018). The impact of ammonia emissions from agriculture on biodiversity. RAND Corporation and The Royal Society, Cambridge, UK, p. 7. [“Common, fast-growing species adapted to high nutrient availability thrive in a nitrogen-rich environment and out-compete species which are more sensitive, smaller or rarer.”]
  4. Bist, R. B., et al., (2023). Ammonia emissions, impacts, and mitigation strategies for poultry production: A critical review. Journal of Environmental Management, 328, 116919, p. 2. [“Chickens are very sensitive creatures that require precisely controlled indoor climate conditions inside poultry houses, and thus it is critical to reduce NH3 emissions or suppress indoor NH3 concentration.”]
  5. Shang, Y., & Sun, Q. (2018). Particulate air pollution: major research methods and applications in animal models. Environmental disease, 3(3), 57-62. [“Experimental animal models have been extensively used to study the underlying mechanism caused by environmental exposure to ambient PM.” at Abstract. “…mice, guinea pigs, and other rodents have been used in investigations related to pulmonary uptake and disposition of aerosolized particles.” at p. 58]     

The highest levels of ammonia emissions are inside factory farm sheds and on feedlots. Most affected are the animals who live daily with the fumes.[1]

Chickens, and especially egg-laying hens, endure particularly high ammonia levels with accompanying respiratory symptoms.[2-5]

Respiratory diseases in pigs are also common and a source of production losses.[6,7] Ammonia levels tend to be high in pig facilities due to the large accumulations of manure; high levels are a cause of pig respiratory diseases.[8,9] The most common diseases in feedlot cattle are respiratory.[10]

 

  1. For a helpful chart outlining factory farm ammonia levels and impacts, see, Ni, J. Q., et al., (2018). Ammonia and hydrogen sulfide in swine production. In Air Quality and Livestock Production, Banzhazi et al. (Eds.), London, UK, CRC Press, 29-47. [Table 1]
  2. Liu, S., et al., (2019). Modeling of dynamic ammonia concentrations in two commercial layer hen houses. Journal of Environmental Informatics, 33(1), 56-67. [“Ammonia (NH3) concentrations in confined layer hen houses are the highest among buildings of different animal species and are of great concern to indoor air quality and animal welfare.” at Abstract]
  3. David, B., et al., (2015). Air quality in alternative housing systems may have an impact on laying hen welfare. Part II—Ammonia. Animals, 5(3), 886-896, p. 888. [Cage-free housing facilities tend to have higher ammonia levels. Levels in winter tend to be higher, probably to save on heating costs by reducing ventilation.]
  4. Naseem, & King, A. J. (2018). Ammonia production in poultry houses can affect health of humans, birds, and the environment—techniques for its reduction during poultry production. Environmental Science and Pollution Research International, 25(16), 15269–15293. [See, Table 4 for a list of negative health impacts on poultry due to high ammonia levels.] 
  5. USDA APHIS (2014) Layers 2013, Part I: Reference of Health and Management Practices on Table-Egg Farms in the United States, 2013, p. 42. [On large farms, respiratory disease is the 2nd largest health issue.] 
  6. USDA APHIS (2016) Swine 2012, Part II: Reference of Swine Health and Health Management in the United States, 2012, p. 57 and 86. [PRRS (porcine reproductive and respiratory syndrome) is most common disease with influenza second]
  7. Opriessnig, T., et al., (2011). Polymicrobial respiratory disease in pigs. Animal Health Research Reviews, 12(2), 133-148.
  8. Ni, J. Q., et al., (2018), p. 1. [“Typical NH3 concentrations at swine facilities range from 0 to 40 ppm and are usually higher than at dairy and beef facilities, but lower than in poultry houses. The highest values are generally found in the finishing buildings.”]
  9. Samaneh Azarpajouh (October 2022) Impact on pigs of chronic exposure to ammonia. Pig Progress. https://www.pigprogress.net/health-nutrition/health/exposure-to-ammonia-on-pigs/
  10. USDA APHIS (2013) Feedlot 2011, Part IV: Health and Health Management on U.S. Feedlots with a Capacity of 1,000 or More Head, p. 18. [“Shipping fever, or bovine respiratory disease complex, is the most common morbidity and mortality event among feedlot cattle.”]      

Air Quality