Concentrated animal feeding operations (CAFOs) and industrial crop production can affect air quality on farms and in surrounding communities by releasing ammonia, hydrogen sulfide, particulate matter, volatile organic compounds, pesticides and other contaminants into the air. CAFOs also contribute to greenhouse gas emissions, adding to the problem of climate change. Resulting air emissions and odors can harm the health of people working on a farm and in the surrounding communities, as well as the farm animals themselves.
Confining a large number of animals in close quarters concentrates the air emissions generated by farm animals. Cattle emit methane through belching and farting and from their waste (a mid-sized dairy farm with 200 cows produces approximately 24,000 pounds of manure every day 1), while poultry farms can release high levels of ammonia from the fermentation of feces in the litter. Animal waste from all livestock – a leading source of air emissions on factory farms – contains odorous and potentially harmful hydrogen sulfide.
The industrial model of farming crops in the US also contributes to air emissions. Soil plowing or tilling releases carbon into the atmosphere, as does burning fossil fuels to power farm machinery. Fugitive pesticide emissions can harm farm workers and impact nearby fields. Air emissions associated with large-scale animal waste application can subject workers and nearby communities to potent and potentially harmful odors and other types of air pollution.
Industrial farming operations reduce air quality in varying ways and also contribute to greenhouse gases. Each farm’s operations and management play some role in controlling emissions, and each farm (depending on its type) has different pollutants of concern. In 2012, livestock and poultry on the largest CAFOs produced 369 million tons of animal waste — that’s almost 13 times more waste than that of the 312 million people living in the US. 2 Untreated waste from these operations creates air pollution, which can cause odors, health problems and can diminish the quality of life of people who live nearby and lower property values.
While the US Environmental Protection Agency imposes no federal requirements on CAFO air pollution, some states have regulations on odor management or abatement; 3 some also regulate pollutants, like hydrogen sulfide and dust. 4 Local air quality can also be negatively impacted by burning diesel and other fuels. Crop-dusting, widespread pesticide application and spraying fields with animal waste can impact the local environment with concentrated doses of chemicals.
Two potent greenhouse gases, methane and nitrous oxide, are significant pollutants coming from industrial farming operations, along with ammonia, hydrogen sulfide and others. Here are some of the principle pollutants and their adverse effects.
Hydrogen sulfide is a manure gas that can be dangerous. At low concentrations, humans recognize its characteristic smell of “rotten eggs.” At higher concentrations, the gas can be deadly. On a spectrum in-between, concentrations of hydrogen sulfide can cause headaches, nausea, eye irritation and dizziness. Hydrogen sulfide is produced anaerobically by bacteria breaking down sulfur-containing material. The sulfur can originate from sources aside from manure, including animal feed, gypsum bedding and waste milk.
Hydrogen sulfide is heavier than air and hangs low to the ground if it is not blown away by the wind or otherwise dispersed. A top cause of air pollution occurs when manure lagoons are stirred to re-suspend solid waste, releasing high concentrations of the gas into the air. 5 Hydrogen sulfide may be detected on fields where manure is sprayed for fertilizer, and can be dispersed by the wind. 6
Ammonia is a colorless gas that is soluble in water. It is a nitrogen-containing compound that is produced in animal metabolism and excreted through animal waste. The EPA estimates that nearly three quarters of the country’s ammonia pollution comes from livestock facilities. Ammonia is an irritant and at high doses can be toxic. 7 Synthetic ammonia can be applied as a fertilizer.
Poultry housing is susceptible to elevated levels of ammonia that can negatively affect the birds’ health and development. Levels above 30 parts per million (ppm) are associated with these negative effects. The standards used by Animal Welfare Approved for their certification note that if any ammonia is detected in one of their certified facilities, elimination action must be taken, even at levels below 10 ppm. 8
The combination of ammonia from animal waste and fertilizer application with pollutants from combustion can create aerosols, which are a collection of potentially harmful particulate matter suspended in the air that can damage human health. 9 Studies have found that farms are a major source of fine-particulate precursors that form the aerosols that can then lead to heart or pulmonary disease. Particulate matter can be traced to dried manure, bedding materials, animal dander and poultry feathers. These particulates can cause or contribute to several respiratory diseases. 10
Air emissions from livestock operations make up 14.5 percent of global greenhouse gas (GHG) emissions. 11 In fact, the top three meat companies in the world have a carbon footprint the same size as France and nearly the size of a major multinational oil and gas corporation. 12 The most prevalent greenhouse gases, arising from animals’ digestive emissions and manure degradation, include methane and nitrous oxide.
Livestock farming emits several greenhouse gases that contribute to climate change, and may also be subject to the effects of climate change due to increased animal stress in dealing with rising temperatures.
Unlike more sustainable grazing systems, where well-managed pasture can act as nature’s sink in absorbing greenhouse gases from the air into the soil, industrial systems are faced with the enormous challenge of handling large quantities of animal waste and its GHG emissions into the air. How that waste is then captured, stored, treated and used impacts how much of the GHGs can be mitigated. 13 Given the vast quantities of waste produced in industrial animal systems, some have opted for expensive anaerobic digesters, which break down manure and burn GHG gases in anaerobic conditions (without oxygen), which have their own problems. 14 Other farms are either faced with large piles or lagoons of manure and/or dispersing the manure onto pasture and rangelands. Without efficient or effective composting, this pathogen laden waste becomes a significant hazard.
Industrial crop production also contributes to climate change. Nitrogen fertilizers are a source of nitrous oxide, a potent GHG. Machinery used to sow and harvest crops use fossil fuels to operate and emit carbon dioxide.
Farm workers are particularly vulnerable to air emissions on the farm due to direct and prolonged exposure. They also are tasked with being in the vicinity of concentrated forms of chemicals that can be dangerous or even deadly at high doses. Some of these effects include:
Researchers at the University of Nebraska Medical Center identified multiple respiratory diseases associated with working in animal confinement environments, including: rhinitis, sinusitis, mucus membrane inflammation syndrome, asthma, chronic bronchitis, chronic obstructive pulmonary disease, hypersensitivity pneumonitis and organic dust toxic syndrome. 15
These diseases can result from exposure to dust, other particulates and pathogens on the farm. They can also result from exposure to ammonia and hydrogen sulfide, and in the most serious instances, exposure to either chemical can cause death. Even at low concentrations workers may experience dizziness or nausea. 16
Farmers use pesticides on crops like corn and soybeans on over 90 percent of US fields, in order to control weeds, fungi, insects and other pests. 17 When pesticides are aerially applied, farm workers can be exposed to the chemicals, some of which have harmful effects on humans. Precautions should be put into place to minimize workers’ health issues arising from pesticide exposure.
Poor air quality can extend beyond the farm into surrounding communities. Due to limited regulation, factory farms can adversely affect quality of life for nearby homes, schools or towns by affecting health and the local economy.
Communities near factory farms typically do not have adequate regulations protecting them from air pollution. In 2009, the EPA released a rule exempting CAFOs from the emissions reporting requirements of CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act, also known as Superfund) and EPCRA (Emergency Planning and Community Right-to-Know Act, which sets requirements regarding releases of hazardous substances). 18 In 2017, a judge vacated that rule, 19 requiring many more livestock operations to report their emissions. However, the EPA still does not set maximum pollutant levels for CAFOs, so it is unclear what the reporting will accomplish. Aside from studies, the EPA also requires each state to produce a State Implementation Plan to identify sources of pollution and determine what actions are needed to comply with federal regulations. 20 Overall, farming practices lack many air quality regulations.
A ruling on April 26, 2018, found that a subsidiary of Smithfield, called Murphy Brown, would have to pay $50 million in damages to neighboring families who suffered from the odor, flies, buzzards and other issues caused by a neighboring hog operation. This was the first of 26 nuisance cases local residents have brought against the company. While the damages have since been reduced to $225,000 per person (due to a recently passed and interestingly-timed North Carolina “anti-nuisance” law that caps such penalties paid by agricultural entities), it remains an important precedent and sends a powerful message to these industry giants. Similar suits are being filed in other places including Northeast Iowa, where residents are suing the Iowa Department of Natural Resources.
Air pollution from industrial farming has the following implications for community health and well-being:
Some studies indicate that being in the proximity of factory farms may contribute to the instance or exacerbation of asthma cases.21 22 Airborne pollutants from factory farms are associated with lung irritation in general, and children and workers exposed to the emissions are more likely to experience asthma, wheezing and bronchitis. 23 Research has found that the closer children live to factory farms, the more likely they are to experience asthma symptoms. 24
Odors generated from animal waste application to fields or from waste lagoons; ventilation from indoor animal facilities; and odors from direct combustion of onsite materials has the potential to drift from farms onto nearby properties. Food and Water Watch observes that there are not only health effects, but that “factory farm odors diminish the quality of life for neighbors who can no longer hang their laundry out to dry, picnic in their yards, sit on their porches or even open their windows.” 25
Factory farms can negatively affect local economies. First, areas with new factory farms may have lower property values. One study in Iowa found that homes’ values suffered if they were located within three miles of a factory farm. 26 CAFOs can impact local infrastructure, provide little to no stimulus to the local economy and leave the environment in worse shape. 27 Factory farms often exist in close proximity to one another, in poor and minority communities. 28 Lower-income communities often have fewer options to confront the negative impact of factory farming, such as taking legal action or relocating for health reasons.
Dust and dirt are stirred up in industrial animal and crop operations. Animals in concentrated operations under dry conditions cause dried animal waste, dirt and dust to fly into the air. In feedlot conditions, cattle movement can trample vegetation and create dusty conditions that can lead to respiratory nuisances. Indoor-confined environments (e.g., poultry operations) can vent out particulate matter that can travel beyond the farm’s boundary and into the lungs of nearby residents. The extensive tilling of industrially raised crops can also cause particulates to enter the air, and can lead to soil erosion, making dust-ups even more common.
Sustainable farming practices can help mitigate air emissions and ensure that farm workers and animals are not exposed to harmful airborne pollutants. Sustainable agricultural practices, in particular, offer an alternative to industrial agriculture by working with natural ecosystems to make farming and ranching more sustainable and resilient. Agroecology uses a set of principles that can be suited to the unique physical and social contexts of a given location, particularly for certain growing conditions. To improve air quality, sustainable and organic practices keep animals on pasture where the manure does not concentrate and can break down aerobically, thus reducing emissions.
In raising animals, Animal Welfare Approved (AWA) standards are the gold standard for humane treatment. The techniques used to comply with their standards also help offset negative environmental conditions, including air pollution. For example, when raising chickens, the AWA standards require the monitoring of ammonia levels, because high levels are a problem for the welfare of the animals, workers and potentially for anyone nearby.
Practicing sustainable agriculture in the field can help maintain air quality by reducing the use of (and need for) chemicals that could pollute our air and water. Cover crops can help retain soil and moisture, avoid greenhouse gas emissions and in some instances help increase available nutrients for cash crops. No-till farming practices are another strategy to help the soil retain sequestered carbon in order to fight climate change while also preventing erosion (which can cause particulate matter (dust) entering the air). Combined, these practices are sometimes called carbon farming and together play a positive role in improving air quality and fighting climate change. 29 30