Industrial farms pollute the air in many ways, emitting foul odors, dust and other small airborne particles, greenhouse gases, and numerous toxic chemicals. In the United States, these farms are among the leading producers of noxious substances such as nitrous oxidei and ammonia. Air pollution from industrial farms can cause health problems in agricultural workers, in neighboring communities and even for farm animals, and also results in significant environmental damage. Although there are a variety of techniques to reduce or minimize the impact of air pollution, many large farms still do little or nothing to prevent it.

Farm operations in the United States produce more than 400 different gases.iii In addition to gases, the other airborne particulates they create—such as dust and organic matter known as endotoxinsiv— can have damaging effects on air quality for both the farm and surrounding areas. These gases and particulates are generated during the handling and disposal of byproducts such as manure, the production and use of animal feeds, and also in the shipping and distribution of products.

Mountains of Manure
The USDA estimates that more than 335 million tons of manure are produced annually on farms in the United States.v This manure is generally stored for long periods of time in giant tanks or lagoons, where it decomposes and gives off hundreds of gases.vi Manure lagoons and tanks are often located directly next to animal confinement facilities, so harmful gases are continuously present in animal living quarters.vii They also pollute the outdoor air when stored gases are vented out of barns or manure slurry is sprayed onto fields as fertilizer.

Hydrogen sulfide, methane, ammonia, and carbon dioxide are the four main hazardous gases produced by decomposing manure,viii and they all cause a range of health and environmental problems. The EPA estimates that methane emissions from manure in the United States increased by 26% between 1990 and 2004, most of which it attributes to the trend towards larger and more concentrated dairy cow and swine facilities.ix The North Carolina hog industry alone produces about 300 tons of ammonia per day.x

Air Pollution and Feed
While manure is the largest contributor to farm-generated air pollution, a number of other factory farm components, such as conventional animal feed, also increase the production of some gases. The EPA estimated that in 2004, 20% of all man-made methane production came from the digestion processes of livestock—primarily cows.xi Factory farms use low-quality feed in large amounts to fatten animals cheaply, and this practice contributes to higher methane emissions.xii

Producing crops for animal feed also contributes to farm-generated air pollution. Soil management techniques (especially the use of fertilizers) are the leading contributor to nitrous oxide emissions, accounting for 68% of all nitrous oxide released into the air in 2004.xiii

Centralized Food Production and Fossil Fuel Use
The centralized nature of American food production contributes to air pollution, as food has to be stored for days and then transported over long distances before it reaches supermarket shelves. Conventionally-produced fruits and vegetables travel over a thousand miles on average between being harvested and sold.xiv Because of this, shipping agricultural products accounted for at least 1% of all freight trucking emissions in the United States in 2002, and that does not include the amount of freight (in the form of feed, building materials, etc.) shipped to farms in order to grow the food.xv

Health Effects of Farm-related Air Pollution
Health effects can vary widely by area, due to the various kinds and amounts of pollutants produced on farms and the different ways they’re vented. Below are some of the principle air pollutants released by factory livestock facilities, and the health problems that they may cause:

Effects on Workers
Since most of the air pollutants produced by farms are in much higher concentrations on the farms themselves than in neighboring areas, farm workers are at particular risk. Among workers on confined animal feeding operations, as many as 70% experience acute bronchitis and 25% chronic bronchitis.xxiii Additionally, a host of other respiratory ailments in workers have been linked to working in indoor swine production facilities for 2 hours a day over the course of six years, most likely as a result of organic dust inhalation.xxiv Some of the gases produced on farms also are fatal in high concentrations, and in the US there were 12 cases where workers were killed due to asphyxiation in manure pits between 1992 and 1997.xxv

Effects on Communities
Neighboring communities are also at risk for health problems from large farms. People living near hog farms, for example, often have increased respiratory problems.xxvi A number of studies have demonstrated that fatigue, depression, and mood disturbances occur in higher proportions in communities near such facilities.xxvii A study of one town in Utah found a four-fold increase in diarrhea-related hospitalizations and a three-fold increase in respiratory-related hospitalizations over a five-year period during which an industrial hog farm was constructed and became operational.xxviii The Minnesota Pollution Control Agency has documented that hydrogen sulfide concentrations in excess of World Health Organization maximum exposure standards can be found on neighboring properties of hog facilities in that state.xxix

Environmental Effects
Air pollution from farms directly affects the environment , chiefly through the production of gaseous nitrogen and some of the greenhouse gases responsible for global warming. About 80% of U.S. ammonia emissions came from livestock manure.xxx As a report from the National Academy of Sciences explains, atmospheric ammonia and nitric oxide—both produced on farms—contribute to what is known as the “nitrogen cascade,” in which each ammonia molecule “can, in sequence, impact atmospheric visibility, soil acidity, forest productivity, terrestrial ecosystem biodiversity, stream acidity, and coastal productivity.”xxxi Particulate matter emissions contribute to haze.xxxii Through the production of greenhouse gases—primarily methane and nitrous oxide—the agricultural industry was directly responsible for 6 percent of the United States’ impact on global warming in 2004, according to the EPA.xxxiii

Remedies and Regulations
There are already a number of proven techniques that can reduce the impact and total emissions of air pollutants from farms, including better storage of manure, air-breaks positioned near farms, and increased attention to the nutritional needs of specific livestock.xxxiv Additionally, some measures as simple as allowing cows to graze on pasture (which has also been shown to be healthier than grain-feeding for both cows and humans) have the potential to reduce greenhouse gas emissions.xxxv Raising animals on pasture also reduces the need for cultivation and transportation of feed, as well as storage and spreading of manure, all of which require the use of fossil fuels and emit significant amounts of carbon dioxide and other pollutants.

However, since most methods that reduce air pollution from farms would increase maintenance costs without increasing production, factory farms don’t see it as in their interest to implement them. In addition to the financial disincentive against regulating emissions from farms, there is little regulatory incentive to promote their regulation. While most farm emissions are legally regulated under the Clean Air Act, most enforcement attention has been focused on factories and cars—both of which are far easier to measure in terms of their contribution to air pollution.xxxvi The federal government has also done relatively little to handle the problem, leaving enforcement of farm-related air pollution to individual state governments, xxxvii and generally leaving research on the topic to academics.xxxviii
There is also concern that better environmental regulation will not stop much of the air pollution from farms. Instead, tighter regulations could cause many of the largest corporate farmers to move to overseas locations. Already, some of the biggest American agricultural companies (including Perdue and Smithfield) are now producing and processing foods in Canada, Mexico, Europe, China and Brazil to reduce costs and avoid being hindered by existing environmental regulations.xil Because of this, the best way to get industrial farms to change their ways is not through tightening regulations, but with consumers’ food dollars.

What You Can Do

The problems associated with most farm emissions are primarily local and regional, and the most efficient way to reduce air pollution from farms is to reduce the size and increase the number of farms. In other words, many small farms scattered throughout the country will have less of an impact on air quality than conventional factory farms do. Sustainable livestock farms depend less on cheap feed and fuel-guzzling machinery, because natural pasture systems rely on the animal’s own energy to harvest feed and spread manure. Because of this, sustainable farming offers a viable opportunity to reduce farm-related air pollution.

As consumers, we can use our economic power to support farms that supply sustainably-produced meat, eggs and dairy products. By giving our dollars to farmers who work to minimize their impact on the environment and protect human health, we can vote with our wallets and help change the face of American agriculture, so we can all breathe easier.

Did You Know?

For More Information