Livestock's Air Pollution: The Unseen Emissions

Livestock produce air pollution in several ways, and the impact of this pollution on the environment and human health is significant. Animal farms produce food, but they also generate enormous amounts of waste that release around 400 different harmful gases into the atmosphere. These gases include nitrous oxide, methane, ammonia, particulate matter, endotoxins, and hydrogen sulfide. Livestock waste is the dominant contributor to ammonia emissions, which, when combined with other air pollutants, create tiny solid particles that can cause respiratory issues and even premature death when inhaled. The housing of livestock in confined feeding operations, known as concentrated animal feeding operations (CAFOs), makes their contribution to air pollution challenging to estimate. However, emissions from these operations are much higher than those for pasture-raised herds due to factors such as manure storage and silage. The overuse of antibiotics in livestock and unsanitary conditions on factory farms have also led to the airborne distribution of diseases like Swine Flu and Avian Flu.

Livestock waste

Ammonia emissions from livestock waste are particularly concerning. According to the EPA, animal waste contributes to 50-85% of ammonia emissions in the United States. The high levels of ammonia in the air can lead to respiratory problems and other health issues for people living near large-scale industrialized farms. The issue of ammonia pollution is especially prominent in states with a high production of eggs, such as Iowa, where emissions could rise unless the egg industry takes steps to mitigate releases.

The decomposition of factory farm waste further exacerbates air pollution. As waste decomposes, it releases airborne particulate matter and harmful gases. These particulates can include dry manure, feathers, feed, and animal dander, which contribute to the haze often observed near factory farms. The unsanitary conditions, poor animal feed, and overuse of antibiotics in these facilities can also result in the airborne spread of diseases such as Swine Flu and Avian Flu, affecting the health of nearby residents.

While certain practices, such as sustainable waste application in fields, can help mitigate emissions at farms with lower animal densities, these solutions are less feasible for large-scale industrial operations. The concentrated nature of these farms, known as Concentrated Animal Feeding Operations (CAFOs), makes it challenging to estimate their emissions accurately. Additionally, the varying types of animals, population sizes, and farm management policies further complicate the quantification of their environmental impact.

To address the air pollution caused by livestock waste, there is a growing need for accurate emission tracking and effective reduction strategies. However, the livestock industry has long been exempt from reporting hazardous air emissions under federal law. While a 2017 court decision briefly challenged this by requiring farmers to report certain emissions, Congress soon passed the Fair Agricultural Reporting Method (FARM) Act, exempting farmers and ranchers from disclosing air emissions to federal agencies once again. This lack of reporting and regulation makes it challenging to implement the necessary changes to reduce the air pollution caused by livestock waste.

Antibiotics and disease

Antibiotics are widely used in animal husbandry to promote growth and prevent diseases. However, the overuse of antibiotics in animal feed has caused serious environmental and health risks. The emergence of antibiotic resistance is one of the impacts of antibiotic pollution. The irrational use of antibiotics in animal feed has led to an increase in the antibiotic resistance rate of animal-derived bacteria and the emergence of "super-bacteria". The residual antibiotics in livestock and poultry excrement will pollute the surface water with the wastewater discharged from livestock farms or with rainwater.

Antibiotics are also contributing to air pollution. Livestock in the US produce 500 million tons of excrement every year, which emits around 400 different harmful gases into the atmosphere. These gases include nitrous oxide, ammonia, particulate matter, endotoxins, and hydrogen sulfide. When factory farm waste decomposes, it releases airborne particulate matter along with harmful gases. These particulates can include dry manure, feathers, bits of feed, and animal dander. They can travel through the air for miles and turn the sky hazy near the factory farm. The antibiotics that livestock are given to protect them while living in a high-stress, filthy environment are also potent airborne matter.

The overuse of antibiotics in livestock has also resulted in diseases that are not always easy to manage. For example, Swine Flu and Avian Flu can be distributed through the air, causing local residents to get sick. The best way to lower the amount of air pollution caused by animal agriculture is to go to the source. If we all take action to lower our consumption of meat and dairy, we can help lessen the demand for these products and slowly stunt the industry.

Ammonia emissions

Ammonia (NH3) is a colorless gas with a sharp, pungent odor. It is emitted from agricultural activities and is of particular concern because of its impact on health and the environment. Livestock farming is the main sub-sector responsible for ammonia emissions, with cattle being the primary source, followed by swine and poultry. In the United States, animal waste accounts for approximately 80% of ammonia emissions.

Ammonia is generated due to the presence of nitrogen in the feces and urine of pigs and cattle and the uric acid in poultry manure. It forms during the biological and chemical breakdown of manure protein, uric acid, and urea during manure storage and decomposition. The emission of ammonia gas is influenced by factors such as manure moisture content, temperature, nitrogen content, aeration conditions, and manure pH value. High-speed airflow above the manure increases ammonia emission, while a small surface area and low disturbance of the manure help reduce it.

Regulating and reducing ammonia emissions is crucial to mitigate these adverse effects. Opportunities to reduce emissions from livestock operations are already known and partially implemented. Some suggested methods to reduce ammonia emissions include adapting feed and using feed additives. Additionally, legislation such as the proposed Community Healthy Air Act in Maryland aims to address ammonia air pollution by mandating air monitoring near poultry houses to gather data and inform effective control measures.

Methane emissions

Livestock operations are a major source of air pollution, and among the various gases emitted by animal farms, methane is a significant contributor to greenhouse gas emissions. Methane is produced by ruminant livestock, including cattle, sheep, and goats, which have a unique digestive system that allows them to break down and digest food that is otherwise indigestible by non-ruminants like humans.

The specialized digestive system of ruminants involves a four-compartment stomach, with one compartment, known as the rumen, being responsible for storing partially digested food and allowing it to ferment. This fermentation process in the rumen produces methane, which is then expelled by the animal, primarily through belching. The methane produced by ruminant livestock contributes to the overall greenhouse gas emissions attributed to the livestock industry, estimated by the United Nations Food and Agriculture Organization (FAO) to be responsible for 14.5% of global emissions.

The amount of methane emitted by ruminant livestock can be influenced by their diet. It has been observed that cattle fed grain diets in feedlots produce less methane per pound of feed consumed compared to those grazing pastures. Improving the quality of feed by implementing optimal grazing management, growing high-quality forage crops, and supplementing diets with grain or energy-rich feeds can help reduce methane emissions. Additionally, selective breeding can be utilized to select for traits that result in lower methane production.

While modifying diets and breeding practices can help reduce methane emissions, it is important to note that the majority of the world's cattle do not have controlled diets, making it challenging to implement these strategies on a large scale. Furthermore, feeding grains to cattle raises concerns as it involves using human-consumable foods. Nevertheless, researchers at the CLEAR Center and other institutions are actively working on solutions to reduce methane production in cattle while considering animal health and performance.

Manure management

Poor manure management is common on farms worldwide. Farmers often lack awareness of the value of livestock manure as a fertilizer and fuel, instead opting to dispose of it in piles, slurries, or lagoons. This can lead to significant emissions of methane, a greenhouse gas, as well as environmental degradation, negative health impacts, and the loss of valuable nutrients that could be added to the soil.

The burning of pastureland and the use of dung as fuel for heating and cooking also emit black carbon, another pollutant. Methane is the main greenhouse gas emitted by liquid manure in storage. Livestock production is a source of greenhouse gases, which contribute to global warming.

The Climate & Clean Air Coalition promotes integrated manure and urine management practices that prevent harmful short-lived climate pollutant emissions while also providing added benefits for farmers through cost savings and additional income. The Coalition supports integrated practices that encompass all activities associated with the management of dung and urine: excretion, collection, housing, storage, anaerobic digestion, treatment, transport, application, and losses and discharge at any stage along the 'manure chain'.

The continuous improvement of livestock manure management practices will contribute to improved air quality, climate change mitigation, and sustainable agriculture. By implementing various mitigation strategies at different stages of the manure management chain, environmental impacts from livestock production can be significantly reduced. For example, removing manure 2–3 times per week or every day during the animal housing stage is an effective and simple way to reduce GHG and air pollutant emissions. Acidification during the manure storage and treatment stage can reduce ammonia and methane emissions by 33%–93% and 67%–87%, respectively.

Frequently asked questions