Agriculture's Air Pollution: Harmful Practices And Solutions

Agriculture is a major contributor to air pollution, with emissions from farms outweighing all other human sources of fine-particulate air pollution in much of the United States, Europe, Russia, and China. The primary sources of agricultural air pollution are ammonia, which enters the air as a gas from heavily fertilized fields and livestock waste, and emissions from farm equipment and vehicles. These emissions combine with combustion pollutants to form solid particles or aerosols, which can cause heart and pulmonary disease and are estimated to cause millions of deaths globally each year. In addition, agricultural operations involving animal rearing release methane, nitrous oxide, and other greenhouse gases, further contributing to air pollution and posing risks to human health and the environment.

Animal waste and heavy fertiliser use

Animal waste is a significant contributor to air pollution. Livestock produce 500 million tons of excrement every year, and when this decomposes, it releases harmful gases and airborne particulate matter. These include ammonia, nitrous oxide, particulate matter, endotoxins, and hydrogen sulfide. Livestock waste is responsible for 50 to 85% of ammonia emissions in the US, and around 80% of ammonia emissions come from animal waste. Ammonia emissions can cause dizziness, eye irritation, respiratory illness, and nausea, and releases of hydrogen sulfide can cause sore throats, seizures, comas, and even death.

In addition to the direct health risks, animal waste also contributes to acid rain. When waste breaks down, it forms ammonia gas, which then breeds bacteria that combine with other pollutants in the air to form nitric acid. This nitric acid builds up in the atmosphere and then falls back to Earth as acid rain, causing harm to soil, forests, and water ecosystems.

The concentration of gases produced by animal waste can be extremely dangerous to local communities. People living near animal farms often suffer from respiratory irritation, bronchitis, lung inflammation, dust toxic syndrome, asthma, and cardiac issues. The CDC has reported that people living near factory farms may experience mental health deterioration and increased sensitization to smells.

Factory farms, or Concentrated Animal Feeding Operations (CAFOs), are a significant source of animal waste pollution. These facilities keep thousands of animals together in confined spaces, and the waste is often left to fester in open-air lagoons. When these lagoons become full, farms may spray liquid manure into the air, creating mists of pollutants that are carried by the wind.

The heavy use of fertilisers is another major contributor to air pollution. Emissions from fertilisers combine with industrial emissions to form solid particles that are a major source of disease and death. Fertilisers are a significant source of ammonia, which enters the air from heavily fertilised fields and then combines with pollutants from combustion to form tiny solid particles or aerosols. These aerosols can penetrate deep into the lungs, causing heart and pulmonary disease. They are estimated to cause at least 3.3 million deaths globally each year.

The production of artificial fertilisers has increased drastically, from 20 million tons in 1950 to nearly 190 million tons today, with a significant proportion being nitrogen-based. The overuse of synthetic fertilisers has serious environmental and health impacts. Nitrogen released through synthetic fertilisers returns to the environment as nitrogen oxides, which have a much more harmful contribution to the greenhouse effect than carbon dioxide.

Excess nitrogen from fertilisers also remains in the soil, affecting its microbiology and altering the ratio of carbon and phosphorus. This can lead to soil eutrophication, acidification of agricultural land, and a loss of fertility. Additionally, nitrogen from fertilisers can contaminate water sources through runoff and leaching, affecting biodiversity and aquatic ecosystems.

To mitigate the impact of fertilisers on air pollution, it is crucial to use fertilisers in suitable proportions and compositions for the specific crop needs. Encouraging sustainable agricultural practices such as crop rotation and organic farming can help reduce fertiliser residues and their impact on the environment.

Livestock operations

Cattle, pigs, and chickens release methane, nitrous oxide, and ammonia into the air. Methane from cattle is particularly concerning as it is 28 times more potent than carbon dioxide in warming the atmosphere. Each year, a single cow can belch about 220 pounds of methane. While better breeding, genetics, and nutrition have increased the efficiency of livestock production, with fewer cattle needed to meet demand, the impact of the livestock industry on air pollution remains significant.

Livestock manure generates a large portion of the ammonia from agriculture, as well as a variety of other harmful pollutants. This is why meat, dairy, and other livestock production are among the top five sources of air pollution deaths, with a larger impact than truck exhaust. In addition to ammonia, other harmful gases such as hydrogen sulfide have been linked to neurological problems and increased levels of asthma in children living near livestock operations.

To improve air quality, farmers can implement certain practices. Using deep covered pits instead of anaerobic lagoons to store manure slurry can help prevent it from blowing away. Additionally, tweaking feed formulas, using minimal fertilizer, and employing more rotational crops can also contribute to better air quality.

Farm equipment

In addition to the direct emissions from farm equipment, the use of machinery in industrial crop production also contributes to air pollution. Soil plowing or tilling releases stored carbon into the atmosphere, adding to greenhouse gases. The extensive tilling of industrially raised crops can also increase particulate matter in the air, leading to dust and soil erosion.

Furthermore, the burning of fossil fuels to power machinery is not the only source of air pollution related to farm equipment. Fugitive pesticide emissions, which occur during aerial application, can harm farmworkers and impact nearby fields. The use of machinery in the large-scale application of animal waste can also expose workers and nearby communities to potent and harmful odors and air pollution.

While farm equipment is a contributor to air pollution, it is important to note that emissions from tractors and other farm vehicles are not the primary source of agricultural air pollution. According to studies, the greatest contributors to air pollution in agriculture stem from animal-raising operations and the use of fertilizers.

Soil, plants, animals, and fertilisers

Soil

Soil can be affected by air pollution, which in turn can have an impact on plant life. Increased air pollution contributes to smog and acid rain, which can damage soil and limit crop yields.

Plants

Air pollution can cause "yellowing" in plants, a term that refers to reduced growth, injury, or premature death. This is caused by nitrogen deficiency, demonstrating how short-lived air pollutants and ground-level ozone disrupt crop cycles and development. Plants near polluting industries are most likely to show this damage.

Animals

Industrialised animal agriculture is a major source of air pollutants. Concentrated animal feeding operations (CAFOs), where large numbers of animals are confined, are becoming more common as agriculture becomes more industrialised. Animal waste, feed, pesticides, antibiotics, and hormones are sources of hazardous emissions, including air pollutants and malodorous compounds.

Fertilisers

Heavy use of fertilisers is a major contributor to fine-particulate air pollution in much of the US, Europe, Russia, and China. Nitrogen-rich fertilisers and animal waste combine with industrial emissions to form solid particles, which are a source of disease and death. Agricultural air pollution often comes in the form of ammonia, which enters the air as a gas from fertilised fields and livestock waste.

Wildfires and agricultural burning

Wildfires emit particulate matter (PM) and gaseous compounds that can negatively impact human health and reduce visibility. The gaseous compounds include nitrogen oxides (NOx), carbon monoxide (CO), methane (CH4), and volatile organic compounds (VOCs).

PM2.5, or fine particulate matter, is a severe health hazard, especially when inhaled over long periods of time. Sources of PM2.5 include emissions from fossil fuel combustion, wildfires, and wind-blown desert dust.

The impact of wildfires on air pollution is influenced by several factors, including the type and amount of fuel consumed, meteorology, and burning conditions. Wildfires can also have long-term effects on air quality, as they can inject smoke high into the atmosphere, where it can remain for weeks or even months.

In addition to the direct impact on air quality, wildfires can also have indirect effects. For example, they can lead to economic burdens by impacting medical care, tourism, and property values. They can also cause ecological damage and affect visibility, which can have implications for transportation, aesthetics, and tourism.

The effects of wildfires on air pollution are particularly significant in certain regions, such as the Western US, where wildfires are common and have been increasing in frequency and intensity due to climate change.

To mitigate the impacts of wildfires on air pollution, it is important to implement fire management and evacuation programs in high-risk regions. Additionally, practices such as planting trees or shrubs to physically shelter crops from local sources of PM can also help reduce the effects of wildfires on air quality.

Frequently asked questions