Agricultural Air Pollution: Harming The Environment And Our Health

Agriculture is a significant contributor to air pollution worldwide, with food production responsible for a quarter of the world's greenhouse gas emissions. The agricultural industry is crucial in producing enough food for the global population, but it is also one of the most damaging sectors on the planet. There are several ways in which agricultural activities cause air pollution, including the application of fertilisers and insecticides, the rearing of livestock, the use of heavy-duty machinery, and the burning of crop stubble. These practices result in poor air quality and contribute to climate change and global warming.

Livestock rearing

Cattle, in particular, are a major source of methane emissions, a greenhouse gas that is 28 times more potent than carbon dioxide in warming the atmosphere. The longer a cow lives, the more methane it emits, and cows in tropical regions produce less meat and milk, so they remain in the herd longer. Other livestock, such as sheep, are also significant emitters of methane.

Livestock waste, particularly manure, is a dominant source of ammonia emissions, which contribute to particulate matter in the air, leading to respiratory issues and premature deaths. Manure also produces hydrogen sulphide, a relatively under-reported greenhouse gas that contributes to global warming.

The practice of housing livestock in confined feeding operations, known as Concentrated Animal Feeding Operations (CAFOs), makes their contribution to air pollution challenging to estimate. However, it is known that emissions from these operations are much higher than those of pasture-raised herds due to the greater reliance on manure storage and silage.

To effectively reduce emissions from livestock rearing, accurate emission tracking and reduction strategies are necessary. This includes developing process-based models to track livestock emissions and investigating the meteorological impact of agricultural emissions.

Stubble burning

The health effects of air pollution from stubble burning are significant and far-reaching. Prolonged exposure to the pollutants released during stubble burning can cause or exacerbate respiratory diseases such as asthma and bronchitis, posing a severe threat to human health, particularly in regions with extensive burning. The pollutants can cause skin and eye irritation, as well as more serious neurological, cardiovascular, and respiratory issues. According to the Energy and Resources Institute, air pollution led to approximately 5 million deaths in South Asia in 2012, with stubble burning being a major contributor.

Despite being prohibited in most countries, stubble burning remains a popular practice in many places due to a lack of awareness about alternative management practices. Some sustainable alternatives to stubble burning include incorporating stubble into the soil, using it as fuel in power plants, or as raw material for the pulp and paper industries. It can also be used for compost and biochar production, or as a blend for cement and brick manufacturing. Implementing these alternative practices can help mitigate the environmental and health impacts of stubble burning and promote a greener agricultural future.

Use of heavy machinery

The use of heavy machinery in agriculture has made farmers' lives easier as manual tilling of the land is no longer necessary. However, the combustion of fossil fuels to power this machinery is a significant contributor to air pollution. Diesel-powered farm vehicles like tractors and combine harvesters generate a lot of carbon emissions.

The burning of fossil fuels releases carbon into the atmosphere, contributing to climate change and global warming. This is further exacerbated by the use of pesticides and fertilizers, which are also made with fossil fuels. The chemicals in these products can be blown off course or evaporate into the air, contaminating the local atmosphere and impacting the health of farmworkers and nearby communities.

Particulate matter, a term for solid or liquid particles found in the air, is another concern. Some particles are large or dark enough to be seen as soot or smoke, while others are so small they can only be detected with an electron microscope. These fine particles scatter and absorb light, creating a haze that limits visibility. While some sources of particulate matter may be local, such as industrial facilities or agricultural burning, it can also be widely dispersed, affecting visibility over large areas.

In addition to carbon emissions, the combustion of diesel fuel in heavy farm machinery also produces nitrogen oxides (NOx), which contribute to ground-level ozone pollution. According to the United Nations Environment Programme (UNEP), ground-level ozone pollution created by fuel burning and chemical use will reduce staple crop yields by 26% by 2030. This will have significant economic impacts, as reduced crop yields can affect food production and supply.

To mitigate the impact of heavy machinery on air pollution, farmers can consider transitioning to cleaner energy sources for their equipment, such as electric or renewable biofuels. Additionally, implementing measures to improve engine efficiency can help reduce NOx and particulate matter emissions, contributing to cleaner air and improved public health.

Fertilisers and insecticides

While agriculture is crucial for producing enough food for the global population, it is also one of the most environmentally damaging sectors. The application of fertilisers and insecticides is a significant contributor to air pollution in the agricultural sector.

Fertilisers play a crucial role in boosting crop yields by supplementing the vegetative development of crops with scarce nutrients. However, the overuse of synthetic fertilisers is having a serious environmental impact. Nitrogen released through synthetic fertilisers returns to the atmosphere as nitrogen oxides, which have a greenhouse effect 300 times more harmful than carbon dioxide. During the manufacturing process, soot and dust particles are emitted, along with polluting gases such as sulphur oxide, ammonia, nitric oxide, nitrogen dioxide, and volatile solvents. These emissions directly affect the environment and human health. To reduce the environmental impact of fertilisers, it is essential to use them in suitable proportions and under appropriate environmental conditions. Organic and mineral fertilisers are more environmentally friendly alternatives as they provide nutrients to plants without emitting synthetic derivatives that pollute the soil, water, and air.

Insecticides, along with pesticides, are used to minimise interference from insects, fungi, and weeds. However, the chemicals contained within these products can evaporate or be blown off course, contaminating the local atmosphere. Pesticides are considered volatile organic compounds (VOCs) and are major contributors to air pollution. They are released into the atmosphere through agricultural activities, as well as everyday products like paints and cleaning agents. The release of VOCs has been linked to between 340,000 and 900,000 premature deaths each year.

Ammonia emissions

Ammonia is released from livestock manure and synthetic fertilizer application. When ammonia is released into the atmosphere, it combines with other air pollutants, mainly nitrogen and sulfur oxide compounds, to form PM2.5. These fine particles can be carried long distances by the wind, impacting air quality in regions far from the source of pollution. PM2.5 can penetrate deep into the lungs, causing respiratory issues and long-term illnesses such as Chronic Obstructive Pulmonary Disease (COPD) and lung cancer. According to some studies, PM2.5 causes economic losses of billions of dollars annually to the global economy.

In the US alone, ammonia emissions from agriculture have been linked to reduced air quality and adverse health effects. These fumes from farms can cause respiratory health issues, including reduced lung function, throat and eye irritation, and increased coughing and phlegm expulsion. While the impact of atmospheric ammonia (NH3) on human health is not widely represented in scientific literature, it is believed to have direct effects on individuals working closely with livestock.

In Europe, ammonia emissions from agriculture continue to be a challenge. While emissions of most air pollutants in the European Union have been decreasing, ammonia emissions from the agricultural sector have been rising. This trend poses a threat to meeting EU air pollution limits. From 2016 to 2017, ammonia emissions increased by 0.4% across the EU, with an overall increase of about 2.5% from 2014 to 2017. This rise in emissions is attributed to the lack of emission reductions in the agricultural sector.

To address the issue of ammonia emissions from agriculture, regulations and sustainable practices are essential. Reducing ammonia emissions can lower ambient PM2.5 levels, thereby reducing their negative impact on human health and the environment.

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