Farming's Air Pollution: A Harmful Impact On Our Environment

Agriculture is a significant contributor to air pollution, with food production responsible for a quarter of the world's greenhouse gas emissions. Farms cause air pollution through various practices, including the application of fertilisers and insecticides, the rearing of livestock, the use of heavy-duty machinery, and the burning of crop stubble. These activities release methane, nitrous oxide, ammonia, hydrogen sulfide, and other pollutants into the atmosphere, impacting both the environment and human health. While agriculture is crucial for global food production, addressing agriculturally-caused air pollution is essential to protect the food system and the health and well-being of surrounding communities.

Animal waste and livestock operations

Animal waste from livestock is a leading source of air emissions on farms. A 2015 study in the journal Nature estimates that fine-particulate pollution from farms causes at least 3.3 million deaths each year globally. In the US, the livestock industry has long been exempt from reporting hazardous air emissions under federal law. However, a 2017 court decision would have required farmers and ranchers to report certain emissions from animal waste, such as ammonia and hydrogen sulfide, when released above certain thresholds.

Congress has since passed the FARM Act, giving the EPA more time to find a way for farmers to estimate their air emissions. The EPA has been trying to estimate emissions from livestock waste since the late 1990s, but claims it does not have sufficient data to develop accurate methods for determining whether livestock operations are subject to emissions permit requirements. Many factors influence air emissions from animal waste, including the number and types of animals, as well as their life stages.

In 2005, the pork, dairy, egg, and chicken industries funded a $15 million study to monitor air emissions at farms representing these sectors. The study measured ammonia, airborne particulate matter, volatile organic compounds, hydrogen sulfide, and carbon dioxide. It also recorded meteorological data, such as temperature and wind speed, and the number of animals, the type of animal housing, and the waste management practices at the site. The EPA was supposed to use the data to develop models for estimating hazardous air emissions from large-scale animal operations, but this has proven challenging.

Animal waste from all livestock contains odorous and potentially harmful hydrogen sulfide. Ammonia from animal waste can combine with pollutants from combustion to create aerosols, a collection of potentially harmful particulate matter suspended in the air that can damage human health. 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.

Use of pesticides and fertilisers

The use of pesticides and fertilisers in farming has a significant impact on air quality. Pesticides are substances designed to control or eliminate pests that can harm crops. They have played a crucial role in boosting agricultural productivity and ensuring food security. However, their use has unintended consequences, including air pollution. Pesticides can enter the atmosphere through aerial spraying, evaporation, volatilisation from crops and soils, wind erosion of contaminated soils, and emissions from manufacturing and disposal processes. They can also generate particulate matter (PM) when applied as sprays or dusts, which can be inhaled and cause respiratory issues.

Volatile Organic Compounds (VOCs) are chemicals found in many pesticides, which are released into the atmosphere during and after application. VOCs contribute to the formation of ground-level ozone, a major component of smog, which adversely affects respiratory health and the environment. Some pesticides also undergo chemical reactions in the atmosphere, forming secondary pollutants. These pollutants can be transported over long distances and affect areas far from the source of emission.

Nitrogen-rich fertilisers are a significant contributor to air pollution, releasing nitrogen oxides into the atmosphere. These gases remain in the atmosphere and affect public health, damaging the respiratory, circulatory, and immune systems. They have also been linked to pathologies in organs such as the liver and spleen. The industrialisation of agriculture, while helping to mitigate starvation, has been a source of endocrine and neurotoxic disorders, respiratory diseases, and certain cancers in countries like India.

Excess fertilisers also wash off fields each year, polluting watersheds. For example, an oxygenless "dead zone" spreads from the mouth of the Mississippi River each summer, fuelled by excess nitrogen from upstream. More careful fertiliser application and improved control of the environmental impact of the fertiliser industry are necessary to reduce this type of pollution.

Burning of fossil fuels and stubble

The burning of fossil fuels and stubble in farms is a significant contributor to air pollution. This activity releases various pollutants into the atmosphere, including greenhouse gases and airborne particles, which have detrimental effects on both human health and the environment.

Fossil fuels, such as oil, natural gas, and coal, are burned to generate energy for electricity production, transportation, and industrial processes. This burning process emits greenhouse gases, primarily carbon dioxide (CO2) and nitrous oxide (N2O), which intensify the greenhouse effect. The increased concentration of these gases in the atmosphere leads to higher average air temperatures, contributing to climate change and altering Earth's ecosystems. Additionally, the burning of fossil fuels releases nitrogen oxides, which contribute to the formation of smog and acid rain. These nitrogen oxides, along with other airborne particles like soot, also increase the reflectivity of the atmosphere, leading to a slight cooling effect.

Agricultural burning, or the practice of setting fire to fields to clear land, fertilize soil, and prepare for new crops, is a common method used by farmers worldwide. This process releases toxic smoke and microscopic pollutants, known as PM2.5, which can penetrate deep into the lungs and bloodstream. The health risks associated with exposure to PM2.5 include an increased risk of heart and lung disease, stroke, and certain cancers. In children, it can cause psychological and behavioural problems, while in older individuals, it is linked to Alzheimer's, Parkinson's disease, and dementia.

To address the issue of air pollution from burning fossil fuels, organizations can transition to renewable energy sources, improving their environmental impact and reducing greenhouse gas emissions. Additionally, conserving energy by using more efficient equipment and minimizing electricity usage can help lower air pollution from energy production.

Regarding stubble burning, alternative practices such as incorporating stubble back into fields or planting directly through the stubble are more cost-effective and environmentally friendly. Educating farmers about the negative consequences of burning agricultural waste and providing assistance in adopting alternative methods are crucial steps in reducing air pollution from stubble burning.

Fugitive emissions from machinery

Fugitive emissions, which are classified as Scope 1 direct greenhouse gas emissions, result from the direct release of GHG compounds into the atmosphere from various types of equipment and processes. Farms are associated with fugitive emissions from machinery, such as tractors and other farm vehicles, which contribute to air pollution.

Tractors and agricultural machinery are responsible for significant greenhouse gas emissions, which are influenced by both fuel consumption and exhaust gases directly emitted into the air. The use of fossil fuels and mineral resources in the construction and operation of this machinery further contributes to emissions. The variability of working conditions and the availability of machinery options can impact the environmental impact of these emissions.

Studies have evaluated the energy demand and greenhouse gas emissions of tractors with different power levels, ranging from 55 kW to 246 kW. The carbon footprint of tractors was found to vary between 11 and 30 t CO2e, while other agricultural machines produced between 27 and 176 t CO2e. The water footprint of tractors ranged from 21 to 55 m³, while other machines used between 35 and 391 m³.

To address the environmental concerns, researchers have explored solutions to reduce exhaust gas emissions from tractors and similar self-propelled machines. These include improving fuel efficiency, implementing technical solutions, and optimizing biofuel blends. The legislative limits and environmental sustainability considerations are driving the need to reduce pollutants from exhaust gases and improve air quality.

Lack of regulation and reporting

Agriculture is a significant contributor to air pollution in many regions worldwide. The lack of regulation and reporting in this sector exacerbates the problem, leading to adverse effects on the environment and public health.

One key issue is the inadequate measurement and modelling of agricultural emissions. Scientific assessments of agricultural air quality are an emerging field, presenting challenges to policy and regulatory authorities. The complex nature of the industry, encompassing a diverse range of activities, makes controlling emissions of gases and particulate matter from agriculture exceedingly difficult. This complexity demands rigorous scientific research to inform policy decisions effectively. However, the current policies often fall short, failing to address the intricate dynamics of the industry.

The absence of comprehensive regulations specifically targeting agricultural emissions allows for uncontrolled releases of pollutants. For instance, in the United States, agricultural emissions threaten the ability of states to comply with their legal obligations under the Clean Air Act. The livestock sector, in particular, is a major contributor to greenhouse gas emissions, nitrous oxide, methane, and ammonia, yet these emissions often go unregulated.

Furthermore, legislative changes, such as the "Fair Agricultural Reporting Method Act," have potentially hindered the reporting of hazardous substances released by agricultural operations. While certain environmental laws, like the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the Emergency Planning and Community Right-to-Know Act (EPCRA), mandate the reporting of hazardous substance releases within a 24-hour period, the effectiveness of these laws in the agricultural context is uncertain due to the aforementioned legislative changes.

The lack of regulation and reporting in agriculture contributes to the persistence of harmful practices, such as open burning of agricultural waste and the overuse of fertilizers. These practices result in the release of pollutants, including methane, nitrous oxide, and ammonia, which have detrimental effects on both the environment and human health.

Addressing the lack of regulation and reporting in the agricultural sector is crucial to mitigating air pollution and its associated impacts. This requires a multifaceted approach, including improved scientific research, effective policy interventions, and stringent enforcement of reporting requirements to ensure the protection of public health and the environment.

Frequently asked questions