Air Pollution: Agricultural Impact And Influence

Agriculture and air pollution have a complex, bidirectional relationship. Agriculture is a significant contributor to air pollution, with food production responsible for a quarter of global greenhouse gas emissions. Animal-raising operations, in particular, release methane, nitrous oxide, and ammonia into the atmosphere. However, air pollution also negatively impacts agriculture, reducing crop yields and causing economic losses. The relationship between agriculture and air pollution is an important area of study, as it has implications for environmental science, public health, and policy development. Understanding this relationship is crucial for creating sustainable agricultural practices and mitigating climate change.

Agriculture's contribution to air pollution

Agriculture is a significant contributor to air pollution worldwide. Food production is responsible for a quarter of the world's greenhouse gas emissions. The agricultural sector impacts air quality through emissions from tractors and farm vehicles, and the greatest agricultural contributors to air pollution are animal-raising operations. Cattle, pig, and chicken operations release methane, nitrous oxide, ammonia, and other harmful gases into the air. These gases can have detrimental effects on the environment and pose risks to human health.

Ammonia emissions from livestock manure and chemicals comprise 95% of ammonia emissions, which, in turn, account for 58% of the particulate matter air pollution in European cities. Particulate pollution can create a haze that limits visibility and has been linked to adverse health effects. In North India, agricultural burning of crop residue is a major source of particulate pollution, with levels regularly exceeding the recommended WHO limit by more than 1000%.

Agricultural operations also contribute to air pollution through the use of nitrogen-rich fertilizers, which can combine with industrial emissions to form solid particles that are harmful to human health. The production of artificial fertilizers has increased significantly, and their use is expected to double in the coming decades. While fertilizer use contributes to air pollution, it is important to note that industrial sulfates in fertilizers have been credited with reflecting solar radiation, thereby slightly mitigating global warming caused by other fossil fuel emissions.

In addition to air pollution, agriculture is also affected by poor air quality. Particulate pollution interferes with crops' ability to photosynthesize sunlight, reducing yields. Ozone, a byproduct of air pollution, is toxic to crops. Climate change caused by air pollution can also lead to rising temperatures, damaging crop production. Therefore, addressing air pollution and adopting climate-friendly policies can have dual benefits for both the environment and agriculture.

To mitigate the impact of agriculture on air pollution, various strategies can be employed, such as adopting no-till practices, improving fertilizer application techniques, implementing regulatory frameworks, and utilizing sustainable agricultural practices. By reducing dust generation and particulate pollution, no-till techniques have been shown to improve air quality and reduce mortality rates in downwind communities. Additionally, addressing industrial emissions and adopting cleaner technologies in agriculture can help decrease air pollution and improve overall environmental sustainability.

Air pollution's impact on agriculture

Agriculture and air pollution have a bidirectional relationship, with agriculture being a significant contributor to air pollution and air pollution negatively impacting agricultural output.

Impact of Air Pollution on Agriculture

Air pollution has been linked to climate change, with short-lived air pollutants being responsible for 30-40% of atmospheric warming happening today. 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. The UN Food and Agriculture Organization also predicts that crop yields of staples like rice, maize, and wheat will decrease by up to 10% per degree Celsius of global warming. Extreme weather and heat will cut staple crop yields across the Mediterranean region by up to 25% in the coming decades.

Particulate pollution directly interferes with crops' ability to photosynthesize sunlight, reducing yields, while other pollutants like ozone are toxic to crops. High amounts of ozone in the atmosphere can inhibit plant growth.

Addressing the Issue

The negative impacts of air pollution on agriculture can be mitigated through the adoption of climate-friendly policies and sustainable agricultural practices. For example, no-till techniques, which reduce soil disturbance and dust generation, can lead to substantial reductions in air pollution and corresponding reductions in mortality in downwind communities. Additionally, tackling agriculturally-caused air pollution is imperative for the food system. This includes reducing emissions from animal-raising operations, as cattle, pig, and chicken operations release methane, nitrous oxide, and ammonia into the air.

Livestock and ammonia emissions

Livestock and poultry farming are the largest contributors to ammonia emissions, according to the USEPA national emission inventory. Among the livestock and poultry industry sectors, dairy and beef cattle production contribute about 54% of total ammonia emissions, poultry production contributes 33%, and swine 12%. Ammonia emissions are caused by excess protein—which contains nitrogen—in livestock feed. The nitrogen that is not metabolized by the animal is excreted in urine as urea, which a bacterial enzyme called urease then turns into ammonia. Cows excrete up to 90% of the nitrogen they eat, while growing pigs excrete about 70%. However, balanced diets can cut nitrogen excretion by as much as 40%.

Ammonia emissions from livestock also vary with factors such as animal diets, housing, and manure management. Dairy cows' ammonia emissions vary primarily by flooring, feed, and season. Starch in livestock diets, for example, corn silage, leads to lower emissions from lactating dairy cows. This is because starch is broken down into a compound (propionate) that does not produce methane, unlike plant fibers, which are broken down into acetate, a methane-producing compound.

Ammonia emissions from livestock are a significant concern as they impact human health and the environment. Ammonia (NH3) is a nitrogen compound that contributes to the greenhouse gas nitrous oxide and fine airborne particles that threaten human health. It is a colorless gas with a sharp, pungent odor that can be smelled at about 5 to 18 ppm (parts per million). At low concentrations of 5–100 ppm, ammonia is a strong irritant that inflames the eyes and lungs. Immediate irritation of the eyes, nose, and throat occurs at 400–700 ppm, and severe eye irritation, coughing, and frothing at the mouth, which could be fatal, occur at 2000–3000 ppm.

Ammonia emissions also harm the environment by acidifying soil and adding nitrogen to lakes, boosting plant growth at the expense of animal life. In the U.S., agriculture accounts for more than 80% of ammonia emissions, which have overtaken motor vehicles and industry as the dominant source of nitrogen pollution. According to another source, agriculture contributes to more than 81% of all global NH3 emissions. Therefore, reducing ammonia emissions from agriculture is crucial to improving air quality and mitigating the health and economic impacts of air pollution.

The role of agricultural burning

The relationship between agriculture and air pollution is a complex one. While agriculture is a significant contributor to air pollution, it is also affected by it. Air pollution can negatively impact crop yields and cause economic losses. Therefore, addressing air pollution is crucial not only for human health but also for ensuring food security.

Agricultural burning, specifically the burning of crop residue, is a major contributor to air pollution. This practice is prevalent in many parts of the world, including North India, where it has been identified as a significant source of particulate pollution. Farmers burn crop residue to clear their fields and prepare for the next planting season. While this method allows for cheap and fast disposal of crop residue, it releases harmful pollutants into the atmosphere.

The impact of agricultural burning on air quality and public health has been well-documented. In India, for example, crop residue burning has been linked to an estimated 44,000–98,000 premature deaths annually due to particulate matter exposure. The situation is particularly severe in North India, where levels of particulate pollution regularly exceed the World Health Organization (WHO) limit by more than 1,000%.

To address the issue of agricultural burning, various interventions have been proposed and implemented. These include government bans, mechanized approaches, and alternative methods for residue disposal. However, despite these efforts, agricultural burning remains widespread. This persistence can be attributed to factors such as the convenience and cost-effectiveness of burning compared to alternative methods.

Additionally, the implementation of certain policies has inadvertently contributed to an increase in agricultural burning. For instance, the Mahatma Gandhi National Rural Employment Guarantee Act (MNREGA) in India led to a 21% increase in the use of fires to clear residue. This increase was driven by farmers' shift towards mechanized harvesting, which resulted in more residue on the fields.

To effectively mitigate the impact of agricultural burning on air pollution, it is essential to develop targeted strategies that consider the specific contexts and challenges of different regions. Small interventions, such as altering the time of day when burning occurs, can also provide broad public health benefits. By addressing the issue of agricultural burning, significant improvements in air quality and public health can be achieved, contributing to the overall goal of cleaner air for all.

Policy considerations and interventions

The complex relationship between agriculture and air pollution has significant implications for policymakers. On the one hand, agricultural practices, such as the use of fertilizers, pesticides, and livestock operations, contribute to air pollution through emissions of ammonia, methane, nitrous oxide, and particulate matter. On the other hand, air pollution negatively affects agricultural productivity and crop yields, creating a bidirectional relationship that needs to be carefully addressed in policy interventions. Here are some considerations and potential strategies for policymakers:

• Regulating Agricultural Emissions: Policymakers should focus on developing and enforcing regulations to reduce emissions from agricultural practices. This includes setting standards and limits on the use of fertilizers and pesticides, promoting sustainable manure management practices, and supporting the adoption of cleaner technologies in farming, such as electric farm equipment.
• Incentivizing Sustainable Agricultural Practices: Governments can provide incentives for farmers to adopt sustainable and environmentally friendly practices. This could include subsidies or grants for implementing conservation tillage, such as no-till farming, which reduces soil disturbance and particulate pollution. Other sustainable practices like integrated pest management, crop rotation, and organic farming methods should also be encouraged to reduce chemical inputs and their associated emissions.
• Improving Measurement and Monitoring: There is a need for improved measurement, monitoring, and scientific understanding of agricultural emissions. This includes investing in research and technology to accurately measure emissions from various agricultural sources, including livestock operations, fertilizer use, and agricultural burning. This data will inform effective policy design and enable better assessment of the impact of interventions.
• Collaborative Policy Development: Policy interventions should be informed by collaboration between scientists, farmers, and regulatory authorities. Workshops, such as the international workshop on agricultural air quality mentioned in the sources, can help synthesize scientific knowledge, address knowledge gaps, and involve stakeholders in the policy-making process. By involving farmers, policymakers can also ensure that interventions are practical and take into account the economic realities of agricultural operations.
• Addressing Deforestation and Land Degradation: Policies should address the role of the livestock sector in deforestation and land degradation, which have indirect but significant impacts on air quality and climate change. Strategies could include promoting sustainable land-use practices, reforestation initiatives, and incentivizing alternative protein sources or more efficient livestock management practices that reduce the environmental footprint of animal agriculture.
• Regional and International Cooperation: Air pollution and its impacts do not respect national borders. Regional and international cooperation is essential to effectively address agricultural air pollution. Sharing best practices, coordinating policies, and addressing transboundary pollution issues through agreements and treaties are vital aspects of a comprehensive policy response.

In conclusion, addressing the complex relationship between agriculture and air pollution requires a multifaceted policy approach that considers both the contributions of agricultural practices to air pollution and the impacts of air pollution on agricultural productivity. By implementing a combination of regulatory measures, incentives for sustainable practices, improved scientific understanding, and collaboration across sectors and regions, policymakers can make significant strides in mitigating the negative impacts of this bidirectional relationship.

Frequently asked questions