Air Pollution: Nature's Fury And Our Future

Air pollution is a familiar environmental health hazard that affects people globally. It is caused by both natural and man-made processes. Natural sources of air pollution include wind-blown dust, wildfires, volcanoes, organic compounds from plants, sea salt, suspended soils, and dust. Wildfires, for instance, add carbon monoxide and particulate matter to the atmosphere. Methane, a significant greenhouse gas, is released into the atmosphere through waste disposal and the digestive processes of livestock. Natural sources of air pollution may not create ongoing air pollution problems, but they can be significant and cause harmful impacts when pollutants are transported over long distances.

Wildfires, volcanic eruptions, and dust storms

Natural air pollution refers to the contamination of indoor or outdoor air by various substances that can be harmful to human health and the environment, occurring independently of human activities. Examples of natural sources of air pollution include wildfires, volcanic eruptions, and dust storms.

Wildfires

Wildfires add carbon monoxide and particulate matter, which contains organic contaminants such as PAHs (polycyclic aromatic hydrocarbons), to the atmosphere. These contaminants can affect significant areas, depending on the scale of the wildfire and containment efforts.

Volcanic Eruptions

Volcanic eruptions release large amounts of gases and particles into the atmosphere, including sulphur dioxide, ash, and carbon dioxide. The extent of the volcanic ash cloud is influenced by factors such as particulate size, wind speed, direction, and eruption type. Smaller particulates, for example, enable the ash cloud to extend further and disperse over a broader area. Volcanic eruptions can also emit sulphuric acid, which falls as acid rain, negatively impacting both human health and ecosystems.

Dust Storms

Dust storms are characterized by strong winds carrying large amounts of dust particles, reducing visibility and degrading air quality. These dust particles, often originating from dry, loose soil or sediment, can be transported over large distances. Inhaling these fine particles can lead to respiratory issues, exacerbate existing conditions, and increase the risk of respiratory infections. Additionally, dust storms can carry allergens, pollutants, and potentially harmful microorganisms, further compromising air quality and impacting both short-term and long-term health.

Microbial decay and gases from livestock

Natural air pollution can be caused by a variety of processes, including microbial decay and gases from livestock. Microorganisms present in any environment play a significant role in the natural decaying process of living organisms and environmental contaminants. This activity results in the natural release of gases, particularly methane gas.

Livestock farms are a major source of microbial air pollution, with bacteria originating from farm animals and their excreta, mainly faeces. These bacteria can be transported by dust particles, which offer protection from biological decay. The physical decay of microorganisms depends on their size, while biological decay is influenced by factors such as humidity, temperature, radiation, and toxic gases. The viability of microorganisms and DNA decay are also impacted by meteorological conditions.

Studies have detected bacteria and antimicrobial resistance (AMR) genes associated with livestock farms, even at residential sites located 1200 meters away. The density of farms, particularly those with poultry and pigs, strongly correlates with the concentration of these microbes and genes. Epidemiological research has linked proximity to livestock farms with an increased risk of zoonotic infections and potential respiratory health effects, suggesting that microbial air pollution may play a role in these health outcomes.

Emission levels of microbial air pollution from farms vary over time, influenced by meteorological conditions and time-varying emissions. This variation offers an opportunity to investigate the acute effects of peak exposure levels. However, the lack of data on time-varying emissions presents challenges in modelling temporal variation accurately.

Livestock-related microbial air pollution has raised concerns about public health and environmental impact, with limited knowledge about airborne microbial levels in residential areas near farms. Further studies are needed to assess the risks associated with microbial exposures in these areas.

Natural sources of harmful gases

Natural air pollution refers to harmful gases and particles in the air that come from natural sources. These natural sources can include wind-blown dust, wildfires, and volcanoes. While natural sources of air pollution do not usually create ongoing air pollution problems, they can sometimes be significant and have severe impacts. For example, winds and air currents can carry pollutants over large areas, and wildfires can add carbon monoxide and particulate matter containing organic contaminants to the atmosphere.

One example of a natural source of harmful gases is microbial decaying processes. Microorganisms present in any environment play a role in the natural decaying processes of living organisms and environmental contaminants, releasing gases such as methane. Another example is radioactive decay processes, where natural decay of the Earth's crust can emit radon gas, which can accumulate in enclosed spaces.

Wildfires are another natural source of harmful gases and can have significant impacts on air quality. They release carbon monoxide and particulate matter, which can affect large areas and reduce visibility. Summertime wildfires can particularly impact areas downwind, causing haze and negative biological effects.

Volcanic eruptions are also natural sources of harmful gases, releasing toxic gases such as hydrogen sulfide. These eruptions can have severe impacts on the environment and human health, causing respiratory issues and other health problems.

Natural gas production and use can also result in the release of harmful gases into the atmosphere. While it is considered a relatively clean-burning energy source, leaks from wells, storage tanks, pipelines, and processing plants can occur, contributing to air pollution. Additionally, flaring, or burning off, natural gas at well sites produces carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen oxides, and other compounds, depending on the gas composition and burning efficiency.

Natural processes that cause air pollution

Air pollution is the release of various gases, finely divided solids, or finely dispersed liquid aerosols into the atmosphere at rates that exceed the natural capacity of the environment to dissipate and dilute or absorb them. Natural sources of air pollution include wind-blown dust, wildfires, and volcanoes.

Wildfires

Wildfires add carbon monoxide and particulate matter to the atmosphere. The particulate matter contains organic contaminants such as polycyclic aromatic hydrocarbons (PAHs). Wildfires can affect large areas, although they are usually restricted and contained. Control burning in forests and agricultural management can also emit gases and particulate matter.

Microbial decaying processes

Microorganisms present in any environment play a role in the natural decaying processes of living organisms and environmental contaminants. This activity results in the natural release of gases, especially methane gas.

Radioactive decay processes

For example, radon gas is emitted due to the natural decay processes of the Earth's crust, which can accumulate in enclosed spaces such as basements.

Increasing temperatures

Increasing temperatures contribute to an increase in the amount of contaminants volatilizing from polluted soil and water into the air.

Volcanoes

Volcanoes emit harmful gases and particles into the atmosphere, which can be transported by wind over large areas.

Natural sources of pollution vs. human-generated sources

Natural sources of pollution include wind-blown dust, wildfires, and volcanoes. Wildfires, for example, add carbon monoxide and particulate matter containing organic contaminants to the atmosphere. Natural sources of pollution can be significant, but they do not usually create ongoing pollution problems. For instance, wind can transport pollutants over large areas, but it does not create persistent pollution in a single location.

On the other hand, human-generated sources of pollution are often more concentrated and can lead to ongoing pollution issues. These sources are typically classified into four main types: mobile, stationary, area, and natural sources. Mobile sources, such as cars, trucks, planes, and trains, account for more than half of all air pollution in the United States, according to the Environmental Protection Agency. Stationary sources, like power plants, oil refineries, and factories, emit large amounts of pollution from a single location and are also known as point sources. Area sources, including agricultural areas, cities, and wood-burning fireplaces, contribute to pollution through the collective impact of multiple smaller sources. Finally, natural sources, such as those previously mentioned, can be influenced by human activities. For example, wildfires may be a natural source, but they can be exacerbated by human actions such as control burning in forest and agriculture management.

Another example of human-generated pollution is the release of pollutants during industrial processes, including the handling and storage of chemicals, waste incineration, and foundry activities. Agriculture also contributes to air pollution through the emission of ammonia gas and the use of pesticides, herbicides, and insecticides containing toxic volatile organic compounds. Additionally, waste incineration can release various toxic gases and particulate matter into the atmosphere. Military activities, smoking, and the use of household products containing organic solvents also contribute to air pollution.

Water pollution, a separate but related issue, is caused by harmful substances contaminating bodies of water, including chemicals and microorganisms. Oil pollution in seas and oceans is primarily attributed to land-based sources such as factories, farms, and cities, rather than tanker spills. Groundwater, an essential natural resource, is vulnerable to contamination from pesticides, fertilizers, and waste leached from landfills, rendering it unsafe for human consumption.

While natural sources of pollution exist, human-generated sources currently play a more significant role in creating and exacerbating pollution issues, particularly in the case of air pollution. The impact of human-generated pollution on the environment and public health has led to the implementation of regulations and the retirement of certain practices, such as coal-powered plants, to mitigate these effects.

Frequently asked questions