Air Pollution: What's The Definition?

Air pollution is a significant environmental health hazard, defined as the presence of harmful substances in the air that modify its natural composition. These substances, known as pollutants, can be gases, fine particles, or chemicals, and they are released into the atmosphere through a combination of human-made and natural sources. The burning of fossil fuels, vehicle emissions, industrial processes, and natural occurrences like wildfires and volcanic eruptions are all significant contributors to air pollution. It poses a severe threat to human health and the planet, causing approximately 7-8 million deaths annually and leading to economic losses of over $8 trillion per year.

Particulate matter (PM)

PM is classified according to size, rather than chemical composition. The two major types of PM are:

• PM10: Coarse inhalable particles with a diameter of 10 micrometres or less. These particles can be inhaled into the lungs and can induce adverse health effects, particularly the worsening of respiratory diseases.
• PM2.5: Fine inhalable particles with a diameter of 2.5 micrometres or less. These particles pose the greatest risk to health and are the main cause of reduced visibility (haze) in many places. They can cause tissue damage by entering organs directly or indirectly through systemic inflammation. Long-term exposure to PM2.5 has been linked to premature death, particularly in people with chronic heart or lung diseases, and reduced lung function growth in children.

PM is emitted from a variety of sources, including cars, trucks, buses, factories, construction sites, burning wood, and more. Certain types of particles, such as asbestos fibres, are known carcinogens, while many others are formed of complex organic chemicals that are suspected of being carcinogenic.

Health studies have shown a significant association between exposure to fine particles and premature death. Other effects include the aggravation of respiratory and cardiovascular disease, lung disease, decreased lung function, asthma attacks, and certain cardiovascular problems such as heart attacks and irregular heartbeats.

Natural sources of air pollution

Volcanic eruptions can spew massive amounts of sulphur dioxide into the atmosphere. Volcanoes used to be the main source of atmospheric sulphur dioxide. Large amounts of harmful gases and smoke are released during volcanic eruptions, which can increase background pollution levels for years, even in areas far away from the original source.

Wildfires are another natural source of air pollution. They release harmful pollutants, including particulate matter, carbon monoxide, and ozone, which can have serious health impacts. Particulate matter, specifically PM 2.5, can be inhaled deeply into the lung tissue and contribute to severe health problems. It accounts for most health effects due to air pollution in the US.

Animals like cows and sheep release large amounts of methane through belching and flatulence. Methane is a colourless gas produced in their stomachs when bacteria break down the food they eat. Livestock is the biggest source of methane worldwide. Methane is the second most important greenhouse gas, which can cause climate change.

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

Human sources of air pollution

Air pollution is defined as the presence of substances in the air that are harmful to humans, other living beings, or the environment. These substances are called pollutants, and they can be solid particles, liquid droplets, or gases.

Human activities are a major contributor to air pollution, with the burning of fossil fuels being the most significant source. This includes the use of fossil fuels for industry, construction, transportation, and heating. For example, cars, trucks, factories, power plants, and airplanes that burn gasoline or diesel contribute significantly to air pollution. The combustion of fossil fuels releases harmful gases such as carbon dioxide, nitrogen oxides, and sulfur dioxide, as well as particulate matter (soot).

In addition to the burning of fossil fuels, there are other human activities that contribute to air pollution:

• Industrial processes: Certain industries, such as oil and gas development, release pollutants into the air through their production processes. This includes emissions of volatile organic compounds (VOCs) and the release of methane during drilling.
• Waste management: Improper disposal and treatment of waste can release harmful chemicals and gases into the air.
• Agriculture: Agricultural practices, such as the use of pesticides and fertilizers, can contribute to air pollution. Ammonia, for example, is emitted mainly by agricultural waste.
• Nuclear activities: The use of nuclear weapons, toxic gases, and rocketry can release radioactive materials and harmful chemicals into the atmosphere.
• Residential activities: The use of biomass (such as wood) for cooking and heating can release pollutants, including carbon monoxide. Other residential sources include tobacco smoke, paint fumes, hair spray, and aerosol sprays.

Air pollution laws

Air pollution is defined as the presence of substances in the atmosphere that are harmful to humans, other living beings, or the environment. These substances are released at rates that exceed the environment's capacity to dilute or absorb them. They may reach concentrations that cause undesirable health, economic, or aesthetic effects.

The Clean Air Act (CAA)

The Clean Air Act is a comprehensive federal law enacted in the United States in 1963 or 1970 (sources vary). It authorises the US Environmental Protection Agency (EPA) to regulate air emissions from stationary and mobile sources to protect public health and the environment. The EPA sets limits on certain air pollutants and emissions, including carbon monoxide, nitrogen oxides, particulate matter, and sulfur dioxide. The CAA also mandates controls on air pollution from motor vehicles and non-road engines by regulating fuel composition and emission-control components.

National Ambient Air Quality Standards (NAAQS)

The NAAQS are established by the EPA under the Clean Air Act. These standards set acceptable concentrations of six major air pollutants, known as ""criteria" pollutants, which include sulfur dioxide, nitrogen dioxide, and carbon monoxide. The NAAQS aim to protect public health and prevent significant deterioration in air quality.

Maximum Achievable Control Technology (MACT) Standards

MACT standards are technology-based emission standards established by the EPA for "major sources" of hazardous air pollutants under Section 112 of the Clean Air Act. These standards require the maximum degree of reduction in emissions from stationary sources emitting large quantities of hazardous pollutants.

State Implementation Plans (SIPs)

The Clean Air Act directs states to develop SIPs, which consist of emission reduction strategies. The goal of these plans is to achieve compliance with the NAAQS by the legislated date. States may have stronger air pollution laws than the federal standards, but they cannot have weaker pollution limits.

International Efforts

Internationally, efforts such as the Montreal Protocol have successfully reduced the release of harmful ozone-depleting chemicals. However, other initiatives, such as global action on climate change, have been less successful. The World Bank estimates that the welfare and productivity losses caused by air pollution cost the global economy over $8 trillion per year.

Health effects of air pollution

Air pollution is defined as the presence of substances in the air that are harmful to humans, other living beings, or the environment. It refers to the release of pollutants—gases, small particles, or chemicals—into the air. These pollutants are detrimental to human health and the planet as a whole.

Air pollution is a significant risk factor for several diseases and health problems, including:

• Cardiovascular Issues: Exposure to air pollution has been linked to an increased risk of heart attacks, irregular heartbeat (arrhythmia), heart failure, and strokes. The tiny particles in the pollution can enter the bloodstream and cause inflammation in blood vessels. Over time, this can contribute to the development of heart disease. Even short-term exposure to polluted air can have negative effects on heart health.
• Respiratory Problems: Air pollution is a major cause of respiratory issues, including chronic obstructive pulmonary disease (COPD), asthma, bronchitis, and respiratory infections. Ozone, a key component of smog, is a powerful lung irritant that can cause chest pain, coughing, and throat irritation. Long-term exposure to ozone can lead to decreased lung function and chronic respiratory conditions. Nitrogen dioxide (NO2) and sulfur dioxide (SO2) are also respiratory irritants that can worsen asthma and increase susceptibility to respiratory infections.
• Cancer: Air pollution has been associated with an increased risk of lung cancer, as well as other types of cancer. The presence of toxic chemicals in the blood, such as those released from burning fossil fuels, can contribute to the development of cancerous cells.
• Neurological Impact: Studies have indicated a link between air pollution and adverse effects on brain development and mental health. Research has shown that air pollution can impact children's brain and behavioural development. Additionally, exposure to polluted air has been associated with an increased risk of bipolar disorder and major depression in adults.
• Prenatal and Childhood Health: Pregnant women exposed to air pollution face potential risks, including increased levels of toxic chemicals in the blood, which can weaken the placenta and lead to preterm or low birth weight babies. Traffic-related air pollution has also been linked to slowed brain development in children. Children, in general, are more susceptible to the harmful effects of air pollution due to their developing bodies and proximity to sources of pollution, such as living in lower-income areas or being near busy roads.
• Other Health Issues: Air pollution has been associated with various other health problems, including chronic bronchitis, pneumonia, and autoimmune diseases. It can also aggravate existing allergies and trigger asthma attacks. Additionally, indoor air pollution, such as from freshly painted walls or certain cleaning products, can cause eye and nose irritation, headaches, and dizziness.

It is important to note that certain individuals may be more susceptible to the health impacts of air pollution, including pregnant women, children, older adults, and people with existing chronic conditions, especially heart and lung diseases. Additionally, low-income communities and minority groups often face higher risks due to proximity to pollution sources and limited access to healthcare.

Frequently asked questions