Air Pollution: Is The Air We Breathe Safe?

Air pollution is a pressing global issue, with 99% of the world's population breathing air that exceeds the World Health Organization's (WHO) guideline limits. It is deemed the greatest environmental health risk, causing an estimated 7 million premature deaths annually. The primary sources of air pollution are both natural and man-made, with the latter being the leading contributor in cities. Man-made sources include combustion from transportation, industrial businesses, biomass burning, and agriculture. Natural sources include volcanic activity, wildfires, dust, and sandstorms. The Air Quality Index (AQI) is a tool used to communicate outdoor air quality and health, with higher AQI values indicating greater levels of air pollution and health risks. Various websites and tools provide real-time air quality data and maps, allowing people to monitor the air pollution levels in their local areas and across the globe.

What is the Air Quality Index (AQI) and how is it measured?

The Air Quality Index (AQI) is a public system that warns people about dangerous levels of air pollution. It is an indicator developed by government agencies to communicate how polluted the air currently is or how polluted it is forecast to become. The AQI is based on the five "criteria" pollutants regulated under the Clean Air Act: ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide. The AQI also tracks particle pollution (tiny particles from smoke, power plants, factories, vehicle exhaust, and other sources).

The United States Environmental Protection Agency (EPA) establishes an AQI for the five major air pollutants regulated by the Clean Air Act. Each of these pollutants has a national air quality standard set by the EPA to protect public health. The EPA has established National Ambient Air Quality Standards (NAAQS) for each of these pollutants to protect public health. An AQI value of 100 generally corresponds to the level of the NAAQS for the pollutant. The Clean Air Act (USA) (1990) requires the EPA to review its National Ambient Air Quality Standards every five years to reflect evolving health effects. The Air Quality Index is adjusted periodically to reflect these changes.

The AQI breaks air pollution levels into six categories, each of which has a name, an associated color, and advice. AQI values at or below 100 are considered satisfactory for almost everyone. When AQI values are above 100, air quality is unhealthy. The higher the number, the more people are at risk of health harm. For example, an AQI value of 50 or below represents good air quality, while an AQI value over 300 represents hazardous air quality. For each pollutant, an AQI value of 100 generally corresponds to an ambient air concentration that equals the level of the short-term national ambient air quality standard for protection of public health.

On a day when the AQI is predicted to be elevated due to fine particle pollution, an agency or public health organization might advise sensitive groups, such as the elderly, children, and those with respiratory or cardiovascular problems, to avoid outdoor exertion. They may also declare an "action day" to encourage voluntary measures to curtail air emissions, such as using public transportation, or recommend the use of masks outdoors and air purifiers indoors to prevent fine particles from entering the lungs.

What are the sources of air pollution?

Air pollution is a mix of hazardous substances from both human-made and natural sources. There are four main types of air pollution sources: mobile, stationary, area, and natural sources. Mobile sources include cars, buses, planes, trucks, and trains. These sources account for more than half of all air pollution in the United States, with automobiles being the primary source. Stationary sources, such as power plants, oil refineries, industrial facilities, and factories, emit large amounts of pollution from a single location and are also known as point sources. Area sources are made up of multiple smaller pollution sources that may not be significant on their own but can contribute significantly when grouped. Examples include agricultural areas, cities, and wood-burning fireplaces. Natural sources include wind-blown dust, wildfires, and volcanic eruptions.

Vehicle emissions, fuel oils, and natural gas used for heating homes are major human-made sources of air pollution. The combustion of fossil fuels, such as gasoline and diesel, releases harmful pollutants into the air. Additionally, industrial processes and power generation, particularly coal-fueled power plants, contribute significantly to air pollution. The production and use of chemicals can also lead to air pollution, as fumes from chemical manufacturing contain hazardous substances.

Particulate matter (PM) is a significant component of air pollution. It includes fine particles such as sulfates, nitrates, carbon, or mineral dusts. Vehicle emissions, industrial activities, cigarette smoke, and burning organic matter, such as wildfires, release PM into the air. Fine particulate matter (PM2.5) is of particular concern as it can penetrate deep into lung tissue and contribute to serious health issues. Ozone (O3), formed by the reaction of pollutants in the presence of sunlight, is another critical air pollutant. Ground-level ozone, often referred to as smog, is a significant component of traffic-related air pollution (TRAP).

Natural sources of air pollution include wildfires, volcanic eruptions, and the release of gases from decomposing organic matter in soils, such as methane. While these sources are beyond human control, human activities can contribute to their occurrence, such as in the case of wildfires. Overall, air pollution has severe health implications, with exposure to PM2.5 being linked to increased mortality risks and various diseases, including cancer, cardiovascular disease, and respiratory illnesses.

What are the health risks of air pollution?

Air pollution is the presence of contaminants in the atmosphere, such as dust, fumes, gases, odours, smoke, or vapours, in quantities that can be harmful to human health. The main pathway of exposure to air pollution is through the respiratory tract, but some pollutants are so fine that they can penetrate the bloodstream via the lungs and circulate throughout the body, leading to systemic inflammation and carcinogenicity.

The health risks and disease pathways depend on the types and concentrations of pollutants in the air. Some of the most harmful pollutants include particulate matter (PM), carbon monoxide (CO), ozone (O3), nitrogen dioxide (NO2), and sulphur dioxide (SO2). Exposure to high levels of these pollutants can lead to respiratory infections, reduced lung function, aggravated asthma, and cardiac problems. Long-term exposure to fine particulate matter increases the risk of non-communicable diseases such as stroke, heart disease, chronic obstructive pulmonary disease, and cancer.

Children, the elderly, and pregnant women are more susceptible to air pollution-related diseases. Higher levels of air pollution are associated with an increased risk of short-term respiratory infections in children, leading to more school absences. Children living in low-income urban areas or near busy roads have a higher prevalence of asthma. Additionally, air pollution exposure during pregnancy increases the risk of adverse outcomes such as low birth weight, preterm birth, and postpartum depression in mothers.

Air pollution also disproportionately affects certain communities and demographic groups. People of colour, for example, are more likely to be exposed to air pollution and suffer more significant harm to their health. This disparity can be attributed to systemic racism and discriminatory practices that have led to the placement of sources of pollution, such as power plants and industrial facilities, in economically disadvantaged communities of colour.

How does air pollution impact the climate?

Air pollution and climate change are closely interconnected. Climate change impacts air quality, and certain air pollutants contribute to climate change. For instance, ground-level ozone, a greenhouse gas, is increased on hot sunny days associated with a warming climate. This ground-level ozone further contributes to climate change by trapping heat in the atmosphere.

Climate change has led to more frequent and longer wildfire seasons. Wildfire smoke, which can spread hundreds of miles, pollutes the air and can worsen respiratory illnesses such as asthma, COPD, and bronchitis. It has also been linked to premature births. Warmer temperatures, earlier springs, and longer summers can increase exposure to pollen and other airborne allergens, leading to more allergy-related illnesses.

Additionally, socially vulnerable groups, including low-income populations, communities of color, Indigenous populations, and immigrant groups, are disproportionately affected by air pollution. They are more likely to live in areas with high levels of air pollution and suffer from respiratory issues and heart disease. Climate-driven changes in weather conditions, such as temperature and precipitation, can further exacerbate these issues.

To reduce the impacts of air pollution on the climate, transitioning to renewable energy sources, improving fuel efficiency, and adopting electric vehicles are crucial. These measures not only limit air pollution but also curb the global warming that intensifies its detrimental health effects.

Air pollution has severe consequences for both human health and the planet. According to the World Health Organization (WHO), air pollution is responsible for nearly seven million deaths worldwide each year, with 99% of people breathing air that exceeds the WHO's guideline limits for pollutants. Therefore, addressing air pollution and its impact on the climate is essential for safeguarding public health and mitigating the effects of climate change.

What is being done to address air pollution?

Air pollution is a pressing issue that affects people's health and the environment. While great progress has been made in improving air quality since the 1970s, there is still much to be done to address this global challenge. Here are some key actions and initiatives that are being undertaken to tackle air pollution:

• Government Regulations and Policies: Many governments have implemented regulations and policies to reduce air pollution. For example, the United States' Environmental Protection Agency (EPA) has been working collaboratively with state, local, and tribal governments, as well as industries, under the Clean Air Act to reduce pollution from power plants, industrial facilities, vehicles, and other sources. The EPA has also established the Air Quality Index (AQI) as a tool to communicate about outdoor air quality and health risks to the public.
• Emissions Standards: Standards for vehicle emissions have been particularly effective in reducing air pollution. All vehicles and engines in the United States must comply with emissions standards for pollutants like smog, soot, and greenhouse gases, leading to improved fuel efficiency and reduced emissions. The Diesel Emissions Reduction Act (DERA) provides funding for owners to replace their diesel equipment, resulting in significant cuts in pollution and associated health benefits.
• Clean Energy Initiatives: The Clean Power Plan in the United States aims to reduce carbon pollution from power plants while maintaining energy reliability and affordability. The SmartWay Transport Partnership and SmartWay program empower companies to move goods in more energy-efficient ways, reducing carbon dioxide, nitrogen oxide, and particulate matter emissions.
• Community-Based Initiatives: Various community-based initiatives are making a difference at the local level. For example, the National Clean Diesel Campaign reduces diesel emissions from existing engines, Clean School Bus USA aims to minimize pollution from school buses, and the Minnesota GreenCorps addresses environmental issues, including air quality, through AmeriCorps programs.
• Education and Awareness: Organizations like the Environmental Defense Fund (EDF) and the Minnesota Pollution Control Agency (MPCA) focus on raising awareness and providing education to communities and businesses on reducing air pollution. The EDF provides in-depth reporting and insights on climate and environmental challenges, while the MPCA offers guidance and incentives to reduce air pollution through various programs.
• International Cooperation: Addressing air pollution requires global collaboration. Initiatives like the World Air Quality Index project provide real-time air quality data for over 80 countries, helping people worldwide understand the air pollution levels in their respective regions.

While these actions signify significant progress, continued efforts and innovations are necessary to combat air pollution and safeguard the health of people and the planet.

Frequently asked questions