Understanding the Effects of Outdoor Air Pollution on Public Health

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A coal-burning power plant spews smoke from massive chimneys.

Air pollution represents one of the gravest public health threats on the planet. Pollutants such as ozone, nitrogen dioxide, and carbon monoxide have been linked to a range of health problems, including cardiovascular and respiratory diseases, lung cancer, neurological disorders in children, and even premature death. According to a study from the Max Planck Institute for Chemistry and the University Medical Center Mainz in Germany, air pollution contributes to the deaths of more than 8 million people worldwide each year.

The majority of air pollution stems from the use of fossil fuels such as coal, oil, and natural gas. Researchers in the German study estimated that eliminating fossil fuel emissions would increase the average global life expectancy by more than a year.

Beyond its negative impact on human health, outdoor air pollution has further harmful effects. Toxic air pollutants contribute to birth defects and wildlife disease, can damage staple crops, and harm forest ecosystems. Air pollution also takes a significant toll on the global economy, costing nearly $3 trillion in 2018, according to the Center for Research on Energy and Clean Air.

Public health professionals play a critical role in stemming the tide against air pollution and its negative impacts. Through advocacy and education, those in public health roles can influence policy development aimed at reducing air pollution and mitigating its adverse health effects, and assist individuals and communities by collaborating with government agencies.

What Are the Causes of Outdoor Air Pollution?

Air pollution comes in many different forms, such as ozone and particulate matter from exhaust pipes or factory smokestacks. These pollutants enter the air when fossil fuels are burned and contain gases that degrade outdoor air quality.

Ozone, or Smog

Ozone in the upper atmosphere provides protection from the sun’s ultraviolet radiation, but at ground level it can be very dangerous. One of the most common causes of outdoor air pollution, ozone forms when nitrogen oxide and volatile organic compounds — produced by the burning of fossil fuels such as gasoline or coal — are exposed to sunlight. Ground-level ozone is the primary ingredient in smog, and the wind can disperse it long distances, exposing even rural areas to unsafe levels.

Particle Pollution

Particulate matter is a combination of tiny solid and liquid particles in the air that are made up of different compounds. Many particles are so small as to be virtually invisible, but high levels of particle pollution cause the air to become cloudy or hazy. Wildfire smoke and exhaust from car tailpipes are examples of particle pollution.

Toxic Substances

Toxic pollutants pose a serious threat to public health. They can take the form of gases such as hydrogen chloride, elements such as cadmium or mercury, or compounds such as asbestos. The U.S. Environmental Protection Agency (EPA) has identified 187 such toxic pollutants.

Burning fossil fuels such as coal or gas often releases a combination of toxic gases that’s detrimental to public health. Some of the most common types of residual gas are:

  • Nitrogen Dioxide: A key ingredient in many different forms of air pollution. In addition to its negative impact on breathable air, nitrogen dioxide can interact with oxygen, water, and other chemicals in the atmosphere to form acid rain.
  • Sulfur Dioxide: A gaseous air pollutant released when sulfur-containing fossil fuels are burned. Industrial processes are the largest source of sulfur dioxide pollution.
  • Carbon Monoxide: Burning fossil fuels such as gasoline and natural gas releases carbon monoxide, which is a colorless, odorless, tasteless gas. A number of home appliances, such as space heaters and gas stoves, release carbon dioxide, which can affect indoor air quality as well.

According to the State of Global Air Initiative, more than 90% of people worldwide are exposed to air pollution that exceeds World Health Organization (WHO) guidelines. However, certain areas are more polluted than others. Cities, for example, typically have higher ozone levels due to more vehicular traffic, manufacturing, industry, and other sources of emission. Urban areas are also subject to the “heat island” effect, in which the building materials used in cities — pavement and asphalt, for example — soak up and trap heat, leading to an increased demand for electricity, which in turn contributes to an increase in air pollution. Additionally, those who live near power plants, ports, or highways are exposed to greater levels of outdoor air pollution than the general population. Approximately 30% to 45% of people who live or work in U.S. cities are close enough to a busy roadway to experience significantly higher levels of pollution, according to the American Lung Association.

What Are the Sources of Outdoor Air Pollution?

Part of the challenge of combating outdoor air pollution is that it comes from many different sources. Fossil fuel combustion for power generation and transportation at the residential, commercial, and industrial levels all contribute to the deterioration of outdoor air quality to varying degrees.


Heating and cooling homes requires energy, and despite the increased proliferation of renewable sources, fossil fuels still produce much of that energy. Coal-fired electricity and natural gas are the most common energy sources in homes, leading to gaseous emissions such as nitrogen dioxide and sulfur dioxide, and contributing to ground-level ozone and particle pollution.

Commercial and Industrial

Providing power to large commercial and industrial structures such as offices, factories, supermarkets, and hospitals, requires tremendous amounts of energy, for both heating and cooling and manufacturing processes. Power plants burn fossil fuels such as coal, oil, and natural gas to generate electricity, releasing emissions such as sulfur dioxide, nitrogen dioxide, and carbon monoxide.


Emissions from cars, boats, and aircraft, whether they’re transporting products or people, also contribute significantly to air pollution. According to the U.S. Department of Energy, the total number of vehicle miles traveled — from cars, trucks, SUVs, and tractor trailers — exceeded 3 trillion in 2018. Burning gasoline and diesel fuel in combustion engines produces a range of pollutants, including particulate matter, nitrogen oxide, sulfur dioxide, and lead.

Improving fuel efficiency and pivoting from fossil fuels to renewable sources of energy such as solar and wind can reduce air pollution dramatically. The Clean Air Act, which sets emissions standards for hazardous air pollutants, has led to significant reductions in several common pollutants in the U.S. According to the EPA, since the Clean Air Act was adopted in 1970:

  • Tailpipe emissions from new passenger vehicles are 98% to 99% cleaner
  • Fuels are much cleaner, with the elimination of lead and a 90% reduction in sulfur dioxide
  • U.S. cities have significantly better air quality, despite increasing populations and more vehicle miles traveled

Natural Disasters and Wildfire Air Pollution

While fossil fuel combustion for transportation and energy production is the biggest source of outdoor air pollution, natural disasters such as wildfires and floods also contribute to harmful pollutants making their way into the air.


Wildfires are a major source of particle pollution, accounting for about 36% of fine particles in the air, according to the American Lung Association. Wildfire smoke leads to increased levels of carbon monoxide and nitrogen dioxide. In 2020, one of the worst years on record for wildfires, historic bushfires in Australia burned tens of millions of acres and caused hundreds of deaths from smoke inhalation. In the U.S., record-breaking wildfires on the West Coast burned more than 5 million acres, destroyed thousands of buildings, and caused dozens of deaths.

Hurricanes and Floods

Natural disasters such as hurricanes, tornadoes, and floods and the damage they cause can also be sources of air pollution. The disasters may knock out electricity, causing residents to turn to gasoline- or diesel-powered generators, gas or charcoal stoves, grills, and other devices for indoor heating or cooking, all of which burn fossil fuels that produce carbon monoxide. Additionally, storm damage may stir up dust, toxic-building materials, and other contaminants that are dangerous to breathe, and water damage promotes the growth of bacteria and mold, potentially triggering respiratory issues. One of the greatest dangers of outdoor air pollution is its impact on climate change. Fossil fuel combustion releases pollutants into the atmosphere, including greenhouse gases such as ozone and carbon dioxide, one of the biggest drivers of climate change. The emissions trap excess heat near the planet’s surface, leading to warmer temperatures on a global scale and fueling extreme weather events. According to NASA, 2020 tied with 2016 as the warmest year on record, continuing a concerning trend of ever-increasing global temperatures. It’s no coincidence then that the 2020 Atlantic hurricane season was the most active on record, with 30 named storms. Additionally, hotter temperatures and droughts from climate change have increased the frequency and intensity of wildfires, leading to increased levels of ozone and particle pollution, which further contributes to climate change in a vicious cycle.

Health Effects of Outdoor Air Pollution

An abundance of evidence links air pollution with a range of health issues. A 2019 EPA study found that particle pollution contributed to respiratory conditions, such as asthma, and cardiovascular concerns, including heart attacks and strokes, as well as higher rates of cancer and early death. The damaging effects of outdoor air pollution can also have an indirect impact on the economy.

Respiratory Issues

Exposure to ground-level ozone and pollutants such as sulfur dioxide and nitrogen oxide can cause numerous respiratory issues, including allergies, asthma attacks, diminished lung function, and increased risk of respiratory infection. Air pollution also poses a greater risk to those with existing respiratory conditions, such as chronic obstructive pulmonary disease (COPD) and emphysema. Researchers in New York found that children with chronic exposure to ozone were more likely to be admitted to hospitals for asthma.

Cardiovascular Issues

Air pollution also harms the cardiovascular system. Studies have shown that people exposed to air pollution are at greater risk of heart attack, heart disease, stroke, and even diabetes. Research has shown that long-term exposure to particle pollution, in particular, increases the risk of developing type 2 diabetes. Air pollution is considered a leading risk factor for death globally due to its contribution to many of the world’s leading causes of death, such as heart disease, stroke, and cancer.

Additional Effects of Outdoor Air Pollution

Air pollution can also have indirect impacts on public and economic health:

  • Health Care Costs and Decreased Productivity: The health effects of air pollution lead to increased hospital visits and more time taken off from work, taxing the health care system and reducing productivity.
  • Lost Crops: Air pollution damages staple crops, such as wheat, rice, and soybean, threatening global food security. According to a study by the UK Center for Ecology & Hydrology, ozone alone causes a 5% to 12% loss in staple crops globally each year.
  • Neurological Disorders: Evidence suggests that air pollution adversely affects brain development in children, potentially leading to developmental disabilities such as autism and attention deficit/hyperactivity disorder (ADHD), according to a report by Project TENDR, a collaboration of scientists, health professionals, and children’s health advocates. Air pollution has also been linked to premature birth and low birth weight.

Those in public health can help protect individuals and communities from the negative health impacts of air pollution by outlining the benefits of clean air and providing access to resources related to air quality, such as those from the EPA and National Weather Service.

How Public Health Professionals Address Outdoor Air Pollution

Public health professionals play a critical role in addressing the impact of air pollution by advising and collaborating with government leaders and decision-makers in the public and private sectors. They can use their expertise to influence policy development on curbing air pollution and shielding communities from its adverse effects. Decisions related to housing, transportation, and energy all have the potential to impact air pollution; therefore, engaging public health professionals in this process is crucial. A fundamental way public health professionals can help communities address outdoor air pollution is through the city/regional planning process. Those in public health understand how pollutants impact the population and can advise decision-makers on ways to reduce exposure, such as building schools, hospitals, and residential developments away from highways, factories, and other sources of emission.

Health professionals can also speak to the disproportionate impact that air pollution — and its associated health risks — has on disadvantaged communities to help guide planning decisions. Advocating for improved fuel efficiency standards or the use of renewable sources of energy are among other ways that public health professionals can influence healthy decision-making. Public buy-in is critical in the campaign against air pollution. Professionals in public health can also advocate for community involvement in the policymaking process. According to the EPA, this can streamline implementation and alleviate potential challenges down the line. Various public health organizations, such as the American Public Health Association and the Association of Public Health Laboratories, have collaborated with the EPA in recent years. This has led to improved outreach and training for local public health professionals, as well as enhanced public education campaigns around air pollution, including information on wildfires.

Striving for Improved Air Health

The task of reducing outdoor air pollution and protecting communities from its adverse health effects requires a multidimensional approach, and public health professionals are critical to that effort. Air pollution is a threat to individual health, contributing to conditions such as asthma, heart disease, and cancer, and can disproportionately impact disadvantaged communities. It also poses a threat to the health of the planet. Public health professionals can use their expertise to influence policies designed to curb air pollution and stem its negative health effects. Those interested in learning about the role public health professionals play in the fight against air pollution should explore Regis College’s online Master of Public Health program, where the Health Policy and Management concentration teaches the leaders of tomorrow how to advocate for policy change using community solutions to improve health outcomes and work toward social change.

Recommended Readings

8 Environmental Factors That Affect Health

What Can I Do After Earning an MPH?

Why Study Health Policy and Management?


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American Lung Association, Emergencies & Natural Disasters

American Lung Association, What Makes Outdoor Air Unhealthy

American Public Health Association, Climate Changes Health: Extreme Weather

BBC, Australia Bushfires: Hundreds of Deaths Linked to Smoke, Inquiry Hears

Center for Research on Energy and Clean Air, Quantifying the Economic Costs of Air Pollution from Fossil Fuels

Climate Central, Climate Change Is Threatening Air Quality Across the Country

Commonwealth of Massachusetts, Health & Environmental Effects of Air Pollution

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