Air Pollution In America: How Many Are Affected?

Despite the Clean Air Act of 1970, which has improved air quality in the United States, millions of Americans still breathe polluted air. According to the American Lung Association's State of the Air report in 2025, approximately 46% of Americans, or 156 million people, live in areas with unsafe levels of ozone, particulate pollution, or both. This is a significant increase from the previous year and is attributed to climate change and the Trump administration's environmental rollbacks. The report also highlights racial inequities, with people of color being more likely to live in areas with unhealthy air quality. While the situation in the United States is concerning, it is part of a global issue, as the World Health Organization (WHO) has warned that almost everyone worldwide breathes polluted air, exceeding internationally approved limits.

Air pollution's negative health impacts

According to the American Lung Association's annual State of the Air report, almost half of Americans—approximately 156 million people—are exposed to unsafe levels of air pollution. This includes ozone pollution and particulate pollution, both of which can have detrimental effects on human health.

Ozone pollution, or smog, is a ground-level mixture of harmful pollutants, primarily nitrogen oxides and volatile organic compounds. When inhaled, ozone irritates the respiratory tract, causing inflammation and oxidative stress, which can lead to asthma attacks and other respiratory issues. It also increases the risk of heart attacks and strokes, preterm births, and impaired cognitive functioning later in life.

Particulate pollution, or particle pollution, refers to a mixture of solid particles and liquid droplets in the air. These particles, especially those with a diameter of 2.5 µm or less (PM2.5), can be inhaled and are so small that they can penetrate deep into the lungs, enter the bloodstream, and travel to various organs, causing systemic damage to tissues and cells. This can result in lung cancer, heart disease, and other serious health conditions. Fine particulate matter (PM2.5) is considered the air pollutant with the most severe health implications and has been linked to premature mortality.

Additionally, air pollution has been associated with an increased risk of all-cause mortality and specific diseases. It can affect almost every organ in the body, leading to systemic inflammation and even carcinogenicity. The World Health Organization (WHO) has found links between exposure to air pollution and various health issues such as type 2 diabetes, obesity, Alzheimer's disease, and dementia.

Certain populations are more vulnerable to the adverse health impacts of air pollution. For instance, people of colour, particularly Latino Americans, are more likely to be exposed to toxic air pollutants. Socio-economic status also plays a role, with lower socio-economic status often correlating with increased exposure to air pollution. Older individuals, children, and those with pre-existing health conditions are more susceptible to the detrimental effects of air pollution.

Climate change's role in worsening air quality

According to the American Lung Association's annual State of the Air report, about 46% of Americans (approximately 156 million people) live with unsafe levels of ozone, particulate pollution, or both. This is a significant issue, as breathing polluted air can lead to both acute and chronic health conditions, including an increased risk of early death.

Climate change plays a significant role in worsening air quality. Atmospheric warming associated with climate change can increase ground-level ozone, a greenhouse gas and health hazard, in many regions. Warmer temperatures also contribute to increased pollen production, lengthening the pollen season. These airborne allergens, including pollen, decrease air quality and cause respiratory problems such as asthma and allergies.

Additionally, climate change can lead to more frequent and severe heat waves, which further increase ground-level ozone pollution. During heatwaves, stagnant air can trap air pollutants in specific areas, further degrading air quality. Moreover, prolonged periods of high temperatures can lead to drought conditions, increasing the risk of wildfires. Wildfire smoke contains harmful substances such as carbon monoxide and particulates, which negatively impact air quality and contribute to respiratory illnesses.

The impact of climate change on particulate matter is also significant. Drought conditions can increase particulate matter in the air, causing air quality issues. Dust from droughts and windblown dust from wildfires can contribute to this increase in particulate matter, further worsening air pollution.

Furthermore, climate change can affect indoor air quality. Increases in outdoor air pollutants, such as ozone and particulate matter, can lead to higher indoor exposures. Climate change-related precipitation and storms can also increase indoor pollutants such as mold, dust mites, and bacteria.

It is important to recognize that the relationship between climate change and air quality is complex and bidirectional. While climate change worsens air quality, certain air pollutants, such as greenhouse gases, also contribute to climate change. Therefore, addressing air pollution and mitigating climate change are closely linked challenges that require urgent attention and action.

Racial disparities in air quality

According to the American Lung Association's annual State of the Air report, about 46% of Americans (approximately 156 million people) live with unsafe levels of air pollution. This includes exposure to ozone, particulate pollution, or both. While this is a concerning figure in itself, the issue of air pollution disproportionately affects certain racial and ethnic groups, exacerbating existing inequalities and raising serious health concerns.

Hispanic, Black, and Latino Americans are among the most impacted by poor air quality. Research has shown that these racial and ethnic groups are more likely to reside in counties with higher levels of particle pollution and ozone pollution. A 2012 study found that unemployed individuals, those with low incomes or less education, and non-Hispanic Blacks were more likely to live in areas with higher particle pollution exposure. Furthermore, a person of color is more than twice as likely as a white American to live in a neighborhood with unhealthy levels of smog and soot, with Latino Americans being three times more likely to breathe in toxic air pollutants.

The reasons for these disparities are complex and multifaceted. One factor is residential segregation, which has resulted in African Americans and other people of color living in areas with greater exposure to air pollution. Additionally, socioeconomic status plays a role, with low socioeconomic status increasing the risk of premature death from fine particle pollution. However, it is important to note that higher-income Blacks still face greater health risks than lower-income whites, indicating that income is not the sole driver of these disparities. Other factors, such as chronic stress due to discrimination, may also contribute to the increased health risks faced by racial and ethnic minorities.

Addressing these racial disparities in air quality requires action at multiple levels. While the Clean Air Act enacted in 1970 has led to overall improvements in air quality, weakening or rolling back environmental regulations could exacerbate the problem. Efforts to strengthen and enforce environmental protections are crucial to mitigate the impact of air pollution on vulnerable communities. Additionally, integrating multiple data sources and improving the spatial distribution of regulatory air quality monitors can help fill monitoring gaps and ensure equitable representation of air quality data for marginalized racial and ethnic groups. By recognizing and addressing these disparities, we can work towards creating a healthier and more equitable environment for all.

Wildfires' impact on air pollution

According to the American Lung Association's annual State of the Air report, about 46% of Americans, or 156 million people, live with unsafe levels of ozone, particle pollution, or both. This is a significant issue, as air pollution can have severe health consequences, including an increased risk of early death and various acute and chronic health conditions. While air quality in the United States has generally improved since the Clean Air Act of 1970, with key pollutant levels dropping by nearly 80%, wildfires continue to be a significant contributor to air pollution and a concern for public health.

Wildfires release a mixture of gaseous pollutants, hazardous air pollutants (HAPs), water vapour, and particle pollution, which is the main component of wildfire smoke. Particle pollution includes solid and liquid droplets suspended in the air, with sizes ranging from ultrafine particles smaller than 0.1 micrometres to larger particles up to 10 micrometres in diameter. These particles can be generated from mechanical operations and combustion-related activities, with wildfires being a significant source of fine particles.

The health effects of particle pollution from wildfire smoke have been well-documented, and they are comparable to the health impacts of particle pollution from other sources. These fine particles can penetrate deep into the lungs, and the smallest particles can even enter the bloodstream. The association between particle pollution and heart and lung health issues is particularly concerning, with an increased risk of heart attacks, strokes, and lung cancer. Wildfire smoke can also contain cancer-causing substances and aggravate existing health problems.

The impact of wildfires on air pollution extends beyond the immediate vicinity of the fires. Smoke from wildfires can travel hundreds of miles, affecting individuals even if they are not near an active fire. This was evident in June 2023 when wildfires in Canada caused a decline in air quality as far away as New York City. To protect themselves from the harmful effects of wildfire smoke, individuals are advised to stay indoors with closed windows and doors and use air conditioning with recirculation modes to prevent outdoor smoke from entering.

Progress in reducing air pollution sources

According to the American Lung Association's annual State of the Air report, about 46% of Americans (approximately 156 million people) live with unsafe levels of air pollution. This includes ozone pollution and particulate pollution, which can cause serious health issues such as asthma attacks, heart attacks, strokes, preterm births, cognitive impairment, and lung cancer. Despite this, there has been notable progress in reducing air pollution sources over the years.

The Clean Air Act, enacted in 1970, has played a significant role in improving air quality in the United States. Since its implementation, levels of key pollutants have dropped by nearly 80%. The Act has prompted the deployment of clean technologies and innovations that reduce emissions and control costs. For example, sulfur in gasoline has been reduced by 90%, and sulfur in diesel fuel by 99%, from pre-regulation levels. The Act also ensures that new industrial facilities are designed with good pollution control measures, making the country's industrial base cleaner over time.

The Environmental Protection Agency (EPA) has taken significant steps to limit emissions and protect public health. They have issued emissions standards for 174 categories of major sources, such as chemical plants and oil refineries, and 68 categories of small "area" sources responsible for 90% of the worst urban toxic pollutants. The EPA has also addressed interstate air pollution and reduced mobile and industrial pollution sources, resulting in significantly less toxic pollution released into the air compared to 1990.

Additionally, the Cross-State Air Pollution Rule, which came into effect in 2015, aimed to meet the 1997 ozone National Ambient Air Quality Standards (NAAQS). The EPA further revised this rule in 2016, known as the CSAPR Update, to reduce NOX emissions from power plants in the eastern US and help downwind states meet ozone standards. Power plants, which are a significant source of mercury emissions, have been required to reduce their emissions of mercury and other toxic pollutants since 2015, protecting Americans from various illnesses and premature deaths.

At the community level, organizations like the Minnesota Pollution Control Agency (MPCA) provide education, guidance, and incentives to reduce air pollution. They offer programs that address environmental problems, encouraging the use of electric vehicles, energy-efficient appliances, and promoting sustainable practices among local businesses and residents.

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