Air Pollution In The Us: A Troubling Reality

Air pollution is a serious health threat in the United States, causing and exacerbating a range of health issues, from temporary ailments like dry coughs and sore throats to more serious conditions like pulmonary disorders, cancer, and even premature death. While air quality has improved nationally since 1980, with emissions of the six principal air pollutants dropping by 78% between 1970 and 2023, nearly half of Americans still live in areas with unhealthy levels of air pollution. This problem is disproportionately impacting communities of colour, who are more likely to be exposed to unhealthy air and suffer from the health consequences.

Air pollution's health effects

Despite improvements in air quality in the United States, air pollution continues to threaten the health and welfare of Americans. In 2023, about 66 million tons of pollution were emitted into the US atmosphere, and approximately 140 million people lived in counties with pollution levels above the primary NAAQS.

The health effects of air pollution range from temporary and superficial to life-threatening and terminal. Short-term exposure to air pollution can cause dry coughs, sore throats, and chest infections. Long-term exposure to air pollution can lead to more serious respiratory conditions, including chronic obstructive pulmonary disorder (COPD), pneumonia, bronchitis, emphysema, and aggravated forms of asthma. Air pollution has also been linked to an increased risk of lung cancer, even among those who have never smoked.

Particulate matter (PM) and ozone are two of the most widespread and dangerous air pollutants. Fine particulate matter (PM2.5) is known to increase the amount and seriousness of lung and heart disease and other health problems. Exposure to PM2.5 has been associated with an elevated risk of early death, primarily from cardiovascular and respiratory causes. It is also linked to an increased risk of death from lung cancer. Wildfires, which are becoming larger and more intense, contribute to air pollution and can cause eye and respiratory tract irritation, reduced lung function, exacerbation of asthma and heart failure, and premature death.

Certain populations are more vulnerable to the health effects of air pollution, including children, the elderly, pregnant women, and people with pre-existing lung and heart disease. Research has also shown that communities of color are disproportionately exposed to unhealthy air and are more likely to suffer harm to their health from air pollution. Psychosocial stressors, such as poverty and racial/ethnic discrimination, can also amplify the harmful effects of air pollution.

Air pollution by state

Air pollution is a serious health threat in the United States, affecting millions of people, especially children, older adults, and those with respiratory conditions such as asthma and COPD. People of color and low-income communities are disproportionately impacted by air pollution, putting them at higher risk for illness. The main sources of air pollution in the US include emissions from industrial facilities and vehicles, as well as airborne particles such as smoke and dust.

While the national air quality in the US has improved over the past few decades due to federal and state regulations, there are still several states that struggle with poor air quality. According to the American Lung Association's "State of the Air" report in 2025, nearly half of the US population lives in areas with failing grades for either ozone or particle pollution. More than 42 million people reside in counties that received failing grades for all three air pollution measures.

Some of the states with the worst air quality include:

• Arizona: With 62% of the population living in Maricopa County, the air quality in this county significantly impacts the state's overall air quality. Wildfires also contribute to the state's worsening air quality.
• North Dakota
• Wyoming
• California: Yosemite Lakes, California, was ranked as the most polluted city in the US by the IQAir website in 2020, with an AQI of 107.

On the other hand, states like New Hampshire, Maine, and New Mexico are considered some of the safest from pollution. New Mexico, in particular, has more than one-third of its land protected by the federal government, including national parks and historic sites.

To address air pollution, the US Environmental Protection Agency (EPA) plays a critical role in monitoring and regulating air quality. The EPA establishes the Air Quality Index (AQI) for major air pollutants and sets national air quality standards to protect public health. However, the EPA faces challenges due to significant staffing and funding cuts.

Air pollution by city

According to the American Lung Association's 2024 State of the Air Report, six of the top seven most polluted cities in the US are in California, with four in the state's Central Valley. Bakersfield, California, has the worst short-term particle pollution in the country for the third year in a row and the worst level of year-round particle pollution for the sixth consecutive year. Other cities in the Central Valley that made the list include Visalia and Fresno, located at the drier and hotter southern end of the valley, which is worse for air quality.

Los Angeles is the city with the worst ozone pollution in the US, an issue that has been recorded in 25 of the 26 years of reporting in the State of the Air Report. However, residents of Los Angeles are exposed to fewer days with unhealthy levels of ozone per year than they were in 2000.

The State of the Air Report looks at two of the most widespread and dangerous air pollutants: fine particles and ozone. The report uses air quality data collected at official monitoring sites across the US by federal, state, local, and Tribal governments. The Lung Association calculates values reflecting the air pollution problem and assigns grades for daily and long-term measures of particle pollution and daily measures of ozone.

Despite progress in air quality improvement, approximately 140 million people nationwide lived in counties with pollution levels above the primary NAAQS in 2023. Air pollution is a complex mixture of gases, particles, and liquid droplets, with a variety of sources, including wildfires and cookstoves in rural areas, and road dust and diesel exhaust in cities. Some of the chemical pollutants released from combustion sources include nitrogen dioxide and sulfur dioxide, which are largely released through vehicular emissions.

Air pollution by year

Air pollution is the release of pollutants into the atmosphere that are detrimental to human health and the planet. According to the World Health Organization (WHO), air pollution is responsible for nearly seven million deaths worldwide each year.

In the United States, the Clean Air Act, established in 1970, empowers the Environmental Protection Agency (EPA) to regulate the emission of harmful air pollutants. Over the years, the EPA has made significant progress in improving air quality in the US. Since 1970, the combined emissions of the six common pollutants (PM2.5 and PM10, SO2, NOx, VOCs, CO, and Pb) have dropped by 78%.

Despite these improvements, air pollution remains a pressing issue. In 2021, approximately 102 million Americans lived in counties with air quality concentrations above the level of one or more National Ambient Air Quality Standards (NAAQS). The number of people exposed to unhealthy air quality increased to 140 million in 2023 and 156.1 million in 2025, according to the American Lung Association's "State of the Air" report. This increase can be partly attributed to extreme heat, drought, and wildfires, which contribute to higher levels of ozone and particle pollution.

Yearly variations in air quality are influenced by pollution emissions, natural events such as dust storms and wildfires, and weather variations. For instance, while CO2 emissions showed an overall decreasing trend since 2007, they were 17% higher in 2022 than in 1970.

To address air pollution, the EPA works collaboratively with state, local, and tribal agencies to identify areas that do not meet the NAAQS. The EPA also provides a daily Air Quality Index (AQI) forecast to help people protect their health. Additionally, the United States signed the Kigali Agreement in 2022, committing to reducing the use of hydrofluorocarbons (HFCs) and developing greener alternatives.

Air pollution by cause

Air pollution in the United States has improved since 1980, but it continues to harm people's health and the environment. In 2023, about 66 million tons of pollution were emitted into the US atmosphere. Despite improvements, approximately 140 million people lived in counties with pollution levels above the primary NAAQS in the same year.

Transportation

The US Environmental Protection Agency (EPA) estimates emissions from vehicles, and these estimates are based on factors such as vehicle miles traveled and fuel consumption. Vehicle emissions are a major source of nitrogen dioxide (NO2) and sulfur dioxide (SO2).

The Clean Air Act has helped reduce emissions from transportation, with the EPA and the National Highway and Traffic Safety Administration issuing the first national greenhouse gas emission standards and fuel economy standards for cars and light trucks for model years 2012-2025.

Power Plants

Power plants are another significant source of air pollution, and the Clean Power Plan aims to reduce carbon pollution from existing power plants while maintaining energy reliability and affordability. The plan sets customized goals for states to cut carbon pollution and provides a level playing field for energy sources.

Manufacturing and Industry

Emissions from manufacturing and other industrial sources have also decreased over time due to the Clean Air Act. However, industrial activity and technological developments can still contribute to air pollution. For example, emissions of lead compounds have decreased due to the phase-out of leaded gasoline and the EPA's air toxics program.

Wildfires

Climate change and extreme weather conditions have increased the risk of wildfires, which release dangerous particle pollution and ozone-forming pollutants. The “State of the Air" report in 2025 noted that a heatwave in Texas and wildfires in Canada drove levels of ozone and particle pollution in central and eastern states to their highest levels in years.

Construction and Mining

Disruption of large amounts of earth or rock through processes such as mining, extraction, and construction can release particulate matter (PM10 or PM2.5) into the air.

Overall, while air quality in the United States has improved in recent decades, air pollution remains a serious health threat, and continued efforts are needed to reduce emissions and protect public health.

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