Air Pollution In America: A Comprehensive Overview

Air pollution in the United States of America is a pressing issue, with a recent report by the American Lung Association (ALA) revealing that almost 156 million people (46% of Americans) live in areas with unsafe levels of air pollutants. This is a 16% increase from the previous year, making it the highest number in a decade. The report also highlights the disproportionate impact of air pollution on people of colour, who are 61% more likely to reside in counties with failing grades for air quality. Climate change-fuelled events such as wildfires and extreme heat waves further exacerbate the problem, endangering the health of millions. The EPA, tasked with safeguarding Americans from air pollution, faces challenges due to funding cuts and rollbacks on environmental regulations.

Air pollution sources in Chicago

Chicago, the third most populous city in the United States, faces significant air pollution challenges due to its status as a major transportation hub. The city's air quality is impacted by various sources, which contribute to its ranking as the 18th most polluted city in the nation. Here are the key sources of air pollution in Chicago:

Transportation and Vehicle Emissions:

Chicago's position as a national crossroads for rail, road, and air traffic significantly contributes to its air pollution levels. The city has the most federal highways, one of the busiest airports in the world (O'Hare International Airport), and a vast network of trains, boats, automobiles, and locomotives. Emissions from diesel transport, passenger vehicles, and planes are primary sources of air pollution in the city.

Industrial Sources:

Chicago's industrial sector also plays a role in its air pollution levels. Emissions from industrial buildings and coal-fired power plants release pollutants into the atmosphere, including soot and tiny particles that can have detrimental health effects.

Domestic Heating and Winter Wood Burning:

Residential emissions from domestic heating sources, particularly during the winter months, contribute to air pollution in Chicago. Wood-burning devices and winter wood burning are significant sources of fine particle pollution, which can have health implications for residents.

Temperature Inversions:

Chicago's location on the shore of Lake Michigan makes the city prone to temperature inversions, specifically cool air inversions and marine inversions. These weather events can trap cooler air from the lake under a layer of warm air, preventing the dispersal of pollutants and exacerbating air quality issues.

Ground-Level Ozone (Smog):

Chicago has struggled with ground-level ozone pollution, commonly known as smog. In 2019, the city had a weighted average of 14 unhealthy ozone days between 2015 and 2017, higher than the average of 9.8 unhealthy days in the previous report. Ozone pollution, exacerbated by hotter days, poses risks to public health and can increase the likelihood of premature death, lung cancer, asthma attacks, and cardiovascular damage.

Addressing these sources of air pollution is crucial for improving the air quality in Chicago and protecting the health and well-being of its residents.

Climate change and air pollution

One of the key ways climate change impacts air pollution is by increasing the number of "bad air days". Hot, sunny days associated with a warming climate can elevate ground-level ozone levels, a harmful greenhouse gas that traps heat in the atmosphere. This ground-level ozone is a primary component of smog, which is formed when pollution from power plants, vehicles, and other sources reacts in the presence of sunlight. As a result, climate change can lead to more frequent and severe smog episodes, posing risks to respiratory health, particularly for individuals with asthma or allergies.

Additionally, climate change prolongs the pollen production season, intensifying pollen-related allergies and potentially triggering asthma attacks. Wildfires, which are becoming more frequent and severe due to climate change, release smoke that reduces air quality and endangers human health. Furthermore, extreme weather events, such as flooding, can result in water damage to buildings, creating conditions conducive to the growth of harmful pollutants like mold and bacteria.

The impacts of climate change on air quality vary regionally. For example, the Southwest experienced a severe long-term drought in 2021, which increased particulate matter and exacerbated air quality issues. Meanwhile, the geographic distribution of air pollution in the US has shifted, with the West Coast experiencing improved conditions in recent years, while other regions, like Illinois, have seen increases in ozone pollution.

To address these challenges, it is crucial to reduce air pollution and mitigate climate change. This includes implementing existing climate policies, such as the Clean Power Plan, and transitioning away from fossil fuels towards cleaner energy sources. By tackling these interconnected issues, we can improve air quality, protect public health, and build a more sustainable future for generations to come.

Air pollution and health

Air pollution in the United States has been a persistent issue, with far-reaching health implications for Americans. While there has been progress in reducing emissions of certain air pollutants, the problem persists and is evolving. Climate change, including rising temperatures, drought, and wildfires, is exacerbating air pollution and making it harder to mitigate.

The US Environmental Protection Agency (EPA), established in 1970, plays a crucial role in monitoring and regulating air pollution. Despite their efforts, air pollution continues to harm human health. According to the American Lung Association's 2025 report, nearly 156 million Americans live in areas with dangerous levels of air pollution, including cities like Bakersfield, Fresno, Los Angeles, San Francisco, Detroit, Cleveland, Houston, and Fairbanks. This is a 16% increase compared to the previous year, indicating a worsening trend.

The health impacts of air pollution are significant and wide-ranging. Short-term exposure to ozone pollution can trigger asthma attacks and cause chest pain, while long-term exposure can lead to decreased lung function and even premature death. Particle pollution, consisting of tiny particles that can bypass the body's defences, poses a serious threat to human health. Soot and smog, for instance, can increase the risk of asthma attacks, heart attacks, strokes, preterm births, and impaired cognitive functioning later in life. Warmer temperatures further contribute to the formation of ozone and make it more challenging to mitigate.

Certain demographic groups are disproportionately affected by air pollution. People of colour, particularly Latino Americans, are more likely to live in neighbourhoods with unhealthy air quality. According to the report, they are twice as likely as White people to reside in communities with failing grades for particle or ozone pollution. Additionally, those identifying as Hispanic are three times more likely than White people to live in areas with three failing grades for air pollution. This disparity underscores the environmental justice issues associated with air pollution.

The EPA has faced significant challenges due to proposed deregulation and funding cuts. The Trump administration's environmental rollbacks, including potential changes to the National Ambient Air Quality Standards for Particulate Matter, have raised concerns among health professionals. These changes could make it more difficult to protect public health and lung health, especially for those already vulnerable to the effects of air pollution.

Air pollution and environmental racism

Despite great progress in air quality improvement in the US, approximately 140 million people nationwide lived in counties with pollution levels above the primary NAAQS in 2023. According to the American Lung Association's annual State of the Air report, released in April 2025, almost half of Americans live in areas with a failing grade for air pollution. The report also noted that air pollution levels are worsening for more people in the US, and experts attribute this to the Trump administration's proposed deregulation plans.

People of colour are much more likely to live near polluters and breathe polluted air, even as agencies like the Environmental Protection Agency (EPA) seek to roll back regulations on pollution. A 2021 study by researchers at the EPA-funded Center for Air, Climate, and Energy Solutions found that people of colour breathe more particulate air pollution on average, regardless of income levels and regions of the US. This expands on a body of evidence showing that African Americans, Hispanics, Asians, and other people of colour are disproportionately exposed to a regulated air pollutant called fine particulate matter (PM2.5). Exposure to PM2.5 can cause serious health issues, including lung and heart problems, especially for vulnerable populations such as those with chronic diseases, younger people, and older adults.

A 2016 study in Environment International further linked long-term exposure to the pollutant with racial segregation, finding that more highly segregated areas suffered higher levels of exposure. Additionally, a 2012 article in Environmental Health Perspectives revealed that overall levels of particulate matter exposure for people of colour were higher than those for white people. For example, Hispanic people faced rates of chlorine exposure more than double those of white people, which is known to degrade cardiac function.

The findings of these studies indicate the presence of environmental racism, where racial-ethnic exposure disparities continue to persist even with an overall decrease in exposure. As co-author of the 2021 study, Julian Marshall, a professor of civil and environmental engineering at the University of Washington, stated, "The inequities we report are a result of systemic racism: Over time, people of color and pollution have been pushed together, not just in a few cases but for nearly all types of emissions."

Air pollution and the EPA

Air pollution in the United States has been a pressing issue, with approximately 140 million people living in counties with pollution levels above the primary National Ambient Air Quality Standards (NAAQS) in 2023. The US Environmental Protection Agency (EPA) plays a crucial role in addressing this issue and protecting people's health.

The Clean Air Act, first enacted in 1970, is the primary legislation that defines the EPA's responsibilities for improving the nation's air quality. The Act has been amended over the years to address emerging pollution threats and has led to significant reductions in air pollution. For instance, the permanent phase-out of leaded gasoline and controls on emissions of lead compounds through the EPA's air toxics program have resulted in a 98% decrease in airborne lead concentrations between 1980 and 2005.

The EPA works in collaboration with state, local, and tribal governments, as well as federal agencies and stakeholders, to implement the Clean Air Act and reduce air pollution. They estimate emissions of ambient air pollutants and their precursors, such as vehicles, factories, and other sources, using monitored readings and engineering calculations. The EPA has also developed national programs to achieve significant reductions in air emissions, benefiting public health and quality of life.

Despite the progress made, air pollution remains a challenge. Climate change has contributed to extreme weather events, leading to increases in high ozone days and spikes in particle pollution. Additionally, transportation, power plants, and manufacturing continue to be significant sources of pollution. The EPA faces threats such as staffing and funding cuts, which endanger their ability to protect public health effectively.

To address these challenges, the EPA has revised standards for common pollutants, taking into account new scientific studies. They provide guidance and issue federal emissions standards for new motor vehicles, industrial equipment, and state implementation plans. The EPA's efforts are crucial in the ongoing fight against air pollution, ensuring that clean air and a healthy economy can go hand in hand.

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