Air Pollution: Which State Suffers The Most?

Air pollution is a serious issue in the United States, with more than 42 million people living in counties that received an F for all three air pollution measures in State of the Air 2025. While air pollution is a widespread problem, some states are more polluted than others due to a variety of factors such as industrial emissions, fires, and chemical interactions in the atmosphere. The type of pollution that is often considered when talking about air pollution is particle pollution, which includes solid and liquid particles, and ozone levels, which are created by pollutants that react chemically with sunlight and can have negative health impacts. States with consistently poor air quality include Pennsylvania, Alabama, Louisiana, and California.

California's air pollution

California has some of the worst air pollution in the country. The state's large population of 39 million, significant port industry, and growing economy create significant emissions from traffic, diesel trucks, construction, agriculture, and domestic sources. California's mountainous terrain traps pollution, and its warm climate contributes to ozone formation, further exacerbating the problem.

The activities of California's large population contribute significantly to the state's air pollution. With over 39 million people, California is one of the most populous states in the country. The state's booming economy, including its large port industry and thriving tech and entertainment sectors, also contribute to high emissions levels. The state's unique geography, with its mountainous terrain, further exacerbates the problem by trapping pollution in certain areas.

The combination of these factors has resulted in California's poor air quality, which has severe health implications for its residents. A 2010 study by the California Air Resources Board estimated that PM2.5 pollution causes over 9,200 deaths in the state each year, with a statistical range of 7,300 to 11,000 deaths. The pollutants prevalent in California are linked to various health issues, including asthma, lung cancer, birth complications, and premature death.

To combat this issue, California has some of the most stringent air pollution rules in the nation, particularly in the Los Angeles basin. The state has a history of addressing severe air pollution, with the creation of the Mulford-Carrell Air Resources Act in 1967, which formed the California Air Resources Board. More recently, the Biden administration set new, more rigorous standards for fine particles, commonly called soot, which have plagued the state for decades. However, California officials acknowledge that they need help from the federal government to control some of the biggest sources of soot, including aircraft, trains, and ships.

California's pursuit of clean air is an ongoing challenge, with the state's frequent and severe wildfires, driven by climate change, presenting additional obstacles. The wildfire season of 2020, for example, contributed to some of the most severe wildfires in recent years, significantly impacting the state's air quality. As human-driven climate change continues to intensify wildfires, California's air quality is likely to worsen in the future.

Utah's air quality

The American Lung Association (ALA) ranked the Salt Lake City-Provo-Oren area as 9th worst for ozone air quality and 19th for short-term particle pollution in the US for 2024. Logan, another city in Utah, was ranked the 21st worst for short-term particle pollution. Of the 14 counties with ozone data from 2020 to 2022, 6 received an "F" grade, and 6 out of 10 counties monitored received an "F" for particulate matter.

The poor air quality in Utah has significant health impacts. A Utah Physicians for a Healthy Environment study estimated that there are 1,000-2,000 deaths in the state each year due to poor air quality. Fine particulates, especially those with diameters of 2.5 μm or less (PM2.5), can enter deep into the lungs, causing or worsening respiratory issues and reducing lung function. These particulates can also enter the bloodstream, leading to an increased risk of heart attacks, strokes, and irregular heartbeats. Furthermore, PM2.5 can cross the blood-brain barrier and contribute to degenerative brain diseases such as dementia and Alzheimer's, mental illness, and reduced intelligence.

To improve air quality in Utah, especially during inversions, there are restrictions on burning wood fires, with fines starting at $150 for first-time offences in Salt Lake County. Encouraging the use of carpooling and public transit, reducing vehicle idling, and promoting the use of newer, clean fuel vehicles can also help reduce emissions. Additionally, less use of gas-powered equipment and materials with high volatile organic compound (VOC) emissions, such as certain paints, can contribute to cleaner air throughout the year.

Climate change impact

Climate change and air pollution are closely interconnected, with climate change worsening air quality and certain air pollutants contributing to climate change.

Climate change has led to an increase in the frequency and duration of wildfires, which emit smoke that spreads pollutants over vast areas, impairing visibility, disrupting outdoor activities, and causing respiratory issues, especially in vulnerable individuals. Warmer temperatures and changes in precipitation patterns associated with climate change can also increase pollen and other airborne allergens, leading to more allergy-related illnesses.

Air Pollutants and Climate Change

Certain air pollutants, such as methane and black carbon, are short-lived climate pollutants (SLCPs) with a significant global warming potential. Black carbon, a component of particulate matter, absorbs sunlight, contributing to the warming of the Earth's atmosphere and accelerating the melting of snow and ice. Methane, a potent greenhouse gas, is a precursor to ozone, another air pollutant that affects weather processes and reduces agricultural yields.

Social and Environmental Vulnerability

The impacts of climate change on air quality disproportionately affect socially vulnerable groups, including low-income communities, communities of color, Indigenous populations, and immigrants. These groups often reside in industrial or urban areas with high levels of air pollution and are more susceptible to health issues such as heart disease, asthma, and chronic obstructive pulmonary disease (COPD). Additionally, they may live in older, poorly sealed buildings, increasing their exposure to outdoor allergens and pollutants, and making them more vulnerable to the effects of extreme weather events.

Mitigation Strategies

Mitigating climate change and improving air quality are closely linked. Strategies such as transitioning to renewable energy sources, reducing vehicle emissions, and adopting clean cooking technologies can simultaneously reduce air pollution and greenhouse gas emissions, offering health and climate benefits. The development of modeling tools, such as the EPA's GLIMPSE and CMAQ models, also assists in understanding and managing the impacts of energy technologies and air pollution on the environment.

Air Quality Index (AQI)

The Air Quality Index (AQI) is a tool used by the Environmental Protection Agency (EPA) to communicate about outdoor air quality and health. The AQI includes six colour-coded categories, each corresponding to a range of index values. The higher the AQI value, the greater the level of air pollution and the greater the health concern.

An AQI value of 50 or below represents good air quality, while an AQI value over 300 represents hazardous air quality. AQI values at or below 100 are generally considered satisfactory. When AQI values are above 100, air quality is unhealthy, initially for certain sensitive groups of people, and then for everyone as AQI values increase.

The AQI is calculated based on 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. These pollutants include ozone and particle pollution, which can have significant impacts on human health. Ozone can irritate the lungs, causing inflammation, while particle pollution has been linked to an increased risk of lung cancer, heart attacks, strokes, and early death.

According to the American Lung Association, nearly half of the people in the United States live in areas where the air quality received a failing grade in the "State of the Air" report for 2025. More than 156 million people reside in counties that received a failing grade for either ozone or particle pollution, and over 42 million people live in counties that failed all three air pollution measures.

While the Clean Air Act has driven pollution reduction for over 50 years, recent staffing and funding cuts to the EPA threaten its ability to continue monitoring and enforcing air quality standards. Despite these challenges, some cities, like New York, have shown improvements in air quality over the past several decades, with New York's AQI remaining below 50 or "good" for the last three years.

Lung health risks

Air pollution is anything that makes the air more toxic and damaging to our health. It can affect all parts of our bodies, including the health of our lungs, heart, and brain. According to the World Health Organization, almost nine out of ten individuals living in urban areas are affected by air pollution. Outdoor air pollution constitutes one of the leading global health risks and is responsible for 3.2 million deaths each year.

Children are more vulnerable to the effects of air pollution than adults because their lungs are still developing. They also breathe faster, which means they take in more polluted air. Exposure to air pollution during childhood increases the risk of developing asthma, COPD, and other respiratory infections as an adult. Prolonged exposure to air pollution during childhood can also cause reduced lung function and enhanced airway reactivity in children suffering from asthma. Older people are also more at risk, especially if they have long-term lung conditions or heart disease. If you are pregnant, air pollution can affect your unborn baby, increasing the likelihood of them developing asthma.

Air pollution is also linked to an increased risk of developing lung cancer. Particulate matter, nitrogen dioxide, ozone, and sulphur dioxide are particularly damaging types of air pollution. PM2.5 particles can reach the breathing sacs in your lungs, and ultrafine particles can cross into your bloodstream. These particles can carry toxic chemicals that are linked to cancer. High levels of NO2 can irritate the lining of your airways and make them more inflamed, increasing your risk of asthma attacks and COPD flare-ups. Radon gas and smoke from burning domestic fuels further elevate lung cancer risk when exposed over extended periods.

Climate change increases the risk of wildfires, which produce smoke that spreads dangerous particle pollution. The Clean Air Act has driven pollution reduction in the United States for over 50 years, and the Environmental Protection Agency (EPA) plays a critical role in monitoring and reducing air pollution. However, staffing and funding cuts endanger the EPA's ability to protect people's health from air pollution.

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