The American Lung Association’s 2025 Air Quality Report Written by: Ellie Sundali Updated: 2025-06-06 Read time: 16 minutes Each year, the American Lung Association releases its State of the Air report — a comprehensive analysis of air quality across the United States that evaluates exposure to two major pollutants: ground-level ozone (commonly known as smog) and fine particulate matter (PM2.5, or soot). These pollutants are known to cause a range of serious health problems, from asthma attacks and cardiovascular disease to premature death. In the most recent edition of the report, more than 130 U.S. cities received failing grades for having dangerous levels of ozone and/or particle pollution. Among them, there are a few that might surprise you – like Fresno, California or Denver, Colorado. These grades reflect the number of days residents are exposed to unhealthy air, based on data collected from official EPA monitoring stations over a three-year period. Table of Contents A failing grade means that residents are regularly breathing air that exceeds federal health-based standards. This not only endangers those with pre-existing conditions like asthma, heart disease, or chronic obstructive pulmonary disease, but also affects children, pregnant people, and older adults — and ultimately, the health of entire communities. Troublingly, the State of the Air report reveals that air quality is worsening in many parts of the country, especially as climate change intensifies heat waves, wildfires, and droughts — all of which contribute to higher levels of ozone and particle pollution. Cities in the West, Midwest, and South saw particularly sharp declines in air quality, with more days classified as unhealthy for sensitive groups and the general population alike. The data signals an urgent need for bold, coordinated action to curb pollution and protect public health. America’s Most Polluted Cities and the Communities According to the latest report, the following cities rank among the worst in the U.S. for combined ozone and particle pollution: Los Angeles, CA – Highest ozone pollution and among the worst for PM2.5. Bakersfield, CA – High levels of both ozone and particle pollution. Fresno-Madera-Hanford, CA – Similar to Bakersfield, driven by agriculture and wildfires. Visalia, CA – Significant PM2.5 due to valley geography and regional fires. Phoenix, AZ – Worsening ozone pollution and extreme heat-related air quality issues. Denver, CO – Wildfire smoke and increasing ozone levels from urban sprawl. Houston, TX – High ozone days tied to petrochemical industry and vehicle traffic. Chicago, IL – Fails for both pollutants; industrial and transportation-related. Indianapolis, IN – Notable for worsening ozone levels. Las Vegas, NV – Rising ozone and PM2.5 due to heat, sprawl, and nearby wildfires. How Cities Are Evaluated for Air Quality Behind every letter grade in the State of the Air report is a detailed assessment of local pollution levels and public health risk. The grading system helps translate complex air quality data into an easy-to-understand snapshot of how clean — or hazardous — the air is in a given area. These grades offer crucial insight into which communities are breathing unhealthy air and why. The Grading System Cities and counties receive separate grades for: Ozone pollution Short-term particle pollution (daily spikes of PM2.5) Annual particle pollution (long-term average levels of PM2.5) Each category is assigned a letter grade from A to F, based on the number of days the air pollution exceeded federal health-based standards, as set by the Environmental Protection Agency (EPA). GradeMeaningAThe air met EPA standards every day — excellent air quality.B–CFew unhealthy days recorded — generally acceptable, but some concern.DAir pollution exceeded EPA standards on several days — health risks present.FAir pollution exceeded EPA standards many times — unhealthy and dangerous. What Ozone Grades Measure Ozone, or smog, forms when sunlight reacts with emissions from cars, factories, and other sources. It’s especially harmful on hot days. Grades are based on: The number of high ozone days (as defined by the EPA) The severity of the pollution on those days Ozone pollution particularly affects children, the elderly, and people with lung conditions like asthma or COPD. What Particle Pollution Grades Measure PM2.5 refers to microscopic particles — such as smoke, dust, or soot — that can penetrate deep into the lungs and bloodstream. The report gives two separate grades: Short-term PM2.5: Based on daily spikes in pollution, often from wildfires, industrial releases, or heavy traffic Annual PM2.5: Based on the average level of fine particles across an entire year High particle pollution is linked to heart disease, strokes, lung cancer, and premature death. What a Failing Grade Means for Public Health A failing grade doesn’t just reflect poor environmental conditions — it signals a public health crisis. Communities that consistently receive Fs are experiencing dangerous levels of pollution that can shorten lifespans, increase hospital visits, and worsen chronic diseases. These grades are particularly alarming when they appear in areas with large populations of vulnerable residents, such as children, seniors, and people living near pollution sources. By grading cities, the State of the Air report not only informs the public, but also helps hold policymakers and polluters accountable — encouraging urgent action to clean up the air and protect the health of every resident. Failing Cities by Region Air pollution isn’t evenly distributed across the United States — it varies by geography, industry, infrastructure, and climate. While the State of the Air report identifies more than a hundred U.S. cities with failing grades, the underlying causes and consequences differ widely depending on the region. In the Northeast, industrial activity and dense urban development contribute to persistent smog, while in the West, worsening wildfires and heat intensify fine particulate matter. The South and Midwest face their own distinct challenges, including sprawling development, vehicle congestion, and a legacy of environmental injustice. The following case studies highlight some of the most heavily impacted cities across the country, providing a closer look at why air quality is deteriorating and who is most affected. Northeast Philadelphia, Pennsylvania Pollution Grade and Types: Philadelphia received an “F” for ozone pollution and moderate rankings for year-round particle pollution. Primary Causes of Poor Air Quality: Heavy traffic congestion, aging diesel truck fleets, and industrial activity in surrounding counties. Health Impacts: Rising asthma rates among children and increased hospital visits due to respiratory distress. Disproportionate Impact: North and West Philadelphia, which have large Black and Hispanic populations, see higher exposure to pollution due to proximity to highways and industrial corridors. Solutions: Local organizations are advocating for clean port technology and more stringent emissions regulations for transit vehicles. Midwest Chicago, Illinois Pollution Grade and Types: Chicago received failing grades for both ozone and particle pollution. Primary Causes of Poor Air Quality: Emissions from vehicles, especially diesel trucks serving industrial zones and rail yards, are major contributors. Lake Michigan also traps smog during the summer. Health Impacts: High prevalence of asthma in neighborhoods like Little Village and South Lawndale. Disproportionate Impact: Communities of color on the South and West Sides face chronic exposure due to industrial zoning and proximity to freight infrastructure. Solutions: Mayor-led efforts to electrify public transit and restrict new polluting facilities in overburdened areas. South Nashville, Tennessee Pollution Grade and Types: Nashville received an “F” for high ozone days and worsening particle pollution levels. Primary Causes of Poor Air Quality: Rapid urban expansion and increased car traffic, particularly along interstates like I-40 and I-65. Health Impacts: Rising rates of asthma and respiratory illness, especially among young children Disproportionate Impact: Predominantly Black and Hispanic neighborhoods adjacent to major highways experience elevated pollution levels. Solutions: The city’s “Choose How You Move” transit initiative aims to reduce reliance on personal vehicles and promote cleaner alternatives. Houston, Texas Pollution Grade and Types: Houston consistently fails for ozone pollution and ranks among the worst for particle pollution spikes. Primary Causes of Poor Air Quality: Oil and gas refineries, high vehicle use, and extreme summer temperatures intensify smog formation. Health Impacts: Increased hospitalizations for asthma, especially during ozone alert days. Disproportionate Impact: Latino and Black communities near refineries and shipping channels bear the brunt of chronic air pollution. Solutions: Community groups push for stronger EPA enforcement and transition away from fossil fuel infrastructure. West Los Angeles, California Pollution Grade and Types: Los Angeles tops the list for worst ozone pollution and ranks high for both daily and annual particle pollution. Primary Causes of Poor Air Quality: Heavy car traffic, port emissions, and increasing wildfire smoke have worsened smog in the region. Health Impacts: Elevated asthma rates in children and premature deaths from cardiovascular and lung disease. Disproportionate Impact: Low-income neighborhoods in East LA and South Central, which border freeways and industrial zones, face persistent exposure. Solutions: Aggressive clean car standards and port electrification efforts are underway. Phoenix, Arizona Pollution Grade and Types: Phoenix received failing grades for both ozone and particulate pollution. Primary Causes of Poor Air Quality: Sprawling development, vehicle use, and desert dust combined with high temperatures create dangerous air conditions. Health Impacts: Heat-related illnesses are exacerbated by poor air, especially among outdoor workers. Disproportionate Impact: Latinx communities in South Phoenix face higher exposure due to highway-adjacent housing and limited green space. Solutions: City initiatives to expand electric bus fleets and tree planting programs in heat islands. Despite regional differences, one theme is clear across every city featured: air pollution is not just an environmental issue — it’s a public health emergency and a matter of racial and economic justice. In nearly every case, the highest levels of pollution are found in communities of color and low-income neighborhoods, where systemic factors have placed residents closer to highways, industrial sites, or other major pollution sources. As cities begin to invest in cleaner transportation, stricter emissions rules, and renewable energy, targeted action must ensure that the communities most burdened by dirty air are the first to benefit. 2025 Nationwide Pollution Trends The American Lung Association’s State of the Air report paints a troubling picture of air quality in the United States, with widespread and worsening pollution trends driven by a combination of climate change, urbanization, and fossil fuel reliance. Two key pollutants—ozone (smog) and fine particulate matter (PM2.5)—are driving failing air quality grades across the country, threatening the health of nearly 120 million Americans. Continued Ozone Pollution Rise in 2025 Ozone levels are increasing in many parts of the country, largely due to rising temperatures linked to climate change. Hot, sunny conditions create the ideal environment for ozone to form when pollutants from vehicles, power plants, and industrial facilities react in the atmosphere. As heatwaves become more frequent and prolonged, ozone pollution is becoming more persistent and severe—especially in major metropolitan areas in the South and Southwest. PM2.5 Pollution and the Western Wildfire Crisis Fine particulate matter, or PM2.5, remains a critical concern nationwide, but it has become especially dangerous in the Western U.S., where wildfire smoke is now a leading contributor. States like California, Oregon, and Washington have seen dramatic spikes in particle pollution during fire seasons, which are growing longer and more intense due to drought, heat, and forest mismanagement. These particles can penetrate deep into the lungs and bloodstream, causing or worsening respiratory and cardiovascular conditions. Regional Patterns West PM2.5 pollution has worsened significantly due to wildfire smoke. Cities like Los Angeles, Bakersfield, and Fresno rank among the worst in the nation for particle pollution and ozone. South Urban growth and vehicular traffic drive high ozone levels in cities like Houston, Dallas, and Nashville. Warm, sunny weather exacerbates smog formation. Midwest Industrial activity, freight transport, and seasonal weather patterns contribute to both ozone and particulate pollution in cities like Chicago and Indianapolis Northeast Aging infrastructure and dense urban areas drive moderate-to-high ozone pollution, with Philadelphia and New York City consistently earning failing grades These rankings underscore a national public health emergency, as air pollution intensifies across both traditionally polluted regions and areas once considered relatively clean. Without urgent policy changes and investment in clean energy, climate mitigation, and transit alternatives, more American cities may soon join this list. Air Quality Through An Environmental Justice Lens Air pollution in the United States is not experienced equally. Across the country, communities of color and low-income populations are disproportionately exposed to dirty air — a result of long-standing policies and structural decisions that have placed the heaviest environmental burdens on the most marginalized groups. The State of the Air report repeatedly emphasizes that the people breathing the worst air often have the fewest resources to respond to its health consequences. A National Pattern of Disparity According to the American Lung Association, more than 70 million people of color live in counties that received at least one failing grade for ozone or particle pollution — over 60% more than the number of white people living in similarly polluted areas. This disparity is no accident. It reflects decades of discriminatory practices in housing, infrastructure planning, and industrial development. Proximity to Pollution Sources In many cities, neighborhoods with large Black, Latino, and immigrant populations are located near highways, freight corridors, power plants, and industrial zones — major sources of air pollution. North Nashville, TN: Predominantly Black neighborhoods are flanked by Interstate 40, where car and truck traffic releases harmful exhaust. This same highway was built through the heart of the community during the urban renewal era, splitting it physically and economically. South Bronx, NY: A heavily Latino and Black neighborhood bordered by expressways and industrial facilities, the South Bronx has some of the highest asthma hospitalization rates in the country due to diesel truck traffic and power plant emissions. West and South Fresno, CA: These areas are home to many Latino and Black residents and are surrounded by agriculture, freight corridors, and oil refineries — contributing to dangerously high levels of both ozone and PM2.5. South Chicago, IL: Formerly redlined communities now face elevated pollution from steel plants, diesel freight movement, and warehouse development, all while lacking green space and public health investment. Structural Roots of Inequity Many of these disparities trace back to racist zoning laws, redlining, and exclusionary infrastructure projects that intentionally placed polluting facilities in or near communities of color. Meanwhile, wealthier, whiter neighborhoods have historically wielded more political power to resist such developments or demand stricter enforcement. Compounding the problem, these communities often lack adequate healthcare access, green space, and investment in clean transit — making it harder to avoid or recover from pollution-related health problems. As climate change worsens air quality, these communities are expected to bear the brunt of future harm unless environmental justice becomes a central part of air quality policy. Addressing air pollution equitably means not only reducing emissions overall, but prioritizing cleanup in the communities most harmed by decades of neglect and pollution. How People in High-Pollution Cities Can Protect Themselves For millions of Americans living in cities with failing air quality grades, the risks are immediate and serious — especially for children, older adults, and people with underlying health conditions like asthma, COPD, or heart disease. While systemic solutions are needed to address the root causes of pollution, individuals and families can take steps to reduce their exposure and protect their health. Monitor Air Quality Daily Stay informed about air conditions in your area: Use websites and apps like AirNow.gov or the EPA’s AQI app to check real-time air quality. Pay close attention to “Code Orange,” “Red,” or worse air quality alerts, which signal unhealthy conditions. Plan outdoor activities for early morning or late evening when ozone levels tend to be lower. Limit Exposure During High-Pollution Days Stay indoors when air quality is poor, especially during midday when ozone levels peak. Use indoor air purifiers with HEPA filters to reduce particulate matter inside your home. Keep windows and doors closed and set HVAC systems to “recirculate” during pollution spikes or wildfire events. Protect Your Lungs When Outdoors If you must be outside during high-PM or ozone events, wear an N95 mask to filter out fine particles — particularly important during wildfire smoke episodes. Avoid high-traffic areas or long periods of strenuous activity near roads and industrial sites. Walk or bike along low-traffic routes or greenways, where possible. Create a Clean Air Safe Room Choose one room in your home (ideally without many windows) where you can use an air purifier and seal off outside air during poor AQI events, such as wildfires or smog waves. Top 3 Recommended Air Purifiers Coway Airmega 400S Best for: Large rooms, wildfire smoke, and year-round use in cities like Los Angeles, Fresno, and Phoenix Why it’s recommended: This smart purifier combines a dual HEPA and activated carbon filtration system, making it ideal for areas with high PM2.5 and ozone-related pollutants. It covers up to 1,560 sq. ft. and features real-time air quality monitoring. Best for: Wildfire smoke, urban pollution, large living spaces Buy on Amazon Levoit Core 300S Best for: Budget-conscious residents in small to medium rooms (ideal for renters in cities like Chicago, Houston, and Philadelphia) Why it’s recommended: Compact but powerful, this affordable air purifier uses a 3-stage filtration system (pre-filter, HEPA, carbon) and is especially effective at removing fine particles like soot and dust — a major concern in high-traffic and industrial areas. Best for: Bedrooms, apartments, people managing asthma or allergies Buy on Amazon IQAir HealthPro Plus Best for: People with respiratory issues, immunocompromised individuals, and those in cities with year-round pollution like Bakersfield, Denver, and Indianapolis Why it’s recommended: A medical-grade option that goes beyond standard HEPA, using HyperHEPA filtration to trap ultrafine particles down to 0.003 microns — smaller than most viruses. Excellent for homes near highways or industrial zones. Best for: Serious air quality needs, including chronic lung or heart conditions Buy on Amazon Manage Chronic Health Conditions If you or your child has a respiratory condition, make sure medications are current and that action plans (e.g., asthma action plans) are in place and accessible. Consult with your doctor about adjusting treatment if you’re experiencing more symptoms during high-pollution periods. Be Prepared for Wildfire Smoke In Western states, where wildfires now drive much of the PM2.5 pollution, prepare for smoke season as you would for extreme weather: Stockpile N95 masks and air filters. Keep an emergency plan for power outages (especially if using electric purifiers or needing electricity for medical devices). Join Community Action Connect with local environmental or public health groups working on clean air initiatives. Advocate for better air monitoring in your neighborhood, particularly if you live near a highway, refinery, or industrial site. While no one can avoid polluted air entirely, being proactive — and prepared — can reduce harmful exposure and help communities build resilience as they push for long-term solutions. Key Takeaway The State of the Air report is more than a set of statistics — it’s a wake-up call. From urban centers in the South and West to industrial corridors in the Midwest and Northeast, millions of America ns are breathing unhealthy air every day. The health consequences are real, and the burdens fall hardest on communities of color and low-income neighborhoods already facing systemic challenges. But this crisis is not inevitable. With bold federal action, local leadership, and community advocacy, we can clear the air — and protect the health of generations to come. Clean air is not a luxury; it’s a basic human right. Learn More About Air Purifiers for Pollution More on Air Quality Can Indoor Air Pollution Affect Physical Fitness and Exercise? Does Pollution Make Allergies Worse? Gas Stoves and Indoor Air Quality How to Test Your Home’s Air Quality Do Air Quality Monitors Work? 5 Tips to Find the Right One HEPA Air Purifier Tech to Address Air Quality Issues Content on this site is for reference and information purposes only. Do not rely solely on this content, as it is not a substitute for advice from a licensed healthcare professional. AirPurifiers.com assumes no liability for inaccuracies. Consult with your doctor before beginning any medications or programs.
