People across the United States are becoming more concerned about air quality because millions are being affected by pollutants. Through the American Lung Association’s State of the Air 2025 and information from IQAir, serious trends in PM2.5 levels were noted, due mostly to wildfires, car pollution, factories, and changes brought by climate events such as drought and heat. While some cities have made positive changes, numerous others are having difficulties with ongoing unhealthy air. Here are ten cities or regions currently experiencing the worst air pollution in the nation.
1. Bakersfield, California
As one of America’s most polluted cities for many years, Bakersfield continues to place number one in 2025. The Central Valley of California houses the city, where farming, oil use, and geographic features combine to keep pollutants local. In addition to emissions from industry, the area deals with serious levels of ozone and wildfire smoke pollution. Bakersfield has some of the biggest PM2.5 problems in the country, which can put people’s lungs at risk.
2. Fresno, California
To the north, in Fresno, challenges related to the environment in the Central Valley are also felt. The air in the city suffers from agricultural dust as well as emissions from vehicles and more prevalent wildfire smoke. Frequent spikes of PM2.5 levels both in summer and winter mean that Fresno’s residents are exposed to unhealthy air almost all year. Frequent warnings from health experts are given, mainly for kids and the elderly, because they can become sick more easily from pollution.
3. Visalia, California
Similar to other cities in the Central Valley, Visalia, found between Fresno and Bakersfield, struggles with air pollution. Lately, there have been some of the worst short-term days of particulate air pollution in recent history. Activity from more wildfires nearby is making the situation worse, and long-lasting drought reduces the cleaning effects of rain on the air. The haze that regularly covers the city reduces sight and can harm people’s health.
4. Los Angeles, California
For many years, smoke pollution in Los Angeles was well known, but even with clean-air changes, the city still has poor air quality. High levels of air pollution in the basin are caused by busy traffic, ports, and factories, and the nearby mountains keep pollutants from escaping. Large amounts of ozone are a challenge, and smoke from forest fires often gets into the city. During the summer, many people report unhealthy AQI levels for those sensitive to air pollution.
5. San Francisco, California
For years, San Francisco’s ocean breezes helped keep its air pollution low, but in recent years, more wildfires have greatly reduced the city’s air quality. Fires in Northern California put so much smoke into the air that PM2.5 reaches levels much higher than what is safe in the city for days. At the beginning of 2025, the city of San Francisco had weeks of high pollution, which prompted officials to issue warnings and keep schools closed for some time. Outdoor workers and people without homes are the most seriously affected.
6. Detroit, Michigan
The city’s past in manufacturing has continued to influence the air around Detroit. While upgrades and emission decreases have already happened, air pollution remains high close to industrial parks and highway areas. Some neighborhoods show rates of asthma and heart disease that are higher than those seen elsewhere. Additional heating emissions in winter make the problem ongoing and harmful to many people.
7. Cleveland, Ohio
Just as in Detroit, Cleveland deals with the aftermath of pollution from its steel and industrial plants. Lake Erie is close to the city, and when it’s cold, weather patterns can cause pollutants to become trapped over the town. The figures from 2025 reveal that Cleveland has some of the highest concentrations of PM2.5 in the Midwest. Many parts of the city’s east side have seen a lot of air quality alerts and a rise in hospital visits for breathing problems.
8. Houston, Texas
Houston, where oil is processed and shipped, is still among the most polluted cities in the south. Because of its heavy industry, the city puts out high amounts of VOCs and sulfur dioxide, which cause smog and can harm the lungs. Don’t forget about the added complication of port and highway traffic as well. In 2025, IQAir identified sections of the Houston metro area as having some of the worst air quality in the U.S., mostly during summertime.
9. Fairbanks, Alaska
Even though Fairbanks is not close to major pollution areas, it still has serious problems with its air quality. When it is winter, the city faces inversions that hold smoke and car emissions hugging the ground. Because most homes burn wood for heat, the level of PM2.5 goes up to harmful amounts. During 2025, Fairbanks experienced several weeks of air quality that went well over the 150 AQI limit, which is unsafe for health. Because the region is so isolated, it is harder to move the stagnant air.
10. Eugene, Oregon
Wildfire-related pollution has been a challenge in Eugene recently, despite its reputation for environmentally friendly living. Because of its location among forests, the city often faces smoke from both fires around it and farther away. Eugene had more than 20 days last year where air quality was unhealthy, most caused by a record-setting fire season in the Pacific Northwest. As a result of wood-burning stoves and more cars, the city has ended up on a list of areas with less healthy air quality.
Air Quality and Public Health
Air quality in some regions of the U.S. is worsening, as these ten cities show. Although air monitoring and strict emission rules have advanced, climate change and wildfires are increasing the level of air particles. Almost 156 million people in the United States, according to the American Lung Association, are exposed to pollution that can lead to lung disease, heart trouble, and an early death.
Conclusion: A Call for Urgent Action
The 2025 data on air pollution in the United States is a wake-up call. While some cities have made strides in reducing ozone and smog, many others are now facing new and intensifying threats due to wildfires, industrial activity, and changing climate patterns. The top 10 most polluted cities in the country show that no region is immune, from urban manufacturing centers to remote Alaskan towns. It is vital for policymakers, communities, and individuals to push for stronger environmental protections and clean energy solutions to safeguard the air we breathe.
