L.A. came out on top in the American Lung Association’s annual “State of the Air” Report, which was released on Wednesday. That’s not a good thing.
Each year for the past 26 years, the American Lung Association has released an annual report that analyzes data from official air quality monitors and comes up with a list of the most polluted cities in the U.S. And for 25 out of those 26 years, L.A. has come in first as the country’s smoggiest city. So it’s not like it’s a surprise. And with the wildfires in January, air quality has been on our minds even more than normal. But it’s still a bit confronting and concerning, to say the least.
The ALA measures air quality by two factors: ozone and fine particular matter (which is divided into year-round particle pollution and short-term particle pollution). And we, um, didn’t score great in any category.
For the purposes of the ranking, “L.A.” is actually the Greater Los Angeles area, which includes Los Angeles, Orange, Ventura, Riverside and San Bernardino counties. With that in mind, L.A. was No. 1 in ozone pollution, No. 5 in year-round particle pollution and No. 7 in short-term particle pollution. (We were No. 11 in short-term particle pollution at the start of the year, which would suggest that we rose in the ranks due to the copious amounts of wildfire smoke in January, but the 2025 report actually is pulled from air quality data from 2021 to 2023, so the wildfires’ effects wouldn’t be reflected yet.)
In addition, when breaking down the list by county, Southern California occupies the top three spots for ozone offenders: San Bernardino, Riverside and Los Angeles are the three worst counties, in that order.
Smog—a.k.a. ground-level ozone—is formed in the lower atmosphere when fossil fuels including gasoline, diesel, oil, natural gas and coal are burned, creating nitrogen oxides and volatile organic compounds that are then “cooked” in the sunlight to form ozone. And unsurprisingly, L.A.’s car culture is a prime culprit, as motor vehicles and gas stations are among the worst offenders. As is our warm weather—our climate might make us the envy of other cities, but high temperatures plus pollutants is a bad combination.
According to the report, L.A. residents are contending with an average of 153.7 days of unhealthy levels of ozone per year—that’s almost twice as many unhealthy air days as the second city on the list. And ozone poses a whole host of health risks, including lung irritation and inflammation. It also impacts the respiratory system both in the short and long terms, and can generally shorten lives.
What are the (other) smoggiest cities in the U.S.?
L.A. may be getting bad press as the smoggiest U.S. city, but let’s face it—we’re far from the only place dealing with unhealthy air. In fact, almost half of the country’s population lives with unhealthy amounts of air pollution—that’s almost 25 million more people breathing unhealthy air than there were last year, according to the report.
Besides L.A., when it comes to ozone, three other California cities make up the top five: Visalia is No. 2, Bakersfield-Delano No. 3, Phoenix (also notoriously hot) sneaks in at No. 4, and going back to California, Fresno-Hanford-Corcoran make up No. 5. Other big cities follow: Denver, Houston, San Diego (No. 8), Salt Lake City and Dallas round out the top 10.
What’s more, there are 27 counties that received failing grades for all three measures of pollution, including Los Angeles. California has the largest presence on that list, representing 14 of those 27 counties.
It’s not all bad news
Okay, being named the smoggiest city in the country isn’t great. But luckily we live in California, where we have a long history of investing in environmental improvements and clean air policies at the local and state levels. The ALA actually praised California, saying that even though the state faces “the most difficult air pollution challenges in the United States, California’s leadership has continued to reduce ozone and particle pollution in the state.”
And the good news is that it’s starting to make a difference: This year, 12 California metropolitan areas had their best reports ever in the history of the “State of the Air” series, and Los Angeles was one of the cities that achieved its best-ever report for at least one pollutant (year-round particle pollution).
Some more proof: Compared to when the “State of the Air” reports began, L.A. residents are actually exposed to an average of 77 fewer days of unhealthy ozone levels a year—that’s a nearly 40% improvement—than they were back in 2000.
So it’s not all doom and gloom. The ALA also provides some recommendations for action, including using your voice to help protect the Environmental Protection Agency, which is responsible for both monitoring and cleaning up air pollution and which is facing staff and funding cuts. The association also recommends checking daily air pollution forecasts at airnow.gov, making sure you’re prepared for wildfires and other disasters by visiting lung.org/disaster, and doing your part to reduce emissions at home and from your car.