Los Angeles has once again been labeled the smoggiest city in the United States, according to the American Lung Association’s latest “State of the Air” report, which was released on Wednesday.
This marks the 25th consecutive year that L.A. has held this notorious distinction, even as the number of unhealthy ozone days has plummeted nearly 40% since the year 2000.
While the report highlights some improvements in air quality metrics, it also shows that L.A. remains the seventh-most polluted city in the nation when it comes to particle pollution.
California is home to five out of the ten cities with the highest levels of ozone pollution and also five of the worst cities for particle pollution, according to the annual report.
Cities like Visalia, Bakersfield, Fresno, and San Diego have made the list for the worst ozone pollution, while for particle pollution, Bakersfield, Visalia, Fresno, L.A., and Sacramento rank among the top ten most polluted cities.
The concerns about air quality come amid recent announcements from the Environmental Protection Agency (EPA) regarding potential rollbacks of critical environmental regulations, which experts fear could reverse the progress made over the past decades in California.
Mary D. Nichols, a UCLA law professor and former chair of the California Air Resources Board, expressed apprehension during a news conference, stating, “Nobody wants to go back to the kinds of skies that triggered our clean air laws in the first place.
The current administration’s push to relax rules that protect public health is alarming, as it threatens to undermine the substantial gains achieved so far.
Nichols warned that dismantling the EPA would result in an increase in health issues among the population, particularly in children suffering from asthma, as well as increased premature deaths associated with poor air quality.
The “State of the Air” report primarily focuses on two types of pollution: ozone pollution, which is largely influenced by emissions from vehicles, and particle pollution, driven mainly by drought conditions and wildfires.
Alarmingly, the report found that over 34.3 million Californians reside in communities with at least one failing air quality grade, and 22.9 million live in areas that receive failing marks in three air quality categories.
Los Angeles’ longstanding smog issue is primarily due to the extensive use of automobiles since their mass adoption.
The concentration of millions of vehicles and the resulting emissions contribute significantly to smog formation, which is exacerbated by the region’s sunny climate and geographic barriers that trap pollutants.
State and local authorities have imposed strict regulations in an effort to curb emissions from cars and industrial sources.
Legislative measures such as Senate Bill 32 in 2014 and Assembly Bill 398 in 2017 have introduced stringent limits on greenhouse gas emissions and implemented a cap-and-trade system.
While the introduction of electric vehicles and improved engine technology has resulted in notable pollution reductions, transportation remains the predominant source of pollution in California’s urban centers.
Heavy-duty trucks, cargo ships, and trains significantly contribute to the region’s overall pollution levels.
Despite the challenges, California cities including Los Angeles have recorded their best results to date concerning ozone or particle pollution, according to Mariela Ruacho, a senior clean air advocacy manager at the American Lung Association.
Fresno, in particular, succeeded in achieving its lowest number of ozone days, particle days, and annual particle levels since the data was first recorded two decades ago.
Meanwhile, Bakersfield earned the unfortunate title of having the least healthy air in the country, ranking as the most particle-polluted city both for short-term and annual levels.
To further progress in air quality, the American Lung Association called for phasing out agricultural burning and ensuring sustained investments in cleaning up heavy-duty trucks and providing incentives for off-road agricultural equipment.
While California has seen significant air quality improvements since the first “State of the Air” report, concerns remain regarding the impact of climate change and new legislation.
One bill, SB 712, aims to fully exempt collector cars that are at least 35 model years old from smog check requirements, a move that could potentially hinder the advancements made in air quality over the years.
Ruacho stated, “Unhealthy air is inequitable and unaffordable.
To prevent costly health emergencies, California must intensify its investments in wildfire risk reduction, promote zero-emission transportation and energy sources, and align transportation funding with pollution reduction initiatives.”
image source from：https://www.latimes.com/california/story/2025-04-23/despite-progress-los-angeles-is-nations-smoggiest-city-for-25th-time-in-26-years
