Los Angeles Grapples with Severe Air Pollution, Ranking Among World's Most Polluted Cities

Los Angeles is facing a significant environmental challenge, with recent data placing it among the most polluted cities globally. A tweet from user "BK 🇺🇸" on September 17, 2025, highlighted the gravity of the situation, stating, "> This is a big problem @MayorOfLA and @CAgovernor." This social media post underscores growing public concern over the persistent air quality issues impacting the region.

According to an IQAir report issued on September 15, 2025, Los Angeles experienced "poor air quality conditions" due to a combination of urban emissions, regional vehicle traffic, and atmospheric stagnation. The report noted particularly high concentrations of nitrogen dioxide (NO2) and carbon monoxide (CO), with the city ranking 15th among the most polluted major cities worldwide on that Monday morning. Local meteorological conditions, including calm winds and a strong thermal inversion, were cited as exacerbating factors, trapping emissions near the surface and limiting dispersion.

This recent air quality crisis follows a year marked by significant environmental challenges for California. Earlier in 2025, devastating wildfires, such as the Palisades and Eaton fires in January, caused widespread destruction and prompted severe air quality warnings due to smoke blanketing the region. Studies, including one published in ACS' Environmental Science & Technology Letters in August 2025, have examined the extensive air quality impacts from these earlier wildfires.

Both Los Angeles Mayor Karen Bass and California Governor Gavin Newsom have faced scrutiny regarding their handling of environmental and public health crises throughout the year. Governor Newsom's administration has actively engaged in efforts to protect the state's clean air policies, with the Governor announcing in May 2025 that California would legally challenge any attempts to undermine its clean vehicles program. Mayor Bass, who was out of the country during the initial January wildfires, later issued an executive order to streamline rebuilding efforts and mitigate future hazards.

Despite these measures, the ongoing air pollution in September 2025 indicates a persistent and complex problem for California's most populous city. The combination of urban pollution and the lingering effects or recurring threat of wildfires continues to pose significant health risks, particularly for vulnerable populations, and remains a critical issue for both city and state leadership.