44% of Americans breathe dangerously polluted air. In California, it's 82%

Key Points:

• Greater Los Angeles remains the most ozone-polluted metro area in the U.S., with an average of 159.2 unhealthy ozone days annually, according to the American Lung Association’s 2026 State of the Air report. The region also ranks seventh worst nationally for both annual and short-term particle pollution.
• Los Angeles County received failing grades in ozone, short-term particle pollution, and annual particle pollution, with Riverside and San Bernardino counties also failing all three measures. Orange County received failing grades for ozone and annual particle pollution, but a C for short-term particle pollution.
• The report attributes Southern California's pollution primarily to transportation emissions, refineries, and local sources, exacerbated by climate and geographic factors that push pollution inland, especially impacting the Inland Empire. Despite some progress in reducing annual particle pollution, ozone pollution worsened, keeping Los Angeles ranked worst for smog in 26 of 27 years.
• Nationally, 44% of Americans live in areas with unhealthy ozone or particle pollution, including 46% of children under 18. California counties dominate the lists of worst pollution days, with eight of the 15 worst ozone counties and nine of the 15 worst year-round particle pollution counties located in the state.
• The ALA warned that recent federal rollbacks on clean air regulations threaten California’s efforts to improve air quality, potentially causing thousands of deaths and significant health and economic impacts by 2050. The report emphasized the particular vulnerability of children to air pollution’s harmful effects on lung development and respiratory health.