A new Cedars-Sinai ER study looking at emergency room data found sharp increases in heart attacks, pulmonary illness, and “general illness” in the 90 days after the January 2025 fires began in Los Angeles County, even though total ER visits did not rise compared to prior years.
The research, published in the Journal of the American College of Cardiology, analyzed visits to the Cedars-Sinai Emergency Department from Jan. 7 through April 7, 2025, then compared that period with the same calendar window in 2018 through 2024. Cedars-Sinai’s main campus is about 10 miles from Pacific Palisades and about 20 miles from Altadena, where the biggest fires ignited, the study authors noted.
The headline numbers were steep. Investigators reported a 118% increase in ER visits for general illness, a 46% increase in visits for heart attack, and a 24% increase in visits for pulmonary illness, compared with the average rates for those conditions during the same period over the prior seven years.
“Wildfires that spread into urban areas have proven to be extremely dangerous because of how quickly they move and what they burn and release into the environment,” said Dr. Susan Cheng, vice chair of Research Affairs in Cedars-Sinai’s Department of Cardiology at the Smidt Heart Institute, and the study’s senior author. Cheng said the findings suggest the Eaton and Pacific Palisades fires had an immediate effect on people’s health.
Cheng pointed to two likely drivers, fine particles in smoke that can enter the body and injure the heart and lungs, and stress tied to living through the fires, which can show up in a wide range of health problems.
The study also flagged something researchers said has not been previously reported after major wildfires: abnormal blood test results tied to general illness more than doubled during the 90-day period in 2025, compared with the same period in previous years.
“Abnormal blood test results could indicate that the body is responding to an external stressor such as toxins in the air,” said Dr. Joseph Ebinger, the study’s first author and an associate professor in Cedars-Sinai’s Department of Cardiology. Ebinger said the findings are a step toward understanding how the Eaton and Palisades fires may have affected residents, and that more research is needed to identify ways to reduce ongoing risks and protect people in future fire events.
Cedars-Sinai said the work is part of the larger LA Fire HEALTH Study, a multi-institution collaboration expected to track health impacts for the next 10 years. Partner institutions named in the project include the Harvard T.H. Chan School of Public Health, USC’s Keck School of Medicine, Stanford, UCLA, UC Davis, UC Irvine, the University of Texas at Austin, and Yale, among others.
Cedars-Sinai said the study was partially supported by the Spiegel Family Fund, the Smidt Heart Foundation, and the Erika J. Glazer Family Foundation.
