Cedars-Sinai reports heart attacks, general illness spiked after LA fires

Correction, December 16, 2025: An earlier version of this news release incorrectly stated investigators found a 218% increase in visits for general illness. The correct statistic, based on the study, is 118%. 

An unusually high number of people developed a heart attack, lung complication or general illness within 90 days after the start of the January 2025 fires in Los Angeles, a new study from Cedars-Sinai reports. 

“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 Susan Cheng, MD, MPH, director of Public Health Research at Cedars-Sinai and senior author of the study, published in JACC. “Our research suggests the Eaton and Pacific Palisades fires had an immediate effect on people’s health.”

The Cedars-Sinai Emergency Department is located on the academic medical center’s main campus, about 10 miles from Pacific Palisades and about 20 miles from Altadena, the locations where the largest LA fires ignited in January 2025. Investigators collected data on emergency department visits during the 90 days after the fires started, from Jan. 7 to April 7, 2025. They compared this data with emergency visit data collected during the same calendar period in the years 2018 through 2024. 

Although there wasn’t a significant difference in total emergency department visits during the first 90 days following the start of the wildfires in 2025 as compared with other years, there was a drastic increase in emergency department visits for certain conditions. Investigators found a 118% increase in visits for general illness, 46% increase in the number of visits for heart attack, and a 24% increase in visits for pulmonary illness when compared to the average rate of these conditions diagnosed during the same time window in the past seven years. 

“Fine particles released by wildfires can enter the body and cause injury, particularly to the heart and lungs,” said Cheng, who is also the Erika J. Glazer Chair in Cardiovascular Health and Population Science in the Smidt Heart Institute at Cedars-Sinai. “Stress related to the fires may also contribute to a broad range of health issues.” 

The investigators found that abnormal blood test results related to general illness more than doubled in the 90-day period in 2025 as compared with that period in previous years. This is a finding not previously reported after major wildfires, according to the investigators.

“Abnormal blood test results could indicate that the body is responding to an external stressor such as toxins in the air,” said Joseph Ebinger, MD, MS, associate professor in the Department of Cardiology and first author of the study. “This study is an important step toward understanding how the Eaton and Palisades fires may have affected Angelenos’ health. We need more research to determine what we can do to mitigate any remaining risks and protect people from fire harm in the future.” 

This study is part of the larger LA Fire HEALTH Study, a research collaboration that seeks to determine the health effects of the fires that ignited in January 2025 in L.A. County. Investigators with Cedars-Sinai; the Harvard T.H. Chan School of Public Health; the Keck School of Medicine of the University of Southern California (USC); Stanford University; UCLA; the University of California, Davis (UCD); the University of California, Irvine (UCI); the University of Texas at Austin; and Yale University plan to study the impacts of the fires for the next 10 years. 

Additional Cedars-Sinai authors include Tzu Yu Huang, MS; Sandy Joung, MSHS, MBA; Juliane Kwong, BS; Wasay Warsi, MS, BS; Nancy Sun, MPS; Jesse Navarrette, MPA; Patrick Botting, DHSc; Zaldy S. Tan, MD, MPH; and Alan C. Kwan, MD.

Other authors include Brian L. Claggett, PhD, of Brigham and Women’s Hospital in Boston.

Funding: This work was partially supported by the Spiegel Family Fund, the Smidt Heart Foundation, and the Erika J. Glazer Family Foundation. 

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