An analysis by Cedars-Sinai has found a significant increase in heart attacks, lung complications, and general illness following the January 2025 wildfires in Los Angeles. The study was published in JACC and led by Susan Cheng, MD, MPH, vice chair of Research Affairs in the Department of Cardiology at the Smidt Heart Institute.
“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 Cheng. “Our research suggests the Eaton and Pacific Palisades fires had an immediate effect on people’s health.”
Cedars-Sinai’s Emergency Department, located about 10 miles from Pacific Palisades and 20 miles from Altadena—where the largest fires began—collected data on emergency visits for 90 days after the fires started on January 7, 2025. This data was compared with emergency department visits during the same period from 2018 to 2024.
While total emergency visits did not show a significant change, there were notable increases in specific conditions: a 118% rise in visits for general illness, a 46% increase for heart attacks, and a 24% rise for pulmonary illnesses compared to averages over the previous seven years.
“Fine particles released by wildfires can enter the body and cause injury, particularly to the heart and lungs,” Cheng said. “Stress related to the fires may also contribute to a broad range of health issues.”
The study also reported that abnormal blood test results linked to general illness more than doubled during this period—a finding not previously documented after major wildfires.
“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 Cardiology at Cedars-Sinai 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.”
The research is part of the LA Fire HEALTH Study—a collaborative effort among Cedars-Sinai; Harvard T.H. Chan School of Public Health; Keck School of Medicine at USC; Stanford University; UCLA; UC Davis; UC Irvine; University of Texas at Austin; and Yale University—to assess long-term impacts over ten years.
Additional authors from Cedars-Sinai 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; Alan C. Kwan, MD. Brian L. Claggett from Brigham and Women’s Hospital also contributed.
Funding sources included the Spiegel Family Fund, Smidt Heart Foundation, and Erika J. Glazer Family Foundation.
Cedars-Sinai Medical Center is based in Los Angeles and was founded in 1902. It operates as both a treatment facility—with over 50,000 patient admissions reported in its most recent annual report—and as a training hospital with pediatric services (https://www.cedars-sinai.org/about.html).
Cedars-Sinai Health Sciences University continues research efforts while educating future leaders across medical fields.
