Wildfire Smoke Linked to Heart Issues & Health Spikes in LA Study

The aftermath of the Palisades and Eaton wildfires that swept through Los Angeles County in January 2025 brought a surge in heart attack cases and unusual blood test results, according to a new study published in the Journal of the American College of Cardiology. The research highlights the often-overlooked public health consequences of wildfires, extending beyond immediate burns and respiratory issues to include a significant increase in cardiovascular events and systemic physiological stress.

Unexpected Spike in Cardiac Events

In the 90 days following the start of the fires, Cedars-Sinai Medical Center in Los Angeles experienced a 46% increase in emergency room visits for heart attacks compared to the same period over the previous seven years. Visits related to respiratory illnesses also rose, increasing by 24%. Perhaps more strikingly, unusual blood test results – indicating a broader disruption of bodily systems – more than doubled, climbing by 118%. This suggests the fires’ impact wasn’t limited to those with pre-existing conditions or obvious respiratory distress. The Los Angeles Times reported on these findings in December 2025, detailing the unusual patterns observed by Cedars-Sinai clinicians.

Researchers, led by Dr. Joseph Ebinger, a cardiologist at Cedars-Sinai, believe the unique composition of materials burned in these fires contributed to the unusual health effects. Unlike typical wildfires that primarily consume vegetation, the Palisades and Eaton fires burned through a mix of trees, brush and a substantial amount of man-made materials – cars, batteries, plastics, and electronics. This created a “toxic stew” of pollutants, according to the study, exposing a large population to a novel and potentially dangerous combination of smoke constituents. Dr. Ebinger noted that Los Angeles has experienced wildfires before, but the scale and composition of these fires were exceptional.

Beyond Emergency Visits: Systemic Physiological Stress

The study didn’t find a significant overall increase in total emergency department visits, suggesting people weren’t necessarily flooding the hospital with complaints. Instead, the increase in cardiac events and respiratory issues was offset by a decrease in visits for mental health emergencies and chronic conditions. This suggests people may have been avoiding healthcare settings or that the fires prompted a shift in health-seeking behavior. However, the significant rise in abnormal blood test results points to a more widespread, systemic impact.

These unusual blood tests revealed a range of anomalies, including electrolyte imbalances, altered protein levels, and changes in kidney and liver function markers. Dr. Susan Cheng, director of public health research at Cedars-Sinai and senior author of the study, explained that these atypical results indicated a “kind of metabolic-biochemical stress on the body” affecting multiple organ systems. This suggests the smoke exposure triggered a cascade of physiological responses, leading to a diverse range of symptoms in different individuals.

Longer-Term Effects and Comparative Research

What sets this research apart is the duration of observed effects. Most studies examining the health impacts of wildfire smoke find elevated rates of respiratory and cardiovascular issues for about a week after exposure. However, the Cedars-Sinai study tracked elevated rates of heart attacks and abnormal blood tests for a full three months. This longer timeframe aligns with findings from other research, such as a study by Joan Casey, an environmental epidemiologist at the University of Washington, which found a 27% increase in respiratory outpatient visits among Kaiser Permanente members in Southern California living within 12.4 miles of the burn areas in the week following the fires. Cedars-Sinai’s newsroom details the study’s findings, and implications.

Casey suggests the severity of the Los Angeles fires – encompassing both the smoke and the widespread evacuations and resulting stress on the population – may explain the prolonged effects. The fires were a “highly stressful event,” she noted, and the impacts may have lingered longer than in previous wildfire-related studies.

Documented Fatalities and Potential Underestimation

While 31 deaths were directly attributed to injuries sustained during the fires, researchers believe the true death toll is likely much higher. They hypothesize that deaths resulting from pre-existing conditions exacerbated by smoke exposure haven’t been fully accounted for. A research letter published earlier in 2025 in the Journal of the American Medical Association estimated 440 excess deaths in Los Angeles County between January 5th and February 1st, accounting for deaths related to air pollution exposure and disruptions in healthcare access due to closures and evacuations. A team from Stanford University estimated that exposure to wildfire smoke, specifically, contributed to 14 additional deaths.

The Unique Risks of Wildfire Smoke

Wildfires are a major source of fine particulate matter pollution (PM2.5), particles 2.5 micrometers in diameter or smaller. These tiny particles can bypass the body’s natural defenses and penetrate deep into the lungs and even the bloodstream, crossing the blood-brain barrier. Compared to other sources of particulate matter, wildfire smoke contains a higher proportion of these ultra-fine particles, making it particularly hazardous. Casey explained to the Times that these particles are small enough to enter the brain after inhalation. Wildfire smoke has been linked to a range of health problems, including dementia, cancer, and cardiovascular failure. Healthcare Brew reported on how Los Angeles hospitals responded to the wildfires, including Cedars-Sinai postponing elective surgeries and closing clinics.

Over the past decade, the increasing frequency and intensity of wildfires in the Western United States have reversed years of progress made under the Clean Air Act and other pollution control measures. The health consequences of these fires are becoming increasingly apparent, demanding a more comprehensive understanding of the long-term effects of smoke exposure and the development of effective mitigation strategies.

Looking Ahead: Surveillance and Research

Ongoing surveillance of emergency department visits and public health data will be crucial for tracking the long-term health impacts of the Los Angeles fires and future wildfire events. Further research is needed to identify vulnerable populations, understand the specific components of wildfire smoke that pose the greatest health risks, and develop targeted interventions to protect public health. This includes refining air quality monitoring systems, improving public communication about wildfire risks, and exploring strategies to reduce smoke exposure, such as providing high-efficiency particulate air (HEPA) filters to at-risk communities. The findings from Cedars-Sinai underscore the necessitate for a proactive and comprehensive approach to wildfire preparedness and public health protection.