A year after the LA fires, the first hard emergency-department numbers are in
Cedars-Sinai counted a 118% rise in general-illness visits and a 46% rise in heart attack visits over the 90 days after the fires started. Abnormal blood results more than doubled.
One year ago today the Palisades and Eaton fires began. The property loss was counted almost immediately. The health cost has taken until now to acquire a number, and the first substantial one comes from an emergency department.
Researchers at Cedars-Sinai analysed emergency department visits from 7 January to 7 April 2025 — the 90 days from the start of the fires — and compared them with the same calendar window in each of the years 2018 through 2024 [s1]. The analysis was published in the Journal of the American College of Cardiology in December [s1].
Against that seven-year baseline they found a 118 per cent increase in visits for general illness, a 46 per cent increase in visits for heart attack, and a 24 per cent increase in visits for pulmonary illness [s1].
The finding that was not expected
The result the investigators flagged as new concerns laboratory values rather than diagnoses.
Abnormal blood test results related to general illness more than doubled across the 90-day window compared with the same period in previous years [s1]. The release describes this as a finding not previously reported after major wildfires [s1].
Joseph Ebinger, associate professor in the Department of Cardiology and the study's first author, said abnormal blood results could indicate that the body is responding to an external stressor such as toxins in the air [s1].
The importance of this is evidential rather than clinical. A rise in emergency visits after a disaster can be produced by anxiety, by displacement, by disrupted access to routine care, or by people seeking reassurance. A rise in objectively abnormal laboratory values is harder to explain that way. It points toward a measurable physiological disturbance rather than a behavioural one.
What the study cannot separate
The design is a before-and-after comparison at a single hospital. It establishes that these presentations rose; it does not isolate why.
Susan Cheng, vice chair of research affairs in the Department of Cardiology and senior author, named both candidate mechanisms directly: fine particles released by wildfires can enter the body and cause injury, particularly to the heart and lungs, and stress related to the fires may also contribute to a broad range of health issues [s1].
Those two pathways are not separable in this dataset. Everyone in the region was exposed to both the smoke and the emergency at the same time.
Two further limits are worth stating. The study counted visits at one institution, and the Cedars-Sinai emergency department sits roughly 10 miles from Pacific Palisades and 20 miles from Altadena, where the largest fires began [s2] — near enough to catch the plume, far enough that it is not the closest facility to either burn zone. And notably, total emergency visits overall showed no significant difference [s2]. The composition of who came in changed; the volume did not.
That last detail cuts against the simplest alternative explanation. If a general surge of worried people had driven the result, total visits would have risen too.
Where this sits in a larger effort
The analysis is one output of the LA Fire HEALTH Study, a ten-year multi-institution collaboration involving Harvard, UCLA, USC and Cedars-Sinai, designed to establish which pollutants were present, at what levels and where, and to assess effects on respiratory, neurological, cardiovascular, reproductive and immune systems [s3].
Its published work so far covers a wider range than smoke inhalation. A Nature Medicine paper in June 2025 examined immune system responses to fire smoke exposure [s3]. A paper in Environmental Science & Technology the same month reported adverse birth outcomes linked to heat stress and wildfire smoke during pregnancy [s3]. A JAMA Internal Medicine piece discussed long-term implications and drew a comparison to military burn pit exposure [s3]. On 2 January, ES&T Letters published measurements of volatile organic compounds indoors and outdoors [s3].
The burn pit comparison is the one that explains the ten-year timeframe. Urban wildfire smoke is not forest smoke. It contains the combustion products of houses, vehicles and their contents, and the health questions it raises are chronic-exposure questions that a 90-day window cannot answer.
What to watch
The emergency department data establish an acute signal. The unresolved questions are whether the cardiovascular excess persisted beyond three months, whether the abnormal laboratory values normalised, and what the indoor contamination measurements imply for people who returned to standing but smoke-exposed homes. All three are within the scope of the ongoing study [s3], and none has been answered yet.
Sources
- [s1] Cedars-Sinai reports heart attacks, general illness spiked after LA fires. Cedars-Sinai, 17 December 2025. https://www.cedars-sinai.org/newsroom/cedars-sinai-reports-heart-attacks-general-illness-spiked-after-la-fires/
- [s2] Cedars-Sinai reports heart attacks, general illness spiked after LA fires. EurekAlert (AAAS), 17 December 2025. https://www.eurekalert.org/news-releases/1110060
- [s3] Publications. LA Fire HEALTH Study, accessed 2 January 2026. https://lafirehealth.org/publications/
Sources
- Cedars-Sinai reports heart attacks, general illness spiked after LA fires — Cedars-Sinai , December 17, 2025
- Cedars-Sinai reports heart attacks, general illness spiked after LA fires — EurekAlert (AAAS) , December 17, 2025
- Publications — LA Fire HEALTH Study — LA Fire HEALTH Study , January 2, 2026
More on
Amazon smoke and forest loss now carry a death count in Brazil's own records
Fine particulate exposure in seven Amazonian capitals was tied to about 5,472 circulatory and 2,621 respiratory deaths over six years. A separate analysis finds cardiac mortality rising with forest loss.
Winter air pollution studies mostly ignore the viruses circulating at the same time
Two February papers put respiratory virus activity into the models. One finds pollution effects amplified at peak influenza; the other finds them attenuated when rhinovirus is high.
Three-quarters of US pregnancies since 2012 involved some wildfire smoke exposure
A 34-million-birth analysis maps how far smoke travels from the fires that make it. A companion review is blunt that what that exposure does, beyond the lungs, is still unsettled.
Only five studies qualified for a review of wildfire smoke and children's lungs
A November systematic review screened 120 publications and found five eligible papers, all from the US and Canada. All pointed the same way; none could be pooled with the others.