Study Shows 440 Excess Deaths Attributable to 2025 Fires
A Boston University study, published in JAMA on August 6, 2025, estimates that 440 excess deaths in Los Angeles County were attributable to the January 2025 wildfires between January 5 and February 1, 2025 - while only 30-31 direct fatalities were officially reported.
This study underscores that direct fatality counts (e.g., from burns or immediate trauma) significantly undercount the total mortality burden of climate-related disasters.
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A Boston University study, published in JAMA on August 6, 2025, estimates that 440 excess deaths in Los Angeles County were attributable to the January 2025 wildfires between January 5 and February 1, 2025 - while only 30-31 direct fatalities were officially reported.
This study underscores that direct fatality counts (e.g., from burns or immediate trauma) significantly undercount the total mortality burden of climate-related disasters.
Drivers of Excess Mortality: The surge in deaths is attributed to indirect effects of the fires, which severely affected air quality (smoke exposure) and disrupted healthcare access for vulnerable populations.
Findings: The findings suggest the actual mortality burden of 440 attributable deaths, resulting from poor air quality, health care disruptions, and stress, was over 14 times higher than the 31 reported direct deaths. Thus, the percentage mortality increase was approximately 7 % above the expected deaths (5,931) in this time period, resulting in total observed deaths of 6,371. (Estimated Excess Deaths: 440 (95% CI, 131 to 744).
Methodology: Researchers from Boston University School of Public Health and the University of Helsinki used an interrupted-time-series design to evaluate county-level, all-cause mortality. The model compared observed deaths to expected deaths based on data from 2018, 2019, and 2024 (excluding 2020-2023 due to COVID-19 anomalies).
Study Limitations: Data used were provisional and subject to revision.
The study may not capture all deaths occurring outside the defined 4-week window.
Sensitivity analyses suggest some deaths may represent a "selection effect" (mortality brought forward by a few months).
Link to Boston University Post 2025 LA Fires Study: (Excess Deaths Attributable to the Los Angeles Wildfires from January 5 to February 1, 2025 | Research, Methods, Statistics | JAMA | JAMA Network, published August, 6, 2025).
Also published on the NIH: National Library of Medicine