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# Wildfire smoke PM2.5 in US counties: excess deaths peak three years after exposure
- URL: https://www.coios.me/wildfire-smoke-pm2-5-in-us-counties-excess-deaths-peak/
- Published: 2026-10-17T09:19:33.000Z
- Updated: 2026-10-17T09:44:33.000Z
- Description: Monthly county-level wildfire PM2.5 and mortality data gave 1.7 million smoke-associated deaths over 2011-2023, about ten times conventional estimates.
- Author: Daniel Ryan
- Tags: Tomorrow's world, A changing climate, United States, #preprint, #contradicts, #item, #source-2026-10, #score-85

The study examined mortality following episodic wildfire smoke exposure across United States counties. Monthly county-level wildfire PM2.5 and death counts were used. Episodic exposure contrasts served to deconvolve overlapping responses and recover an impulse-response function. Excess mortality peaked about three years after an exposure pulse and subsided by five years. The authors estimate 1.7 million smoke-associated deaths during 2011-2023, about ten times the estimate from long-term ambient PM2.5 relative risks. Circulatory and respiratory causes contributed comparably, and responses were larger in adults aged 65 and over. The design is ecological, so exposure is assigned at county rather than individual level.

*Why it is interesting: Deaths continue to accumulate for three years after exposure, giving a far larger burden than conventional ambient PM2.5 relative risks.*

Source

[medRxiv, 16 October 2026](https://doi.org/10.64898/2026.10.15.26365428?ref=coios.me)

Paper

Wildfire smoke leaves a large five-year imprint on mortality in the United States

Authors

Zhang W, Su H, Ni R, Tao S, Lelieveld J, Cheng Y

DOI

10.64898/2026.10.15.26365428

Type

Preprint

Design

County-month panel of US wildfire PM2.5 and mortality, 2011-2023, deconvolved impulse-response estimation of lagged excess deaths

Verdict

Contradicts prior evidence

Driver

[A changing climate](https://www.coios.me/d-climate/)