Wildfire smoke impacts respiratory health more than fine particles from other sources: observational evidence from Southern California

TLDR

Wildfires are increasingly frequent and destructive, and their fine particulate matter (PM₂.₅) is known to harm human health, yet current air‑quality regulations assume all PM₂.₅ is equally toxic. The study aims to determine whether wildfire‑derived PM₂.₅ is more or less harmful than PM₂.₅ from other sources. The authors isolated wildfire‑specific PM₂.₅ by applying statistical approaches and exposure definitions to distinguish it from ambient PM₂.₅. They found that a 10 µg m⁻³ increase in wildfire‑specific PM₂.₅ raised respiratory hospitalizations by 1.3–10 %, compared with 0.67–1.3 % for non‑wildfire PM₂.₅, underscoring the need for source‑specific air‑quality policies.

Abstract

Abstract Wildfires are becoming more frequent and destructive in a changing climate. Fine particulate matter, PM 2.5 , in wildfire smoke adversely impacts human health. Recent toxicological studies suggest that wildfire particulate matter may be more toxic than equal doses of ambient PM 2.5 . Air quality regulations however assume that the toxicity of PM 2.5 does not vary across different sources of emission. Assessing whether PM 2.5 from wildfires is more or less harmful than PM 2.5 from other sources is a pressing public health concern. Here, we isolate the wildfire-specific PM 2.5 using a series of statistical approaches and exposure definitions. We found increases in respiratory hospitalizations ranging from 1.3 to up to 10% with a 10 μg m −3 increase in wildfire-specific PM 2.5 , compared to 0.67 to 1.3% associated with non-wildfire PM 2.5 . Our conclusions point to the need for air quality policies to consider the variability in PM 2.5 impacts on human health according to the sources of emission.