Researchers estimate global mortality from smoke

Wildfire smoke affected areas

Wildfire Today recently reported on a study that linked wildfire smoke with increased physician visits. Now other researchers claim they can estimate the number of people that die each year as a result of breathing smoke particulates, PM2.5. Their principal estimate for the world-wide average mortality attributable to smoke exposure for 1997-2006 is 339,000 deaths annually. According to the researchers, the mortality could be substantially reduced by curtailing burning of tropical rainforests, which rarely burn naturally.

Wildfire smoke affected areas
Spatial locations of the 14 terrestrial Global Fire Emission Database (GFED) regions used in global fire emissions modeling. The warm colors (red, orange, pink) represent the fire-affected area. (from the study)

HERE is a link to “supplemental material” which explains the researchers’ methodology. Below, is the abstract from the paper.


Background: Forest, grass and peat fires release approximately two petagrams of carbon into the atmosphere each year, influencing weather, climate, and air quality.

Objective: To estimate the annual global mortality attributable to landscape fire smoke (LFS).

Methods: Daily and annual exposure to particulate matter < 2.5 micrometers (PM2.5) from fire emissions was estimated globally for 1997-2006 by combining outputs from a chemical transport model with satellite-based observations of aerosol optical depth. In World Health Organization (WHO) subregions classified as sporadically impacted, the daily burden of mortality was estimated using previously published concentration-response coefficients for the association between short-term elevations in PM2.5 from LFS (contrasted with 0 μg/m3 from LFS) and all-cause mortality. In subregions classified as chronically impacted, the annual burden of mortality was estimated using the American Cancer Society study coefficient for the association between long-term PM2.5 exposure and all-cause mortality. The annual average PM2.5 estimates were contrasted with theoretical minimum (counterfactual) concentrations in each chronically impacted subregion. Sensitivity of mortality estimates to different exposure assessments, counterfactual estimates, and concentration-response functions was evaluated. Strong La Niña and El Niño years were compared to assess the influence of inter-annual climatic variability.

Results: Our principal estimate for the average mortality attributable to LFS exposure was 339,000 deaths annually. In sensitivity analyses the interquartile range of all tested estimates was 260,000 to 600,000. The regions most affected were Sub-Saharan Africa (157,000) and Southeast Asia (110,000). Estimated annual mortality during La Niña was 262,000 compared with 532,000 during El Niño.

Conclusions: Fire emissions are an important contributor to global mortality. Adverse health outcomes associated with LFS could be substantially reduced by curtailing burning of tropical rainforests, which rarely burn naturally. The large estimated influence of El Niño suggests a relationship between climate and the burden of mortality attributable to LFS.


Citation: Johnston FH, Henderson SB, Chen Y, Randerson JT, Marlier M, DeFries RS, et al. 2012. Estimated Global Mortality Attributable to Smoke from Landscape Fires. Environ Health Perspect.

Thanks go out to Dick

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Author: Bill Gabbert

After working full time in wildland fire for 33 years, he continues to learn, and strives to be a Student of Fire.