Mortality risk attributable to wildfire-related PM2·5 pollution : a global time series study in 749 locations

Abstract

BACKGROUND : Many regions of the world are now facing more frequent and unprecedentedly large wildfires. However, the association between wildfire-related PM2·5 and mortality has not been well characterised. We aimed to comprehensively assess the association between short-term exposure to wildfire-related PM2·5 and mortality across various regions of the world. METHODS : For this time series study, data on daily counts of deaths for all causes, cardiovascular causes, and respiratory causes were collected from 749 cities in 43 countries and regions during 2000–16. Daily concentrations of wildfire-related PM2·5 were estimated using the three-dimensional chemical transport model GEOS-Chem at a 0·25° × 0·25° resolution. The association between wildfire-related PM2·5 exposure and mortality was examined using a quasi-Poisson time series model in each city considering both the current-day and lag effects, and the effect estimates were then pooled using a random-effects meta-analysis. Based on these pooled effect estimates, the population attributable fraction and relative risk (RR) of annual mortality due to acute wildfire-related PM2·5 exposure was calculated. FINDINGS : 65·6 million all-cause deaths, 15·1 million cardiovascular deaths, and 6·8 million respiratory deaths were included in our analyses. The pooled RRs of mortality associated with each 10 μg/m³ increase in the 3-day moving average (lag 0–2 days) of wildfire-related PM2·5 exposure were 1·019 (95% CI 1·016–1·022) for all-cause mortality, 1·017 (1·012–1·021) for cardiovascular mortality, and 1·019 (1·013–1·025) for respiratory mortality. Overall, 0·62% (95% CI 0·48–0·75) of all-cause deaths, 0·55% (0·43–0·67) of cardiovascular deaths, and 0·64% (0·50–0·78) of respiratory deaths were annually attributable to the acute impacts of wildfire-related PM2·5 exposure during the study period. INTERPRETATION : Short-term exposure to wildfire-related PM2·5 was associated with increased risk of mortality. Urgent action is needed to reduce health risks from the increasing wildfires.The Australian Research Council, the Australian National Health and Medical Research Council, a Career Development Fellowship of the Australian National Health and Medical Research Council, an Early Career Fellowship of the Australian National Health and Medical Research Council, the National Natural Science Foundation of China, the Czech Science Foundation, the Spanish Ministry of Economy, Industry and Competitiveness, the National Key Research and Development Program of China, EU’s Horizon 2020 Project Exhaustion, the Ministry of Science and Technology of Taiwan, the Medical Research Council UK, the Natural Environment Research Council UK, a fellowship of the Fundação para a Ciência e a Tecnologia, the Science and Technology Commission of Shanghai Municipality and the National Institute of Environmental Health Sciences-funded HERCULES Center.http://www.thelancet.com/planetary-healtham2022Geography, Geoinformatics and Meteorolog