Future fire-PM_2.5 mortality varies depending on climate and socioeconomic changes

Fire emits hazardous air pollutants, the most dominant of which is fine particulate matter of diameter <= 2.5 mu m (PM2.5). PM2.5 is a great concern due to its adverse effects on public health. Previous studies have examined the health burden from fire-related PM2.5 for the historical period; however, future global mortality associated with fire-PM2.5, particularly under the coexisting impacts of climate and socioeconomic changes, is yet to be projected. Here, we estimated the mortality associated to fire-PM2.5 (fire-PM2.5 mortality) for the present period (2010s) and then projected the mortality for the 2050s and 2090s under 10 scenarios created by combining two Representative Concentration Pathways (RCP2.6 or 6.0) with five Shared Socioeconomic Pathways (SSP1-5). We used the Li-Park fire model in combination with a chemical transport model and health risk assessment to calculate fire-PM2.5 mortality. For the present period, the estimated fire-PM2.5 mortality was 135 180 (105 403-163 738), which is 1.7 deaths per 100 000 population globally. When countries were grouped by income, the fire-PM2.5 mortality rate was the highest in the high-income country group and lowest in the lowest-income country group. For the 2050s and 2090s, the fire-PM2.5 mortality rate was projected to decrease under most scenarios because of decreases in fire emissions and baseline mortality rate. However, a scenario of high population growth and low technical development (SSP3) together with severe global warming (RCP6.0) would lead to an increase in the fire-PM2.5 mortality rate in the 2090s, particularly in the highest-income countries, due to increased fire under drier and warmer weather conditions. Stratification of countries by gross domestic product indicated the need for adaptation efforts in the highest-income countries to avoid future increases of mortality associated with fire-PM2.5.