The effect of future ambient air pollution on human premature mortality to 2100 using output from the ACCMIP model ensemble

Abstract

Ambient air pollution from ground-level ozone and fine particulate matter (PM2.5) is associated with premature mortality. Future concentrations of these air pollutants will be driven by natural and anthropogenic emissions and by climate change. Using anthropogenic and biomass burning emissions projected in the four Representative Concentration Pathway scenarios (RCPs), the ACCMIP ensemble of chemistry-climate models simulated future concentrations of ozone and PM2.5 at selected decades between 2000 and 2100. We use output from the ACCMIP ensemble, together with projections of future population and baseline mortality rates, to quantify the human premature mortality impacts of future ambient air pollution. Future air pollution-related premature mortality in 2030, 2050 and 2100 is estimated for each scenario and for each model using a health impact function based on changes in concentrations of ozone and PM2.5 relative to 2000 and projected future population and baseline mortality rates. Additionally, the global mortality burden of ozone and PM2.5 in 2000 and each future period is estimated relative to 1850 concentrations, using present-day and future population and baseline mortality rates. The change in future ozone concentrations relative to 2000 is associated with excess global premature mortality in some scenarios/periods, particularly in RCP8.5 in 2100 (316 thousand deaths/year), likely driven by the large increase in methane emissions and by the net effect of climate change projected in this scenario, but it leads to considerable avoided premature mortality for the three other RCPs. However, the global mortality burden of ozone markedly increases from 382,000 (121,000 to 728,000) deaths/year in 2000 to between 1.09 and 2.36 million deaths/year in 2100, across RCPs, mostly due to the effect of increases in population and baseline mortality rates. PM2.5 concentrations decrease relative to 2000 in all scenarios, due to projected reductions in emissions, and are associated with avoided premature mortality, particularly in 2100: between −2.39 and −1.31 million deaths/year for the four RCPs. The global mortality burden of PM2.5 is estimated to decrease from 1.70 (1.30 to 2.10) million deaths/year in 2000 to between 0.95 and 1.55 million deaths/year in 2100 for the four RCPs, due to the combined effect of decreases in PM2.5 concentrations and changes in population and baseline mortality rates. Trends in future air pollution-related mortality vary regionally across scenarios, reflecting assumptions for economic growth and air pollution control specific to each RCP and region. Mortality estimates differ among chemistry-climate models due to differences in simulated pollutant concentrations, which is the greatest contributor to overall mortality uncertainty for most cases assessed here, supporting the use of model ensembles to characterize uncertainty. Increases in exposed population and baseline mortality rates of respiratory diseases magnify the impact on premature mortality of changes in future air pollutant concen...

HTAP2 multi-model estimates of premature human mortality due to intercontinental transport of air pollution and emission sectors

“…While some models reported hourly O 3 metrics, others only reported daily or monthly O 3 . We include these models by first calculating the ratio of the 6-month average of daily 1 h maximum O 3 to the annual average of O 3 in individual grid cells, for models reporting hourly O 3 , and then applying that ratio to the annual average of ozone for those models that only report daily or monthly O 3 , following Silva et al (2013Silva et al ( , 2016b. For PM 2.5 , we calculate the annual average PM 2.5 concentration in each cell using the monthly total PM 2.5 concentrations reported by each model ("mmrpm2p5").…”

HTAP2 multi-model estimates of premature human mortality due to intercontinental transport of air pollution

“…We include these models by first calculating the ratio of the 6-month average of 216 daily 1-h maximum O3 to the annual average of O3 in individual grid cells, for models 217 reporting hourly O3, and then applying that ratio to the annual average of ozone for 218 those models that only report daily or monthly O3, following Silva et al (2013;2016b for 187 countries from the GBD 2010 mortality dataset (IHME, 2013). The population 276 and baseline mortality per age group were regridded to the 0.5 ο ×0.5 ο grid (Table S2 277 and Fig.…”

Long-term trends in the PM<sub>2.5</sub>- and O<sub>3</sub>-related mortality burdens in the United States under emission reductions from 1990 to 2010

“…Previous health impact assessments have used national baseline mortality rates (Cohen et al, 2017;Silva et al, 2016aSilva et al, , 2016b, but baseline mortality rates can vary strongly within individual counties (supporting Figure S5; Dwyer-Lindgren et al, 2016). We performed sensitivity analyses by applying the national average baseline mortality rates for each disease to every county in the mortality burden calculations.…”

“…For PM2.5, is calculated using the integrated exposure-response (IER) model (Burnett et al, 2014), which has been extensively used by recent studies, including Liu et al (2017), Silva et al (2016a, b), Wang et al (2017), and World Health 10 Organization (2016). The is calculated as a function of PM2.5 concentration following Eq.…”