Associations Between Simulated Future Changes in Climate, Air Quality, and Human Health
Fann, N., Chris Nolte, M. Sarofim, J. Martinich, AND N. Nassikas. Associations Between Simulated Future Changes in Climate, Air Quality, and Human Health. JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION. JAMA, Meudon, France, 4(1):e2032064, (2021).
Many studies have established that climate change affects the rates of formation of ozone and PM2.5, two air pollutants with known deleterious impacts on human health. However, the magnitude of the air pollution-attributable health effects due to climate change have not been well quantified, particularly the dependence on air pollutant emissions. In this study, two climate model scenarios are used to investigate climate change impacts on air quality over the 21st century, using both 2011 emissions and a 2040 emissions projection reflecting certain emissions controls, and the resulting health impacts are quantified.
Importance Future changes in climate are likely to adversely affect human health by affecting concentrations of particulate matter sized less than 2.5 μm (PM2.5) and ozone (O3) in many areas. However, the degree to which these outcomes may be mitigated by reducing air pollutant emissions is not well understood. Objective To model the associations between future changes in climate, air quality, and human health for 2 climate models and under 2 air pollutant emission scenarios. Design, Setting, and Participants This modeling study simulated meteorological conditions over the coterminous continental US during a 1995 to 2005 baseline and over the 21st century (2025-2100) by dynamically downscaling representations of a high warming scenario from the Community Earth System Model (CESM) and the Coupled Model version 3 (CM3) global climate models. Using a chemical transport model, PM2.5 and O3 concentrations were simulated under a 2011 air pollutant emission data set and a 2040 projection. The changes in PM2.5 and O3-attributable deaths associated with climate change among the US census-projected population were estimated for 2030, 2050, 2075, and 2095 for each of 2 emission inventories and climate models. Data were analyzed from June 2018 to June 2020. Main Outcomes and Measures The main outcomes were simulated change in summer season means of the maximum daily 8-hour mean O3, annual mean PM2.5, population-weighted exposure, and the number of avoided or incurred deaths associated with these pollutants. Results are reported for 2030, 2050, 2075, and 2095, compared with 2000, for 2 climate models and 2 air pollutant emissions data sets. Results The projected increased maximum daily temperatures through 2095 were up to 7.6 °C for the CESM model and 11.8 °C for the CM3 model. Under each climate model scenario by 2095, compared with 2000, an estimated additional 21 000 (95% CI, 14 000-28 000) PM2.5-attributable deaths and 4100 (95% CI, 2200-6000) O3-attributable deaths were projected to occur. These projections decreased to an estimated 15 000 (95% CI, 10 000-20 000) PM2.5-attributable deaths and 640 (95% CI, 340-940) O3-attributable deaths when simulated using a future emission inventory that accounted for reduced anthropogenic emissions. Conclusions and Relevance These findings suggest that reducing future air pollutant emissions could also reduce the climate-driven increase in deaths associated with air pollution by hundreds to thousands.