The impact of climate change and emissions control on future ozone levels: Implications for human health.

Overwhelming evidence has shown that, from the Industrial Revolution to the present, human activities influence ground-level ozone (O) concentrations. Past studies demonstrate links between O exposure and health. However, knowledge gaps remain in our understanding concerning the impacts of climate change mitigation policies on O concentrations and health. Using a hybrid downscaling approach, we evaluated the separate impact of climate change and emission control policies on O levels and associated excess mortality in the US in the 2050s under two Representative Concentration Pathways (RCPs). We show that, by the 2050s, under RCP4.5, increased O levels due to combined climate change and emission control policies, could contribute to an increase of approximately 50 premature deaths annually nationwide in the US. The biggest impact, however, is seen under RCP8.5, where rises in O concentrations are expected to result in over 2,200 additional premature deaths annually. The largest increases in O are seen in RCP8.5 in the Northeast, the Southeast, the Central, and the West regions of the US. Additionally, when O increases are examined by climate change and emissions contributions separately, the benefits of emissions mitigation efforts may significantly outweigh the effects of climate change mitigation policies on O-related mortality.