Interactions of Climate Change, Air Pollution, and Human Health

I review literature on the impacts of climate change on air quality and human health, with a focus on articles published from 2013 on ozone and airborne particles. Selected previous literature is discussed where relevant in tracing the origins of our current knowledge.

Climate and weather have strong influences on the spatial and temporal distribution of air pollution concentrations. Emissions of ozone and PM_2.5 precursors increase at higher ambient temperatures. The reactions that form ozone occur faster with greater sunlight and higher temperatures. Weather systems influence the movement and dispersion of air pollutants in the atmosphere through the action of winds, vertical mixing, and precipitation, all of which are likely to alter in a changing climate. Recent studies indicate that, holding anthropogenic air pollution emissions constant, ozone concentrations in populated regions will tend to increase in future climate scenarios. For the USA, the climate impact on ozone is most consistently seen in north-central and north-eastern states, with the potential for many thousands of additional ozone-related deaths. The sensitivity of anthropogenic PM_2.5 to climate is more variable across studies and regions, owing to the varied nature of PM constituents, as well as to less complete characterization of PM reaction chemistry in available atmospheric models. However, PM emitted by wildland fires is likely to become an increasing health risk in many parts of the world as climate continues to change. The complex interactions between climate change and air quality imply that future policies to mitigate these twin challenges will benefit from greater coordination. Assessing the health implications of alternative policy approaches towards climate and pollution mitigation will be a critical area of future work.