The Potential Impact of a Clean Energy Society on Air Quality

The emissions from fossil fuel use not only affect climate but also affects air pollution both directly (emitting primary particles) and indirectly (emitting precursors for formation of ozone [O-3] and particulates). Effects on ozone and particulates (especially PM2.5) are of major concern because of their adverse health effects on human and other life on Earth. Although alternative energy use is increasing, the impacts are not yet large enough to reduce the poor air quality resulting from extensive use of fossil fuels and resulting emissions in much of the world. A more definite energy transformation is needed to reduce these health impacts. Here, we examine the possibility of a midcentury future, where, because of its influence on climate, fossil fuel use has been extensively reduced in much of the world, and replaced by nonpolluting forms of energy. Analyses of the clean energy future globally and in five regions across the world, including 29 megacities, show that air quality with respect to ozone and particulate pollution improves significantly. When compared to the high-emission future under the clean energy scenario, population weighted ozone, and particulate matter exposure are reduced by >40% and 50%, respectively. The number air quality noncompliance events, defined by exceedance days and air quality index (AQI), improved considerably under the clean energy scenario. Annually, exceedance days are reduced to 0.7% +/- 1.7% for ozone pollution and 7.4% +/- 17.8% for particulate pollution under the clean energy scenario. AQI always stayed above the "very unhealthy category" and are improved significantly for the "unhealthy category" in all regions. Overall major hotspots experienced significantly cleaner air under the clean energy scenario, emphasizing the significance of transforming energy production, and moving away from conventional use of fossil fuels, on air quality and human health.