Carbon pollution standards that reduce carbon dioxide emissions from existing power plants can also cut emissions of other power plant pollutants and byproducts that have negative human and environmental health impacts locally and regionally. These air pollutants and byproducts include sulfur oxides, nitrogen oxides, mercury, soot, and smog. Therefore, policies intended to address climate change by reducing carbon dioxide emissions that also decrease emissions of additional air pollutants can have important human and environmental health co-benefits.

This study, led by Syracuse and Harvard universities, used existing estimates of energy sector emissions for the year 2020 for a Reference Case and three alternative policy scenarios to quantify the amount and spatial distribution of resulting changes in emissions, the release of sulfur, nitrogen, mercury, soot, and smog into the air. Each policy scenario reflects different carbon standard designs with varying stringency and flexibility. The three scenarios bound a wide range of possible policy alternatives.