Research Report 195 describes a study led by Dr. Armistead (Ted) G. Russell at the Georgia Institute of Technology in Atlanta, Georgia, as part of HEI’s Accountability Research Program. Accountability research evaluates whether regulatory and other actions aimed at improving air quality have resulted in actual decreases in air pollutant concentrations and improvements in public health. Dr. Russell and colleagues at Georgia Tech and Emory University examined the extent to which national and state regulations targeting power plants and mobile sources in the Atlanta area were effective in reducing pollutant emissions, improving air quality, and ultimately reducing cardiorespiratory emergency department visits. To do this, they compared actual daily emissions, air quality, and emergency departments in the period from 1999 to 2013 to projections of what might have happened in the absence of regulations. This is one of few accountability studies to follow changes of individual regulations on emissions all the way through health outcomes, using scenarios with and without regulation.