Millions of Americans suffer from the harmful effects of ground-level ozone pollution, resulting in more time spent in emergency rooms, and additional sick days. These health impacts not only involve suffering; they also constitute a significant drag on the U.S. economy. Climate change has the potential to increase ozone pollution—and its health and economic burdens—both now and in the future, creating "climate penalty" on ozone. This report demonstrates how higher temperatures could increase ozone pollution above current levels, explores the resulting expected health consequences in 2020 and 2050, and the anticipated economic costs of these health impacts in 2020.