Climate change is already causing widespread harm to the health of all people living in the United States, with extreme heat making workers less productive and toxic air contributing to 64,000 deaths in a single year. In a new brief on climate change and health in the U.S. published Nov. 13, University of Washington and Harvard University researchers say it is still possible to prevent some health effects and mitigate others, and that aggressive action on climate is also action to protect health.