The EPI shows that air pollution is the top leading threat to public health. Its purpose isn’t to scare the public; it has the potential to truly impact policy. “As the world community pursues new sustainable development goals, policymakers need to know who is leading and who is lagging on energy and environmental challenges,” said Daniel C. Esty, director of the Yale Center for Environmental Law & Policy and the Hillhouse Professor at Yale University, in a press release.