A group of doctors at UPMC pushed the Pittsburgh hospital system to do things like reduce waste and switch chemicals. Now the effort is gaining momentum. We’ll also talk with climatologist Michael E. Mann about his new book that looks back millions of years into Earth’s history to help us survive the climate crisis. Plus, environmentalists trawl local waterways in search of little plastic pellets that could harm wildlife.

We have news about a potential lawsuit over plastic pollution in the Ohio River, EPA’s rejection of parts of U.S. Steel’s air quality permit for the Clairton Coke Works, and climate activists in Harrisburg.