In science news around the world, the United States requires companies to cut their production and use of hydrofluorocarbons, a potent greenhouse gas used in refrigeration, as part of the country9s most significant climate legislation in 10 years. With President Donald Trump9s term nearing its end, the U.S. Environmental Protection Agency unveils its final rule restricting the scientific studies that can be used in writing regulations affecting public health—a move the agency says will improve transparency but critics say will weaken its ability to use the best science. The Massachusetts Institute of Technology9s troubled Media Lab gets a new director. And U.S. regulators allow two makers of COVID-19 vaccines authorized for emergency use to offer the shots to people who had received a placebo in ongoing efficacy trials.