On May 14, 2021, the U.S. Environmental Protection Agency (EPA) rescinded a rule issued during the Trump administration that changed how EPA calculated and presented the costs and benefits of rules under the Clean Air Act (CAA). Advanced on the ground of providing greater transparency, the rule had required EPA to determine the benefits that a new regulation provided directly, while separately valuing the “co-benefits” that would accrue by reducing other pollutants not covered by the new regulation. Industry had argued that EPA regulations should be based solely on the value of reducing the emissions it was authorized to regulate — while opponents argued the rule would ignore obvious benefits and justify weakening regulation.

(more…)