Promised health gains from the decline of coal-fired electricity are being undone by pollution caused by burning other combustion fuels like gas and wood pellets, new research from Harvard scientists finds. The study, published Wednesday in Environmental Research Letters, found stationary sources, like power plants, buildings, and industrial boilers, killed at least 47,000 people in the U.S. in 2017, and gas-fired pollution killed more people than coal in at least 19 states plus DC. “If you swap out one combustion fuel for another, that’s not a pathway toward a healthy energy system,” Harvard research scientist and the paper’s lead author Jonathan Buonocore told HuffPost. “This is showing that even with the transition from coal to gas, there are remaining impacts.” The research, which was supported by RMI, found particulate pollution (technically known as PM2.5) from biomass pollution “essentially replaced” averted sulfur dioxide emissions from coal and oil combustion.

So-called natural gas, which is mostly methane, was touted as a “bridge fuel” from coal to renewable energy, but a new report from Energy Innovation released earlier this week says new wind and solar capacity cost less to build than 80% of U.S. coal plants cost to keep running. (Harvard: HuffPost, E&E $, Fast Company, Chicago Tribune; Energy Innovation: Bloomberg $, E&E $)