Amid rollbacks of the Clean Power Plan and other environmental regulations at the federal level, several U.S. states, cities, and towns have resolved to take matters into their own hands and implement policies to promote renewable energy and reduce greenhouse gas emissions. One popular approach, now in effect in 29 states and the District of Columbia, is to set Renewable Portfolio Standards (RPS), which require electricity suppliers to source a designated percentage of electricity from available renewable-power generating technologies.

Boosting levels of renewable electric power not only helps mitigate global climate change, but also reduces local air pollution. Quantifying the extent to which this approach improves air quality could help legislators better assess the pros and cons of implementing policies such as RPS. Toward that end, a research team at MIT has developed a new modeling framework that combines economic and air-pollution models to assess the projected subnational impacts of RPS and carbon pricing on air quality and human health, as well as on the economy and on climate change. In a study focused on the U.S. Rust Belt, their assessment showed that the financial benefits associated with air quality improvements from these policies would more than pay for the cost of implementing them. The results appear in the journal Environmental Research Letters.

“This research helps us better understand how clean-energy policies now under consideration at the subnational level might impact local air quality and economic growth,” says the study’s lead author Emil Dimanchev, a senior research associate at MIT’s Center for Energy and Environmental Policy Research, former research assistant at the MIT Joint Program on the Science and Policy of Global Change, and a 2018 graduate of the MIT Technology and Policy Program.

The MIT research team’s results for the Rust Belt are consistent with previous studies, which found that the health co-benefits of climate policy (including RPS and other instruments) tend to exceed policy costs.

“This work shows that there are real, immediate benefits to people’s health in states that take the lead on clean energy,” says MIT Associate Professor Noelle Selin, who led the study and holds a joint appointment in the Department of Earth, Atmospheric and Planetary Sciences and Institute for Data, Systems and Society. “Policymakers should take these impacts into account as they consider modifying these standards.”