Maryland Gov. Larry Hogan (R) announced yesterday that his state will sue the U.S. Environmental Protection Agency over its decision not to require 36 coal-fired power plant units in five upwind states to run their existing air pollution controls more frequently. In July, Maryland officials indicated they were considering a lawsuit, after the EPA rejected a request to broaden the roster of states in the region responsible for helping address cross-state pollution. EPA allowed itself a six-month extension to act on the petition, which expired in mid July. Maryland estimates that, on some days, up to 70% of its ozone problem originates from emissions in upwind states.