Massachusetts, Maine, and Connecticut will sue the U.S. EPA for violating clean air laws and imperiling the health of citizens by failing to regulate carbon dioxide emissions, the states’ attorneys general announced yesterday. In a first-of-its-kind lawsuit, the attorneys general will argue that CO2 emissions from burning fossil fuels should be regulated under the Clean Air Act because such emissions are the leading cause of global climate change. The states have a pressing interest in such regulation because climate change “will likely cause or contribute to wide-ranging, adverse changes to just about every aspect of the environment, public health, and welfare throughout the Northeast,” according to a letter sent to EPA Administrator Christie Whitman announcing the intent to sue. If the states win their lawsuit, the EPA would be forced to set standards for CO2 emissions, probably by tightening regulations on power plants — a move the Bush administration has refused to make to date.