The U.S. took the first step toward regulating carbon dioxide emissions from aircraft last week when the Environmental Protection Agency determined that these releases endanger the health and welfare of current and future generations. EPA’s move establishes the reasoning for Clean Air Act standards for CO emissions from aircraft. Domestic and international flights originating in the U.S. account for 3% of the nation’s greenhouse gas emissions, according to the agency. EPA’s expected CO2 regulations would affect aircraft as small as the Embraer E170 and as large as commercial jetliners including the Airbus A380 and the Boeing 747. The agency doesn’t indicate what those future emission standards might be. However, EPA points out that it and the Federal Aviation Administration traditionally work through the International Civil Aviation Organization (ICAO) to help establish international emission standards for aircraft. Then, EPA issues U.S. standards that are at least as strict as those set by ICAO, the United Nations’ aviation agency. ICAO is expected to approve CO2 standards for aircraft in October and formally adopt them in March 2017.