On July 25, the U.S. Environmental Protection Agency (EPA) issued its endangerment
and cause or contribute finding that six greenhouses gases (GHGs) (carbon
dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and
sulfur hexafluoride) in the atmosphere endanger the public health and welfare
and that GHG emissions from aircraft contribute to this air pollution. EPA
the endangerment finding back in July 2015.