On July 1, 2015, the U.S. Environmental Protection Agency ("EPA") issued a proposed finding that greenhouse gas emissions from aircraft cause or contribute to air pollution that may reasonably be anticipated to endanger public health and welfare within the meaning of § 231(a) of the Clean Air Act (“CAA”) and published an advance notice of proposed rulemaking ("ANPR"). The EPA issued this finding further to a 2011 order issued by the District Court for the District of Columbia. The Court found that § 231(a)(2)(A) of the CAA created a duty upon the EPA to make findings regarding the endangerment caused by greenhouse gas emissions from aircraft, contrary to the EPA's understanding of the section. Despite this finding, the EPA had not made a finding by mid-2014 and plaintiffs put the EPA on notice that they intended to enforce the order by filing suit for unreasonable delay or resolution. If the proposed finding that aircraft greenhouse emissions contribute to air pollution becomes final, § 231 requires the EPA to promulgate domestic aircraft emissions standards. The ANPR provides an overview of issues relating to setting an international CO2 standard for aircraft by ICAO, ICAO's progress at establishing global aircraft standards that achieve meaningful reductions in CO2 emissions and the potential use of section 231 of the CAA to adopt and implement these aircraft engine greenhouse gas emissions standards domestically. There will be a public hearing on August 11, 2015 in Washington DC, and the deadline for public comment is August 31, 2015.