On March 10, 2009, the U.S. Environmental Protection Agency (U.S. EPA) issued a proposed rule that would require large emitters of greenhouse gases to report their emissions. The proposed rule—if adopted in substantially similar form—could affect airports directly by, for example, requiring reporting of GHG emissions from large stationary sources like boilers. U.S. EPA also has requested comment on other possible reporting requirements that would affect airports. Comments will be due 60 days from publication in the Federal Register.