On July 20, the U.S. Court of Appeals for the District of Columbia Circuit rejected environmental groups’ challenge to an EPA rule allowing exemptions for emissions from natural events when determining compliance with National Ambient Air Quality Standards (NAAQS) for particulate matter and ozone. The environmental groups claimed that EPA had improperly defined “exceptional events” and illegally excluded man-made emissions. According to the Petitioners, many of the rule’s exemptions are not “natural,” creating a “significant loophole” exempting, among other things, dust from roads and forest fires caused by human activity. Congress amended the Clean Air Act in 2005, requiring EPA to issue new regulations accounting for air emissions from natural events. EPA issued regulations addressing exceptional events in 2007, but then amended the rules in 2016 to exclude “reasonably controlled” man-made emissions from the NAAQS, leading to the environmental groups’ petition for review. The D.C. Circuit, however, found that EPA reasonably included exceptional events where both humans and nature contribute to their cause, such as roadway dust, so long as reasonable efforts are used to control the cause.