Between September 2016 and January 2017, the Occupational Safety and Health Administration issued five citations to the United States Postal Service, each alleging that it committed a repeat violation of the Occupational Safety and Health Act’s general duty clause, 29 U.S.C. § 654(a)(1), by exposing employees to an “excessive heat” hazard. These citations relate to medical incidents involving a total of seven letter carriers working in five different cities during the summer of 2016. In each incident, the letter carrier began feeling ill while delivering mail and subsequently was treated at a hospital or urgent care clinic. With one exception, the Secretary alleges that each carrier became ill due to excessive heat. The Postal Service contested each citation, resulting in five separate cases, each involving the occurrence of an alleged violation in the following cities —San Antonio, Texas (Docket No. 16-1713); Des Moines, Iowa (Docket No. 16-1813); Benton, Arkansas (Docket No. 16-1872); Houston, Texas (Docket No. 17-0023); and Martinsburg, West Virginia (Docket No. 17-0279).