Abstract: At 7:00 a.m. on August 1, 2020, an employee was called in to work on his day off. The employee arrived at the mail facility at 8:15 a.m. and began his residential delivery route at approximately 9:15 a.m. The employee was wearing a self-provided ice vest and the temperature was 94 degrees. While delivering the mail, the employee began to experience overheating, dehydration, dizziness, and vision changes. At approximately noontime, the employee began cramping and at 1:00 p.m. he called his supervisor who advised him to return to the mail facility. At 1:20 p.m. the employee arrived at the mail facility and was instructed by his supervisor to proceed to the hospital. The employee drove himself about 10 miles to a local hospital, where he was admitted and treated for acute renal failure, heat exhaustion and hyperglycemia.