Abstract: On August 2, 2010, Employee #1 was working as a floor hand moving a rig as part of a mobile drilling operation. The employee was working outside and the temperature that day was 95 degrees Fahrenheit. The employee's shift started at 6:00 a.m. and later that day, the employee vomited and did not look well. A coworker suggested he take a break. Employee #1 was taken to the doghouse to take a break and then into the Rig Manager's trailer for observation and to recover. Employee #1 was offered medical care several times and refused it. He was observed the entire remainder of his shift in an air conditioned environment and given water and did not appear to be in any distress. After work, while at home, at approximately midnight, the employee asked to be taken to the local hospital. Employee #1 was hospitalized for heat cramps and heat exhaustion. The causal factors of the heat cramps and heat exhaustion were both occupational and nonoccupational, with significant exertion occurring both before and after the work shift making it impossible to assign a relative weight to the cause.