Airman 1st Class Forrest Collins, 28th Medical Group bioenvironmental engineer technician, examines heat-stress readings on a wet-bulb globe thermometer used to determine the work and rest cycles for outside workers here, July 29. The wet-bulb globe thermometer measures heat stress by combining humidity, radiant heat and dry heat into one reading. (U.S. Air Force photo/Airman 1st Class Adam Grant)