EE was inspecting the drive belts and conveyor belt for tension. Conveyor is located in a storage building (250'longX130'wideX68'high). Conveyors runs length of building and has catwalks on both sides. Conveyor is located 50' above ground level. Air temp outside est close to 100 the temp inside building @ conveyor level est 115 +. Was walking on catwalk and passed out.