The outdoor environment includes: noise and dirt; Physical hazards such as powered vehicle, sharp objects, moving machinery, arc-welding, open trenches, and buried electrical and gas utilities; Hazardous materials such as fuels, oils, grease, paint, solvents, coolant, pressurized gases, various acids, cleaners, and metals. The shop environment includes: variable temperature and humidity, noise, and dirt; Physical hazards such as powered vehicle, bicycle, and pedestrian traffic, sharp objects, moving machinery, arc-welding and other electrical equipment, and high-voltage power supplies.