Ion implantation is now the most important doping technique for semiconductor devices. Ion implanters have changed from complicated experimental equipment to computer-controlled, automated machines. Semiconductor fabricators are increasingly expecting ion implanters to continually operate at high production efficiencies, with a minimum of the initial set up and testing prior to entering a production regime. These potential exposures can result from a variety of activities including source housing and resolving housing scrubbing, as well as cryo and diffusion pump maintenance, or other activities. These potential exposures are not necessarily predictable based on the frequency of maintenance or on the specific activities performed. The highest potential exposure measured was approximately eight times the OSHA PEL for arsenic.