Whether adding one or 100 fume hoods to a laboratory, planning is critical. Each hood is affected by the room’s ventilation and traffic flow. When selecting a fume hood location, operator convenience, work flow, and exhaust duct locations should all be considered. It is both inconvenient and dangerous to install a fume hood so that the operator is forced to work in the line of traffic movement. The presence of cross drafts will adversely affect the performance of the fume hood so it is a good idea not to locate the fume hood near open doors and windows.