The back baffle was devised so as to more evenly distribute the air across the face of the hood proper. This back baffle system in its proper adjustment constitutes one of the major areas of fume hood design. Consider that the hood air patterns are divided into two segments: floor sweep and vortex. The floor sweep is that area from the work surface to a point approximately 8 in. above the work surface. Air entering the hood at the work surface not only comes from directly in front of the hood face but also up from the area in front of the hood base cabinets. Never judge that a hood is working well just because it makes a lot of noise. Fume hoods, like the stove in an efficient kitchen, should be located for convenience to the user not the building contractor or ventilation engineer. They should also be located away from major traffic patterns and major air patterns.