In order to meet the needs of both safety and economy, laboratory ventilation systems must effectively remove air-borne toxic and flammable materials and at the same time exhaust a minimum volume of air. Laboratory hoods are the most commonly used means of removing gases, dusts, mists, vapors, and fumed from laboratory operations. To be effective, a laboratory hood and its associated components must confine contaminants within the hood, remove them through ductwork, and dispense them so they do not return to the building through the fresh air supply system. Hood performance should be assisted by providing ventilated chemical storage cabinets which will require less air flow and which can be exhausted in a separate system 24 hours a day. Suggestions for the improvement of existing fume hoods as well as the design of new hoods is discussed. (RH)