Safe Use of Chemical Fume Hoods Always work with the sash at the proper operating level as indicated by the arrows, usually no more than 12-18 inches open. Make sure that the exhaust blower is operating and air is entering the hood, prior to starting an experiment. This can be visually checked by holding a strip of paper up to the sash and observing it being pulled into the hood. Do not place your face inside the hood. Keep as much of your body outside of the hood as possible. Keep all items at least six (6) inches from the front and rear of the hood to allow for proper air flow. Do not block off baffle exhaust slots in any manner. Elevate large equipment two (2) inches off the base of the fume hood when six (6) inch clearance cannot be maintained. Chemical fume hoods are not appropriate storage areas for any but working quantities of chemicals. If working amounts of volatile materials are stored in the hood, the hood must remain in operation. Clean up spills immediately. Periodically clean hood interior, including fluorescent bulb panel. Be aware of other room ventilation factors that may interfere with your fume hood operation, such as people moving past the hood while in use, lab doors being opened, blocked exhaust ports or heating and air conditioning vents. Minimize these interfering factors as much as possible before work in the hood begins. Avoid cross drafts and disruptive air currents in front of the fume hood. Use the sash as a safety shield when boiling materials or conducting an experiment with reactive chemicals. Prepare a plan of action in case of an emergency, such as a power failure, especially when using extremely hazardous chemicals or acids. Periodically check air flow through the hood using a source of visible smoke or other air flow indicator, such as a Kim wipe. If air flow has changed, check ductwork, blower, etc. to determine cause.