Close the sash when you are not working in your hood. Hoods in multiple labs often share the same exhaust fan and may depend on the one your hood is using. Keep the lab door closed to ensure that the lab remains under negative pressure with respect to the hallway. Conduct all work at least six inches inside the hood. This distance ensures that the chemical fumes or vapors are more likely to remain inside the hood.
Fume hoods are important safety devices, but they are only useful when used and maintained properly.
Follow these safety procedures to reduce your potential exposure to harmful substances and to keep your hood working properly.