Fume Hoods

Fume hoods are the most reliable and efficacious method of reducing airborne exposure of laboratory personnel to hazardous materials. By following the basic rules of correct fume hood use, personnel exposure can be reduced to negligible levels.

Fume Hood Face Velocity and Testing

    • EH&S certifies all fume hoods at least once/year.
    • Fume hoods are deemed passing if they have a mean face velocity of 100-150 ft./min.
      • After passing the re-certification test, EH&S will update the yellow certification sticker attached to your fume hood.
    • Face velocity is measured in the vertical plane of the sash between 12 and 16 inches.

Fume Hood Failure

  • If a fume hood fails, an EH&S technician will place a sign on the front of the hood stating, “WARNING Do Not Use”.
  • EH&S will then submit a work order with FMS to repair the fume hood; there is no need for the lab to submit one.
  • Following repair, an EH&S technician will return to the affected hood and retest it.
    • If it fails again, the same procedure outlined above will be followed.
    • If it passes, an EH&S technician will update the yellow certification sticker attached to your fume hood.

Working Inside a Fume Hood

  • Ensure the sash height remains between 12 and 16 inches.
  • Do not be use as a general storage area for chemicals.
  • Make certain that no items obstruct the airflow.
    • If deemed essential, equipment must be lifted at least two inches off the base, be no closer than four inches to the rear or sides of the hood and more than six inches from the front of the hood.
  • Never position fans or air conditioners to direct air flow towards or across the opening.
  • Never remove side panels.
  • Close laboratory doors when in use.
  • Ensure the hood is suitable for the work planned (e.g., DO NOT heat perchloric acid in a regular fume hood).

NOTE: It is advisable to affix a strip of tissue paper or a small card tag on a string to the bottom of the sash. The tissue paper or tag will be sucked inwards by the airflow during normal operation of the hood.

Using the Fume Hood

  • Never allow your head to enter the plane of the hood opening.
  • Close the sash when the hood is not in use.
  • Always wear appropriate PPE — working inside of a fume hood does NOT eliminate the need for appropriate PPE. NOTE: A fume hood sash is not a replacement for appropriate eye protection.
  • The sash is not a blast shield and should not be used in lieu of one.
  • Ensure tissue paper and other light materials are not placed in a hood without restraining them in some way. Unrestrained light items may be sucked into the ductwork.
  • Ensure a sign is displayed if unattended experiments are running.

If your fume hood is alarming or you are concerned about impaired function:

  1. Discontinue use of the fume hood.
  2. Contact the EH&S Lab Safety team at labsafety@usc.edu.

For more detailed information on fume hoods, please reference the Chemical Hygiene Plan.