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Chemical Fume Hood Use Guidelines

Follow these required guidelines to use fume hoods safely and avoid compromising their efficiency.

Be aware of the limitations of a fume hood.

Chemical fume hoods reliably help protect you from chemical hazards when properly used, but they do have limitations.

  • Read Chemical Fume Hoods Overview to learn about how fume hoods protect you and about their limitations.
  • Wear appropriate personal protection equipment when working with chemicals, even when work is conducted in a fume hood. At a minimum, wear the following:
    • Eye protection (safety glasses, goggles, and face shield as appropriate)
    • Gloves
    • Lab coat

Verify the fume hood is operating properly.

  • Before beginning work in a chemical fume hood do the following:
    1. Confirm the fume hood has been certified within the last 12 months.
      • If the date on the certification sticker is more than 12 months, contact EH&S immediately for action:
    2. Confirm the fume hood monitor is functioning properly - both visual and audio components indicate normal operation.
      • If either the visual or audio component appears to be in alarm mode, contact EH&S and Facilities Management, (858) 534-2930, immediately. Stop all work in the hood until the problem is corrected.
    3. Confirm air is flowing into the hood before use. To check air flow:
      • Tape a strip of tissue (Kimwipe) onto the sash. It will flutter as air current blows by.
  • Keep baffles at the back of the hood unobstructed and intact.
  • Keep the air foil along the front bottom edge of the fume hood in place at all times. Removing the air foil or altering its position can seriously impact the proper air flow of your fume hood.
    • Avoid allowing electrical cords or hoses to impede the proper functioning of the bottom air foil or sash.
  • Keep hoods free of clutter and avoid using them for storage. If absolutely necessary, position equipment deep inside the hood and maintain an air gap around and below the experiment to maintain air circulation.
  • Avoid creating cross-drafts or air currents near the hood. They'll pull contaminated air out of the hood and into the breathing zone. Air currents can be caused by:
    • Air ventilation in the room
    • Open doors or windows
    • People walking by the hood
    • Rapid arm or body movement
  • View the "Proper Use of a Fume Hood" video for a demonstration of how air currents and drafts can affect fume hood operation.
  • Don't modify the fume hood or exhaust system without approval from Environment, Health & Safety (EH&S).

Adjust baffles (if available) for best performance.

Some fume hoods are equipped with upper and lower baffles in the back that can be adjusted using a lever on the front of the hood.

  • Adjust the baffles based on the type of work being done in the hood.

Practice safe operating procedures.

  • Keep the sash closed as much as practical for increased safety and for energy conservation.
    • Note: It has been shown that average annual consumption of energy per fume hood is roughly equal to operating 3 average American homes. Keeping the sash closed as much as possible will help reduce energy demands at UCSD.
  • Avoid raising the sash above the arrow marking efficient operating level, except during setup. See Chemical Fume Hoods Overview for more information.
    • For hoods with horizontal sliding panes, position the sash all the way down, with as small an open area as practical.
  • Work at least 6 inches inside the hood to improve capture of contaminates.
  • Elevate large equipment (e.g., a centrifuge) at least 2 inches off the base of the hood interior.
  • Be sure that nothing blocks the airflow through the baffles or through the baffle exhaust slots.
  • If you heat perchloric acid, use a wash-down hood only. Contact EH&S for more information.
  • Don't use the hood to evaporate unwanted solvents or spills.
  • Clean up spills immediately and dispose of waste solvents as hazardous chemical waste.

Request a decontamination clearance.

Equipment that may have come in contact with radioactive, biohazardous, or chemical materials must be decontaminated before you have it serviced, repaired, moved, sent to Surplus Sales, or otherwise disposed of.

  • Read How to Get a Decontamination Clearance for Equipment or Facilities for details.
  • If you're closing or moving a lab, read How to Close or Relocate a UCSD Laboratory.
  • Important: Improper heating of perchloric acid in chemical fume hoods is potentially dangerous, violates regulatory requirements, and goes against all good practice.
    • If perchloric acid has been improperly heated in your chemical fume hood, or if you are unsure about the history of the fume hood (e.g., digestion of minerals), contact the Chemical Hygiene Officer for guidance and requirements.
    • The chemical safety officer will research the historical use of the fume hood and present the findings to the responsible party. The following conditions must be met before the clearance process can be completed:
      • If evidence does not suggest improper heating has occurred, the fume hood will be cleared according to the standard clearance requirements above.
      • If evidence suggests improper use, testing is required by a qualified outside vendor. The PI or department responsible for the fume hood is responsible for the testing service.
      • If testing is performed and the results are positive for perchlorate contamination, remediation of the chemical fume hood and associated duct work must be performed by a qualified outside vendor before the room and fume hood can be cleared. The PI or department responsible for the equipment is responsible for the remediation.


For more information, contact an EH&S Research Assistance Program specialist.
Notice: Disposal of hazardous waste using sinks, intentional evaporation, or as regular trash is against the law. Campus laboratories must abide by strict state and federal waste disposal requirements. You may be held liable for violations of applicable laws.