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Environmental Health & Safety



These guidelines are designed to assist Facilities personnel working on local exhaust systems.


Some of these systems may be contaminated and may require evaluation before work is performed. By establishing the appropriate work practices and utilizing the proper personal protective equipment, employees will be able to accomplish their tasks successfully and safely.


A variety of local exhaust systems can be found at the University. They may include:

  • chemical fume hoods
  • canopy hoods
  • slot hoods
  • flammable storage cabinet exhaust systems
  • elephant trunks
  • student tabletop fume extractors
  • biological safety cabinets*
  • dust collection systems
  • general exhaust systems for isolation rooms

    * Work on the filters and blowers for biological safety cabinets must be performed only by an outside contractor, certified to work on such units through NSF/ANSI 49.

Many of the systems have been in use for prolonged periods of time or may have been a special use system and an evaluation may be required to determine the previous usage. Some contaminants may present a potential hazard to Facilities personnel. If there is any question about the degree of hazard, Environmental Health & Safety (EH&S) Occupational Safety Unit should be called (275-3241) for an evaluation.

Work on these systems may include repairs to duct work, changing exhaust fans, or changing exhaust filters. Special precautions are not required when working on systems outside of the airstream. Examples of such work may include changing belts, replacing bearings, or replacing motors.


Routine service work includes repairs and demolition activities. The majority of local exhaust systems will not have appreciable quantities of contaminants. Although the majority of the material will consist of dust, dirt and grit debris from years of accumulation, all inside surfaces should be considered contaminated and personal protective equipment should be worn to prevent possible personal exposures.

  1. Work Practices/Procedures
  2. Facilities employees must gather information to establish appropriate work practices to complete the project. Did the occupants use radioactive materials, hazardous chemicals, or biohazardous materials in the system? Is asbestos present in a hood or on the duct work?

    1. Hazard Determination: Obtain a history of usage for the local exhaust system from the occupants:
      1. If radioactive materials were used in the system, contact the Radiation Safety Unit at 275-3781 for an evaluation.
      2. If hazardous chemical or biohazardous materials were used in the system, contact the Occupational Safety and/or Biosafety Unit at 275-3241 for an evaluation.
      3. If perchloric acid was used in a hood, contact Occupational Safety at 275-3241 before the hood or duct is disturbed in any way.
      4. If the work may involve disturbing transite (asbestos) or galbestos (a black mastic which contains asbestos applied to ductwork), contact the University's Asbestos Control Group at 275-3241 before work is started. The interior panels and working surfaces of a fume hood may contain asbestos and must not be disturbed. Only licensed asbestos abatement workers can handle or modify these materials.
    2. Notifications
      1. The Facilities supervisor is to coordinate the work if a shutdown is needed.
      2. Laboratory personnel or others affected need to be informed of the details of the shut down (duration, systems affected, contact name to report problems).
      3. Several locations may share the same exhaust system. Post the shutdown notice at all affected locations.
    3. Preparation of work site
      1. Avoid potential exposures from hazardous vapor/fumes that are being generated or present in the hood. Have laboratory personnel move equipment or chemicals present in the hood's immediate work area to a safe location.
      2. If the work activities may result in the release of dust or metal fragments, cover the work area with a tarp/drop cloth to minimize any required clean up.
      3. If hot work is needed, obtain a permit from the Fire Marshal's Office (275-3241) and be sure the appropriate "Hot Work" safety requirements are followed.
      4. Shut down the necessary systems (unless task requires that the system is operational)
        1. Follow required Lockout-Tagout requirements (lockout or tagout switch/equipment per written protocol, electric, natural gas, etc.).
        2. If more than one person is working on the system, use multiple lockouts.
        3. Check system to be sure the system is de-energized prior to work.
    4. Doing the Work
      1. Wear the personal protective equipment required to prevent possible exposures or injuries (see PPE Section).
      2. If problems are found, inform your supervisor so appropriate steps can be taken.
      3. Avoid the generation of airborne particulates/vapors when possible. A light spray of water helps prevent the generation of aerosols.
    5. Completion of activities
      1. Clean up work site
        1. Wash down the area if appropriate
        2. Dry cleanup methods for particulates are generally not appropriate when cleaining contaminated exhaust systems. Neither brooms or a vacuum cleaner should be used to clean up particulates unless the unit and workplace practices have been approved by Occupational Safety. Vacuum with HEPA filtration is the preferred equipment for cleanup.
        3. Gather up tarps or drop cloths and clean up area. Don't leave your waste behind for the occupants.
      2. Dispose of materials
        1. Occupational Safety will discuss with the Environmental Compliance Unit the management of any possible hazardous waste that may be generated as a result of an established work practice or protocol. Testing performed to date on heavily used systems has shown no regulated chemical hazardous waste to be present in interior of the exhaust systems. Therefore, no special disposal requirements are usually necessary. Should testing determine some components are contaminated with hazardous materials, the Environmental Compliance Unit will determine the appropriate disposal methods required.
        2. The scrap metal that is no longer needed should be recycled.
        3. Gloves, drop cloths, and/or coveralls may be rinsed or cleaned and reused. Disposable or damaged personal protective equipment can be disposed of as regular trash.
  3. Personal Protective Equipment
    1. Gloves - When handling sheet metal, you must wear cut-resistant gloves. Insulated gloves are worn when handling hot or cold surfaces or working in cold climates. To protect against biological and chemical agents while working on plumbing and sewage systems, chemical-resistant gloves are required. In accordance with the scope of the job, nitrile gloves may be worn. If employees working with live electircal at 50 volts or more, rubber and leather gloves are required.
    2. Eye protection - Side shield safety glasses must be worn while cutting material, working above ceiling and in mechanical spaces. Safety goggles are required when mixing or pouring chemicals into secondary containers, or when using chemicals where splashing can occur. Tasks that generate a large amount of dust may require safety goggles. Face shields shall be worn when working where there is the possibility of flying objects, working with chemicals, molten metal, acits or caustic liquids. Safety glasses or goggles are required when wearing face shields.
    3. Respirator
      1. A hazard assessment must be performed to determine whether an N-95 particulate respirator, half or full face cartridge respirator, or PAPR (powered air-purifying respirator) should be used. Personnel must observe all of the requirements of the University's Respirator Protection Program.
      2. Consult Occupational Safety at 275-3241 if a different respirator or cartridge is to be used.
    4. Disposable coveralls, hardhats, hearing protection, and other personal protective equipment may be required. Occupational Safety should be contacted to determine the required PPE for some applications.


Procedures must be instituted to accomplish the work tasks in a safe manner. Some work may have to be coordinated with Occupational Safety to establish the necessary work protocols. Adequate notification to Occupational Safety of the proposed work is required.

Contact EH&S at (585) 275-3241 or e-mail EH&S Questions.

This page last updated 9/23/2022. Disclaimer.