Guidelines for Work on Contamined Local Exhaust Systems
Background
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
- Tabletop fume extractors
- Biological safety cabinets, and
- General exhaust systems for isolation rooms.
The majority of local exhaust systems will not have appreciable quantities of contaminants. However, many of the systems have varied use over a prolonged period of time, others are designed for specific high hazard processes. In some cases a thorough investigation may be required to determine the previous usage. Although the majority of the material in ducts will consist of dust, dirt and grit debris from years of accumulation, some contaminants may present a potential hazard to facilities personnel. Therefore, all inside surfaces should be considered contaminated and personal protective equipment should be worn to prevent possible personal exposures. If there is any question about the degree of hazard, Environmental Health and Safety (EH&S) should be called (x5-2060 Cambridge/Allston; 2-1720 Longwood/Southboro) for an evaluation.
Work on these systems may include repairs to duct work, changing exhaust fans, or changing exhaust filters. Routine service work includes repairs and demolition activities.
Preparation for Work
1. Hazard Determination- Lab occupants must provide a history of usage for the local exhaust system with special emphasis on the following factors:
- Perchloric Acid: If perchloric acid was used in a hood, contact Environmental Health and Safety before the hood or duct is disturbed in any way (5-2060 Cambridge/Allston; 2-1720 Longwood/Southboro).
- Radioactive materials: If hood is used for radiation contact the Radiation Protection Office (x5-2060). A radiation survey may be required depending upon the work performed and the type of radiation used.
- Hazardous chemicals: The procedures described here should be adequate for systems using most common laboratory chemicals. If the history of usage indicates that a dangerous material has been used in the system and may have potentially left residue or hazardous byproducts, contact EH&S (5-2060 Cambridge/Allston; 2-1720 Longwood/Southboro) for further assistance.
- Bio Hazards: Laboratory personnel should be disinfecting work areas as part of their ongoing lab procedures. However, a cleaning and disinfection of exterior surfaces should be performed just prior to facilities work. If biological contamination is suspected on the interior of the ductwork, work practices should be used to seal each section of ductwork before and as it is removed to prevent release of bioaerosols. (See "Doing the Work" section.)
- Asbestos: There are several materials that may be encountered when servicing local exhaust ventilation that may contain asbestos. These include the interior panels and working surfaces of a fume hood (sometimes manufactured from "Transite," an asbestos-containing cement board), an outer coating on ducts that may be an industrial material known as "Galbestos" (used to minimize heat exchange and to dampen sound; it is usually black), or some types of vibration dampers. Surrounding building materials may also contain asbestos (ceiling tiles, wallboard/joint compound, pipe insulation, etc.). These materials should not be disturbed until the presence or absence of asbestos has been verified. This may be accomplished by reviewing facilities records or by testing, if records are not available. If the work requires disturbing any asbestos containing materials, only licensed asbestos abatement workers can handle or modify these materials. If you have any questions regarding asbestos contact EH&S (5-2060 Cambridge/Allston; 2-1720 Longwood/Southboro).
2. Notifications
- Follow all notification procedures described in the Overview Document - Responsibilities - Support Staff & Contractors section.
- Special notification procedures for local exhaust service: Several locations may share the same exhaust system. Post a shutdown notice at all affected locations.
3. Preparation of work site
- Ensure that laboratory personnel have followed all safety precautions and preparatory measures described in Responsibilities - Laboratory Occupants.
- 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.
- If hot work is needed, obtain a permit from the Fire Marshal's Office and be sure the appropriate "Hot Work" safety requirements are followed.
- Follow Lockout-Tagout requirements as appropriate.
4. Personal Protective Equipment
- Gloves: Tear-resistant gloves are needed when working with sheet metal. Vinyl, neoprene, leather or rubber gloves may be needed for some activities.
- Eye protection: Side shield safety glasses are to be worn while using any hand tool or power tool. Safety goggles may be necessary if aerosols or vapors are generated.
- Respirator: If work will create potential exposure to particulates or aerosols, an evaluation should be done to determine the need for respiratory protection. Harvard University Personnel are not permitted to wear respiratory protection unless they are enrolled in the University Respiratory Protection Program. For information on the Respiratory Protection Program contact EH&S (x5-2060 Cambridge/Allston; x2-1720 Longwood/Southboro)
- Other: Disposable coveralls, hardhats, hearing protection, and other personal protective equipment may be required. If you have any questions regarding the need for additional PPE contact H&S (x5-2060 Cambridge/Allston; x2-1720 Longwood/Southboro).
Doing the Work
1. Aerosol Generation: Avoid the generation of airborne particulates/vapors whenever possible. A light spray of water helps prevent the generation of aerosols. When the interiors of ducts contain significant amounts of dust and debris, as each section of duct is removed, the ends should be sealed with plastic film and duct tape. Large area ducts may benefit from cutting cardboard or other sheets to the size of the duct opening before sealing with plastic film.
2. Unexpected Issues: If unforeseen problems are encountered during the work, inform your supervisor so appropriate steps can be taken.
Completion of activities
1. Clean up work site
- Wash down the area if appropriate. In general, only wet cleaning methods should be used.
- Gather up tarps or drop cloths and clean up area. Don't leave your waste behind for the occupants.
2. Dispose of materials
- Special disposal requirements are usually not necessary for hood components and ductwork, unless special conditions indicate potential hazardous waste sources. If EH&S determines the material in a duct to be Hazardous Waste, special directions shall be given concerning waste disposal on a case by case basis prior to the commencement of the work. If you have any questions regarding hazardous waste contact EH&S Hazardous Waste line at 6-3322.
- Reusable gloves, drop cloths, and/or coveralls may be rinsed or laundered and reused. Disposable or damaged personal protective equipment can be disposed of as regular trash.
3. Hygiene
- Wash hands after service activities.
* These Guidelines are based upon materials developed by the Health & Safety Department at Cornell University.
