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Subchapter 7. General Industry Safety Orders
Group 16. Control of Hazardous Substances
Article 107. Dusts, Fumes, Mists, Vapors and Gases

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§5154.2. Ventilation Requirements for Biological Safety Cabinets.

(a) Scope and Application. When biological safety cabinets, as defined below, are used to prevent harmful exposure from biohazard agents or biohazardous materials or hazardous substances they shall conform to the provisions of this Section and Section 5143.

Exception: Inspection doors or clean-out doors in exhaust ducts required by Section 5143(a)(3) do not apply to exhaust systems used in conjunction with biological safety cabinets.

(b) Definitions.

Biohazard agent means a replication capable pathogen which is a disease causing microorganism and is capable of causing diseases in humans including viruses, microbes and sub viral agents. The agent includes the agent, products of infectious agents, or the components of infectious agents presenting a risk of illness or injury.

Biohazardous materials are any materials that would harbor biohazardous agents such as human blood, body fluids, or tissues that may be contaminated with biohazardous agents.

(3) Biosafety level. Biosafety levels consist of laboratory practices and techniques, safety equipment, and laboratory facilities appropriate for the operations performed and the hazard posed by the particular biohazard material. The National Institute of Health, Centers for Disease Control defines four levels of biosafety in HHS publication No. 93-8395, "Biosafety in Microbiological and Biomedical Laboratories", 1993. The publication states criteria for the determination of appropriate biosafety levels for microorganisms not listed.

(4) Biological safety cabinet. A ventilated cabinet which serves as a primary containment device for operations involving biohazard agents or biohazardous materials. Three classes of biological safety cabinets are described below:

Class I. The Class I biological safety cabinet is an open-fronted, negative pressure, ventilated cabinet. Exhaust air from the cabinet is filtered by a high efficiency particulate air (HEPA) filter and discharged without internal recirculation. This cabinet may be used in three operational modes; with a full width open front, with an installed front closure panel not equipped with gloves, and with an installed front closure panel equipped with arm-length protective gloves.

Class II. The Class II vertical laminar flow biological safety cabinet is an open fronted, ventilated cabinet. Exhaust air is filtered with a high efficiency particulate air filter (HEPA). This cabinet provides HEPA-filtered downward air flow within the workspace. Class II biological safety cabinets are further classified as type A, type B1, type B2, and type B3. Class II type A cabinets may have positive pressure contaminated internal ducts and may exhaust HEPA filtered air into the laboratory. Class II type B1 cabinets have all biologically contaminated internal ducts or plenums under negative pressure or surrounded by negative pressure ducts or plenums, exhaust HEPA filtered air through external ducts to space outside the laboratory, and have HEPA filtered downflow air composed largely of unrecirculated inflow air. Class II type B2 cabinets (also know as "total exhaust" cabinets) have all biologically contaminated internal ducts or plenums under negative pressure or surrounded by negative pressure ducts or plenums, exhaust HEPA filtered air through external ducts to space outside the laboratory, and have HEPA filtered downflow air drawn from the laboratory or outside air. Class II type B3 cabinets (also known as "convertible" cabinets) have all biologically contaminated internal ducts or plenums under negative pressure or surrounded by negative pressure ducts or plenums, exhaust HEPA filtered air through external ducts to space outside the laboratory, and have HEPA filtered downflow air that is a portion of the mixed downflow and inflow air from a common exhaust plenum.

NOTE: Design, construction, and performance standards are available from the NSF International (the National Sanitation Foundation), Ann Arbor, Michigan. That standard is "National Sanitation Foundation Standard 49 Class II (Laminar Flow) Biohazard Cabinetry".

Class III. The Class III biological safety cabinet is a totally enclosed, negative pressure, ventilated cabinet of gas-tight construction. Operations within the Class III cabinet are conducted through attached protective gloves. Supply air is drawn into the cabinet through high efficiency particulate air filters. Exhaust air is filtered by two high efficiency particulate air filters placed in series or by high efficiency particulate air filtration and incineration, and discharged to the outdoor environment without re-circulation.

(5) Hazardous Substance. One which by reason of being explosive, flammable, poisonous, an irritant, or otherwise harmful is likely to cause injury or illness.

(6) High-efficiency particulate air (HEPA) filter. A filter capable of trapping and retaining at least 99.97 percent of all mono-dispersed particles 0.3 micrometers in diameter.

(c) Use. Where biological safety cabinets are used to prevent exposure to biohazard materials they shall be used according to the biosafety level assigned by the National Institute of Health, Centers for Disease Control, in HHS publication No. 93-8395, "Biosafety in Microbiological and Biomedical Laboratories", 1993, to the particular microorganism, HHS publication No. 93-8395, "Biosafety in Microbiological and Biomedical Laboratories", 1993, is available from the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 and is hereby incorporated by reference. When a particular microorganism is not assigned a level or listed, the criteria given in that publication shall be used to determine the appropriate biosafety level.

Class II biological safety cabinets may be used to prevent harmful exposure to cytotoxic agents during their compounding or preparation for parenteral use. Biological safety cabinets may be used to control harmful exposure to aerosols and particulate matter, provided the presence of the substance in the biological safety cabinet does not present a risk of fire or explosion. When biological safety cabinets are used to control exposure to these hazards they shall meet the requirements of this Section.

NOTE: The U.S. Department of Labor recommends the use of externally vented biological safety cabinets for the preparation of cytotoxic drugs in its work practice guidelines for cytotoxic drugs, OSHA Instruction PUB 8-1.1, January 29, 1986.

(d) Operation. In addition to the operation requirements of Section 5143(b) the mechanical ventilation system used to provide air flow and or negative pressures shall be operated until readily accessible interior surfaces are decontaminated. The manufacturers' recommendations for start-up and shut-down should also be followed. In the absence of such procedures, Appendix B contains a suggested start up and shut down procedure for Class II biological safety cabinets, the manufacturers' recommendations should also be followed.

(e) Ventilation rates and negative pressure. All Class I and II biological safety cabinet face velocities shall be sufficient to maintain an inward flow of air at all openings into the cabinet under operating conditions.

(1) The mechanical ventilation system in a Class I biological safety cabinet shall provide a minimum inward average face velocity of 75 linear feet per minute at the work opening.

(2) The mechanical ventilation system in a Class II type A biological safety cabinet shall provide a minimum inward average face velocity of at least 75 linear feet per minute at the work opening.

(3) The mechanical ventilation system in a Class II type B1, type B2, and type B3 biological safety cabinet shall provide a minimum inward average face velocity of at least 100 linear feet per minute at the work opening.

(4) The mechanical ventilation system in a Class III biological safety cabinet shall provide sufficient air flow to maintain a constant purging of the work area of hazardous vapors, gases or particulate generated within the cabinet and to dilute flammable dusts, gases, or vapors to below 20% of the lower explosive limit (LEL) at a minimum negative pressure inside the cabinet of 0.5 inches of water gauge.

(f) Airflow measurements and HEPA filter leak testing. Biological safety cabinets shall be tested after installation, alterations, or maintenance, and at least annually. Records of tests performed shall be retained for at least five years.

(1) The ventilation test requirements for Class I biological safety cabinets are as follows:

(A) Velocity measurements shall be made at the work opening of the cabinet with a calibrated anemometer.

(B) A quantitative aerosol challenge test shall be performed on each high-efficiency particulate air filter. The test must be capable of detecting penetrations exceeding 0.005% of particles 0.3 micrometers or larger while the cabinet is in normal operation. Any measurement exceeding 0.03% penetration shall establish a failure of the test. Appendix A contains a recommended high efficiency particulate air filter test protocol.

(C) The ability of the hood to maintain an inward flow as required by subsection (e) above shall be demonstrated using smoke tubes or other suitable qualitative methods.

(2) The ventilation test requirements for the Class II biological safety cabinets are as follows:

(A) For type A and B3 cabinets the average intake face velocity at the normal operating work access opening shall be determined by measuring the exhaust air velocity, calculating the cabinet's exhaust air volume, and dividing this volume by the open area of the work access opening. Average face velocity is calculated by the following equation: (average exhaust velocity X open area of HEPA filter or exhaust port) ö (area of normal work access opening) = average face velocity.

Exception: Cabinets in which the exhaust filter is not accessible can be measured directly at the work access opening using a calibrated total capture air flow hood to measure the air volume entering the cabinet, and dividing this measurement by the area of the work access opening to determine the average face velocity.

(B) For type B1 cabinets the average intake velocity shall be determined by directly measuring the inflow velocity at the normal operating work access opening with the cabinet recirculating blower turned off. A calibrated total captured airflow hood may be used for type B1 cabinets as in (A) above.

(C) For type B2 cabinets the average face velocity shall be calculated based on total exhaust air volume (velocity measurement at exhaust port), supply airflow volume, and work access area. Average face velocity is calculated by the following equation: [(average exhaust velocity X area of exhaust port) - (average supply downflow velocity X open area of supply HEPA filter)] ö (area of normal work access opening) = average face velocity.

Exception: Average intake velocity can also be measured directly at the work access opening using a calibrated total capture air flow hood to measure the air volume entering the cabinet, and dividing this measurement by the area of the work access opening to determine the average face velocity.

(D) A quantitative aerosol challenge test shall be performed on each high-efficiency particulate air filter. The test must be capable of detecting penetrations exceeding 0.005% of particles 0.3 micrometers or larger while the cabinet is in normal operation. Any measurement exceeding 0.03% penetration shall establish a failure of the test. Appendix A contains a recommended high efficiency particulate air filter test protocol.

(E) The ability of the hood to maintain an inward flow as required by subsection (e) above shall be demonstrated using smoke tubes or other suitable qualitative methods.

(3) The ventilation test requirements for Class III biological safety cabinets are as follows:

(A) The airflow through the Class III biological safety cabinet shall be determined by measuring the exhaust velocity at the exhaust port. Total air volume is calculated by the following equation: (exhaust velocity) X (area of exhaust port) = total air volume. The air change rate for a class III biological safety cabinet shall be a minimum of 1 air change in 3 minutes or airflow required to maintain flammable gases/vapors below 20% of the LEL whichever is greater. The measurement of the negative pressure inside the cabinet shall be made with a calibrated gauge. The accuracy of the gauge shall be +5% at the required 0.5 inches of water gauge.

(B) A quantitative aerosol challenge test shall be performed on exhaust HEPA filters. The test must be capable of detecting penetrations exceeding 0.005% of particles, 0.3 micrometer or larger while the cabinet is in normal operation. Any measurement exceeding 0.03% penetration shall establish a failure of the test. Appendix A contains a recommended high efficiency particulate air filter test protocol.

(g) Special requirements.

(1) All test or maintenance activities requiring access to potentially contaminated interior spaces of the cabinet shall be performed after appropriate decontamination.

(2) A warning placard shall be placed on the front of the cabinet requiring decontamination prior to opening any service panel or other interior access.

(3) Where biological safety cabinets are attached to external duct systems with a blower and the cabinet system also contains a blower, or where the cabinet uses an external blower, an audible and visual alarm system to alert the user indicating the loss of exhaust flow in the external duct shall be used. Biological safety cabinets which are served with a canopy or thimble connected exhaust system shall have a ribbon streamer or like device attached to the edge of the canopy or thimble to indicate the direction of flow and are exempt from the requirement for flow alarms.

(h) Appendices. The information contained in the appendices is not intended, by itself, to create any additional obligations not otherwise imposed or detract from any existing obligation.

(i) Implementation. The requirements of subsection (g)(2) and (g)(3) shall be complied with no later than one year from the effective date of this Section. All other requirements of this Section shall be complied upon the effective date of this Section.

NOTE: Authority cited: Section 142.3, Labor code. Reference: Section 142.3, Labor Code.

Appendix A
Appendix B

HISTORY

1. New section filed 10-11-94; operative 11-10-94 (Register 94, No. 41).

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