36C25619R0024-007.pdf

Not for Sale

NSF/ANSI 49 – 2016

Annex E

Biosafety Cabinetry: Design, Construction, Performance, and Field Certification

Annex E

NSF International Standard/ American National Standard

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Annex E1 (informative)

Biosafety cabinet selection, installation, lifespan and decommissioning

Table Of Contents

E.1 Institutional safety consultation E.2 Risk assessment procedure E.3 BSC class and type selection E.4 Site review before BSC purchase E.5 BSC arrival inspection and certification E.6 Cleaning and disinfection of BSC work area E.7 BSC use practices and procedures E.8 Moving a permanently installed BSC E.9 BSC lifespan E.10 BSC decommissioning process E.11 Definitions

E.1 Institutional safety consultation

A biosafety professional should be consulted prior to a BSC purchase. Some institutions have biosafety cabinet purchases approved by the biosafety professional after consultation with the user, architect and engineer. Biosafety professionals that perform this function should have training and field experience that includes methods used to control biohazards and knowledge of the design, application, and testing of biosafety cabinets.

Issues that may be considered include:

— risk assessment;

— selecting which kind of BSC is required and if it should be exhausted; and

— assessment of the laboratory environment and the proper location of BSCs within it.

E.1.1 If there is a window in the laboratory, it should remain closed at all times. Cabinets should not be located where room ventilation air inlets blow across the front opening or onto the exhaust filter.

E.2 Risk assessment procedure

E.2.1 Risk assessments encompass four main elements:

— hazard identification;

— exposure assessment;

— dose-response assessment; and

— risk characterization, and risk management (job analysis)2.

1 The information contained in this annex is not part of this American National Standard (ANS) and has not been processed in accordance with ANSI’s requirements for an ANS. Therefore, this annex may contain material that has not been subjected to public review or a consensus process. In addition, it does not contain requirements necessary for conformance to the Standard.

2 Risk Assessment of Biological Hazards, Fleming, D.O., p. 81-91, 2006.. In D.O. Fleming and D.L. Hunt(ed.), Biological Safety: Principles and Practices, 4th ed. ASM Press, Washington, DC.

E.2.2 Risk assessment team members may include:

— investigator/scientist;

— laboratory staff;

— animal care staff when appropriate;

— animal veterinarian when appropriate;

— plant pathogen, or plant pest containment expert when appropriate; and

— occupational health & biosafety professionals.

E.2.3 Risk assessment hazards considered:

— animal hazards;

— agent/pathogen/recombinant hazards;

— chemical hazards; and

— radiological hazards.

E.2.4 Agent/pathogen/recombinant's factors associated with risk of disease or injury:

— virulence;

— infectious dose;

— route of infection (portal of entry);

— toxigenicity;

— agent's host range;

— if the agent is endemic or exotic to the environment it is in;

— availability of effective preventive measures; and

— availability of effective treatment.

E.2.5 Factors associated with worker's risk of exposure:

— worker's work activity; diagnostic, research or production scale;

— worker's proficiency, attitude and safety awareness; and

— worker's age, sex, pregnancy, race, immune status and medications.

E.2.6 Risk management plan includes:

— biosafety containment level assignment to the facility and microbiological practices;

— safety equipment;

— engineering controls;

— personal protective equipment;

— work practices Standard Operating Procedures (SOPs);

— emergency procedures;

— work schedule calendar; and

— investigation protocols that include all risk management plans.

E.2.7 Investigation protocol review includes:

— committee (IBC/IRB/IACUC) review, as appropriate;

— meetings with workers to discuss approved protocols;

— training;

— dry runs without agent/pathogen/recombinant; and

— regular audits.

E.2.8 Risk management analysis table

Risk factors Assessment level

Decrease< >Increase

Pathogen disease potential known, classified suspected, classified known, unclassified >>> unknown >>>>

Pathogen aerosol potential tissue procedure <<< culture procedure >>> concentration procedure >>>>>> animal/non-shedder <<< animal/shedder >>>>>>

Pathogen infectious route respiratory >>>>>> mucous membrane >>> parenteral <<< other <<<

Disease severity moderate >> severe >>> life threatening/lethal >>>>>>>>

Disease prophylaxis none >>>>>>>> vaccine << immune globulin <<< antibiotics <<< antivirals <<<

Other factors livestock pathogen >>> poultry pathogen >>>

E.3 BSC class and type selection

E.3.1 Selecting the proper BSC should be done in several stages:

— Select the proper class and type of BSC required, based on the type of protection needed.

— Establish, if possible, all of the different tasks to be done within the BSC.

— Establish, if possible, all of the different chemicals that may be used in the BSC.

— If the BSC is to be connected to an exhaust system, is it compatible with the BSC’s requirements?

— If the exhaust system malfunctions, does the user understand its impact on the BSC’s ability to maintain personnel and environmental protection, i.e. containment?

These five stages are reviewed in the questions that follow (E.3.1.1 – E.3.1.5), and the various configurations of Class II BSCs are shown in figures E2, E4, E5 and E7.

E.3.1.1 Question one: What needs to be protected?

— Only the material being worked on (product protection)?

— Only the technician and the laboratory (personnel and environmental protection)?

— Or to protect all three (personnel, product, and environmental protection)?

If all that is needed is product protection, then a Unidirectional Flow Clean-Air Device (Clean Air Bench)3, which is not a BSC, may be the unit of choice. Clean Air Devicesuse High Efficiency Particulate Air (HEPA) or Ultra Low Penetration Air (ULPA) filter(s) to remove particulates from room air. This filtered, particulate-free air then flows through an enclosed work area, in a horizontal or vertical direction. These devices bathe the materials inside in filtered air, and then the air is typically discharged into the laboratory. While these devices protect the product from airborne contaminants, any aerosol generated in the work area will be discharged into the laboratory. As such, they cannot be used with toxic or biohazardous materials.

For personnel and environmental protection only, the Class I biosafety cabinet (BSC) enclosure offers a simple and economical solution. Room air sweeps around the operator and through the work area. This contaminated air is then HEPA or ULPA- filtered and discharged into the laboratory or exhausted outside of the building via an external mechanical exhaust system. The Class I BSC will protect the operator and the lab, however, because room air constantly washes over the work area, the product is exposed to airborne contaminants.

Personnel, environmental, and product protection is most efficiently provided by a Class II Biosafety Cabinet. The inflow of air around the operator provides personnel protection, HEPA or ULPA-filtered air flowing downward through the work area provides product protection, and the discharge of exhaust HEPA or ULPA filtered air provides environmental protection.

E.3.1.2 Question two: What are all of the different types of work to be done in a Class II BSC?

One of the most difficult tasks in selecting a BSC is trying to foresee all the different types of work that will be taking place in it. It is critical to decide what things need protection, both now and in the future. All too often users purchase a Clean Air Device or Class I BSC for current applications, only to find these devices are unsuitable as their work requirements change.

E.3.1.3 Question three: What types and quantities of chemical vapors will be generated in the BSC?

As important as the preceding question, the user must also foresee the types and quantities of chemical vapors that will be generated in the cabinet. Because chemical vapors can freely pass through HEPA or ULPA filters, both Class I and Class II BSCs must be exhausted out of the laboratory when used with these types of chemicals. For the Class II BSCs, Types B1 and B2 must be direct connected to an external exhaust system in order to operate properly; Types A1, A2 and C1 can be converted to operate in either a canopy ducted or recirculating mode, depending on the users’ requirements. The airflow patterns of Types A1, A2, B1, B2 and C1 Biosafety Cabinets are shown in figures E2, E4, E5 and E7, respectively.

3 IEST RP CC002, latest revision

Class II BSCs typically do not feature explosion-proof electrical components in their work area or internally.

Therefore, use of flammable or explosive materials in quantities above their explosive limit are not recommended.

Types of chemicals used in cabinet should be considered as some can destroy the filter medium, housings and gaskets causing loss of containment.

The percentage of air in the work area that is recirculated within the BSC versus exhausted varies, based on the BSC type, subtype, and in some cases, where the chemicals are released in the work area.4 5 6

When flammable or explosive chemicals are to be used in a BSC, it is the users’ responsibility to:

— be fully cognizant with the properties of chemical(s) and the hazards associated with them;

— calculate the highest percent of recirculation that may occur in the BSC being used;

— ensure the concentration of chemical(s) released in the work area do not exceed their explosive limit;

— utilize the lowest quantities of the chemical(s) required for the procedure being performed, and;

— have appropriate spill/splash cleanup procedures in place before using the chemical(s).

E.3.1.4 Question four: If the BSC requires an exhaust system, is there an appropriate location for the cabinet and its ductwork?

If a BSC is going to recirculate its HEPA- or ULPA-filtered air back into the laboratory, then the user has some freedom as to where the unit can be installed, provided it is out of major traffic areas, and there are no other air handling devices in the area, as shown in figure E1.

If a BSC must be connected to an external mechanical exhaust system, their compatibility must be established before the BSC is selected. The exhaust system configurations of Type A, Type B, and Type C1 BSCs are shown in figures E3, E6 and E8, respectively.

— directly ducting Types A and C1 cabinets is not permitted; they shall only be exhausted through a properly designed and fitted canopy exhaust system.

— canopy-connected Types A and C1 require a consistent, low static pressure. While a dedicated exhaust system is preferred, they may share a common exhaust system with other exhausted laboratory devices, if properly balanced.

— Type B BSCs require a higher static pressure that must increase as their exhaust filters load. They must be on a dedicated exhaust system, and not be ganged with other Type B BSCs, or other exhausted laboratory devices requiring a lower static pressure (e.g. fume hoods, canopy-connected BSCs).

4 Industrial Ventilation: A Manual of Recommended Practice for Design. “Industrial Ventilation – Dilution Ventilation for Health”. American Conference of Governmental Industrial Hygienists, Inc., Cincinnati, OH. 28 th edition 2013 or latest edition.

5 2007 ASHRAE Handbook: Heating, Ventilating and Air-Conditioning Applications. “Industrial Applications – Chapter 14 Laboratories”. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA. or latest edition.

6 ASHRAE Laboratory Design Guide: Planning and Operation of Laboratory HVAC Systems, Second Edition. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA. 2015 or latest edition.

— it is generally not an accepted practice to allow a BSC to positively pressurize an exhaust duct in normal operation. In some cases, however, it may be acceptable for the Type C1 to displace its exhaust air into a failing system for an interval of up to 5 minutes. In order to mitigate the potential risks, before configuring such an installation:

— a risk assessment of the installation should be performed. The risk assessment should include evaluation of any other devices that are connected to the same exhaust system, such as other BSCs or laboratory fume hoods. Pressurizing a duct during an exhaust system failure may add risk with any other devices using the same exhaust system.

— the duct must be verified to meet or exceed Seal Class A, as described in HVAC Air Duct Leakage Test Procedures – 201221.

— if these criterion cannot be met, the Type C1 may be reconfigured to either shut its blowers off within 15 seconds during exhaust system failure or the canopy may be reconfigured to direct exhaust air back into the laboratory during exhaust system failure. Alternatively, the type C1 may be disconnected from the exhaust system if a risk assessment allows.

— the exhaust duct must be placed so it can penetrate ceilings and floors without disturbing other ventilation or plumbing systems.

— the exhaust system must minimize excessive lengths and elbows.

E.3.1.5 Question five: If the exhaust system malfunctions, does the user understand its impact on the BSC’s ability to maintain personnel and environmental protection, i.e. containment?

For a Type A BSC fitted with a properly designed canopy connection, reduction or elimination of the exhaust air should not significantly affect the airflow patterns within the BSC. Personnel and product protection of the BSC will remain unchanged; however, chemical vapors generated in the BSC will be exhausted into the laboratory via the openings or slots in the exhaust canopy.

For a Type B BSC, a significant loss of exhaust airflow will result in an alarm, turning off the cabinet blower(s). This stops the flow of air into the front of the BSC (inflow), negating personnel protection, potentially allowing materials in the work area of the BSC to escape into the laboratory.

Type B BSCs have operational and maintenance issues that must be considered:

— These cabinets exhaust as much as 1200 cubic feet per minute of conditioned room air making them relatively expensive to operate.

— The higher static air pressure required to operate Type B cabinets may also result in additional construction costs associated with heavier gauge ductwork and higher capacity exhaust fan.

For a Type C BSC fitted with a properly designed canopy connection, reduction or elimination of the exhaust air should not significantly affect the airflow patterns within the BSC while its blowers are in operation.

Personnel and product protection of the BSC will remain unchanged, and chemical vapors generated in the BSC will be exhausted either back into the room, or into the exhaust system, depending on the configuration of the canopy.

If a Type C1 BSC directs its exhaust into the room during a system failure, the shutdown time of the BSC blowers can be lengthened from 15 s to up to 5 minutes.

If a Type C1 BSC directs its exhaust into the external exhaust system during a system failure, the default shutdown time of the BSC blowers can be lengthened from 15 s to up to 5 minutes, provided:

— A risk assessment indicates the BSC, the work being done in it, and the exhaust system it is connected to is appropriate; and

— The BSC is connected to an exhaust duct that has been verified to meet or exceed Seal Class A, as described in HVAC Air Duct Leakage Test Procedures – 201221

Table E.1 - Characteristics of type A1 and A2 BSCs

Type A1 (figure E2) Type A2 (figure E2) intended purpose

Routine microbiological work. Work with volatile organic chemicals on the work surface permitted as an adjunct to microbiological research if the BSC is canopy-connected to external ex-haust and permitted by risk analysis.

Routine microbiological work. Work with volatile organic chemicals on the work surface permitted as an adjunct to microbiological research if the BSC is canopy-connected to external ex-haust and permitted by risk analysis.

airflow pattern

Room air is drawn in through the sash opening, protecting the operator.

HEPA- or ULPA- filtered air flows down through the work area, protect-ing the product. Both bodies of air flow through a common plenum to the cabinet blower(s). A portion flows out of the cabinet via an Exhaust HEPA or ULPA filter, and the remainder re-circulates through a Supply HEPA or ULPA filter before flowing down through the work area.

Room air is drawn in through the sash opening, protecting the operator.

HEPA- or ULPA- filtered air flows down through the work area, protect-ing the product. Both bodies of air flow through a common plenum to the cabinet blower(s). A portion flows out of the cabinet via an Exhaust HEPA or ULPA filter, and the remainder re-circulates through a Supply HEPA or ULPA filter before flowing down through the work area.

air recirculation Varies by model Varies by model inflow Minimum 75 ft/min (0.38 m/s) Aver-age

Minimum 100 ft/min (0.51 m/s) Aver-age downflow Varies by model, typically 50-80 ft/min (0.25-0.40 m/s) average

Varies by model, typically 50-80 ft/min (0.25-0.40 m/s) average biological containment

All NSF-Listed BSCs must pass the same Biological Containment Tests.

All NSF-Listed BSCs must pass the same Biological Containment Tests.

exhaust system Canopy connection as needed. Canopy connection as needed.

exhaust system type

Canopy connected Type A BSCs may be ganged into a multiple-cabinet ex-haust system, if all BSCs are bal-anced properly.

Canopy connected Type A BSCs may be ganged into a multiple-cabinet ex-haust system, if all BSCs are bal-anced properly.

exhaust system function

To convey the BSC exhaust air, plus an additional volume required by the canopy through the ductwork.

To convey the BSC exhaust air, plus an additional volume required by the canopy through the ductwork.

exhaust system volume

Greater than Type B1 Less than Type B2.

Greater than Type B1 Less than Type B2.

exhaust system negative static pressure at BSC

Typically 0.7 inches w.g. (170 Pa). Typically 0.7 inches w.g. (170 Pa).

exhaust system reserve capacity

Static pressure requirements will not change as the cabinet filters load.

Static pressure requirements will not change as the cabinet filters load.

Table E.1 - Characteristics of type A1 and A2 BSCs

Type A1 (figure E2) Type A2 (figure E2) cabinet flexibility Can be connected or disconnected from exhaust system as needs change.

Can be connected or disconnected from exhaust system as needs change.

cabinet cost Less than Type B Less than Type B installation cost Much less than Type B if recirculating;

less than Type B if canopy-con-nected.

Much less than Type B if recirculating;

less than Type B if canopy-con-nected.

electrical cost (BSC only) Slightly more than Type B2 Slightly more than Type B2 tempered air loss If recirculating in lab; none. If canopy-connected, typically 75 CFM/foot (7 m3/m) of BSC width or less.

If recirculating in lab; none. If canopy-connected, typically 100 CFM/foot (9 m3/m) of BSC width or less.

Table E.2 - Characteristics of Type B1 and Type B2 BSCs

Type B1 (figure E4) Type B2 (figure E5)

Type B1 cabinets may be used for routine microbiological work. Work with volatile organic chemicals on the work surface permitted as an adjunct to microbiological research if permit-ted by risk analysis. A majority of the downflow air is directly exhausted from the rear portion of the cabinet.

Type B2 cabinets may be used for routine microbiological work. Work with volatile organic chemicals on the work surface permitted as an adjunct to microbiological research if permit-ted by risk analysis. All downflow air is directly exhausted from the work area with no recirculation.

airflow pattern

Room air is drawn in through the sash opening, protecting the operator.

HEPA- or ULPA- filtered air flows down through the work area, protect-ing the product. The room air, and a portion of downflow air in the front of the work area is recirculated through a supply HEPA or ULPA filter before flowing down through the work area.

The air in the rear of the work area flows out of the cabinet via an Ex-haust HEPA or ULPA filter.

Room air is drawn in through the sash opening, protecting the operator.

HEPA- or ULPA-filtered room air flows down through the work area, protecting the product. Both bodies of air are drawn out of the cabinet via an Exhaust HEPA or ULPA filter.

air recirculation Varies by model; less than 50% None inflow Minimum 100 ft/min (0.51 m/s) Aver-age

Minimum 100 ft/min (0.51 m/s) Aver-age downflow Varies by model, typically 50-80 ft/min (0.25-0.40 m/s) average

Varies by model, typically 50-80 ft/min (0.25-0.40 m/s) average biological contain-ment

All NSF-Listed BSCs must pass the same Biological Containment Tests.

All NSF-Listed BSCs must pass the same Biological Containment Tests.

exhaust system Required. Required.

exhaust system type Must have dedicated ductwork and exhaust blower for each BSC.

Must have dedicated ductwork and exhaust blower for each BSC.

Table E.2 - Characteristics of Type B1 and Type B2 BSCs

Type B1 (figure E4) Type B2 (figure E5) exhaust system function

Must pull exhaust air through the Cabinet’s Exhaust HEPA or ULPA fil-ter and then through ductwork.

Must pull exhaust air through the Cabinet’s Exhaust HEPA or ULPA fil-ter and then through ductwork.

exhaust system volume

B1 is approximately 20% less than a Type A.

B2 exhausts 100% or more air than any other BSC Type.

exhaust system negative static pressure at bsc

Typically 0.7 inches w.g. H2O (170 Pa) minimum.

Typically 1.0 to 2.5 inches w.g. (249 to 622 Pa) H2O minimum.

exhaust system reserve capacity

Static pressure requirements may in-crease up to 0.3 inches w.g. H2O (74 Pa) H2O as exhaust HEPA or ULPA filter loads.

Static pressure requirements may in-crease up to 2.5 inches w.g. (622 Pa) as exhaust HEPA or ULPA filter loads.

cabinet flexibility Must be permanently connected to an exhaust system to function properly.

Must be permanently connected to an exhaust system to function properly.

cabinet cost More expensive than Type A More expensive than Type A installation cost More expensive than a canopy con-nected Type A and require a dedi-cated exhaust fan.

Most expensive. Higher exhaust vol-umes require larger ductwork and higher capacity dedicated exhaust fan.

electrical cost (BSC only) Slightly more than a Type B2. Typically lowest of any BSC.

tempered air loss Equal to a canopy connected Type A.

Typically 50-100 CFM/foot (4.6-9.3 m3/m) of BSC width.

Typically 175 CFM/foot (16.3 m3/m) of BSC width.

Table E.3 - Characteristics of Type C1 BSCs

Type C1 (figure E6)

Type C1 cabinets may be used for routine microbiological work.

Work with volatile organic chemicals on the work surface is permitted as an adjunct to microbiological research if the cabinet is connected to an exhaust system, and is acceptable after performing a risk analysis. Typically, a majority of the downflow air is directly exhausted from the center portion of the cabinet.

airflow pattern

Room air is drawn in through the sash opening, protecting the operator. HEPA- or ULPA- filtered air flows down through the work area, protecting the product. The room air, and a portion of the downflow air in the work area is recirculated through a supply HEPA or ULPA filter before flowing down through the work area.

Typically, the air in the center of the work area flows directly out of the cabinet via an Exhaust HEPA or ULPA filter.

air recirculation Varies by model; typically less than 50% inflow Minimum 100 FPM (0.51m/s) Average downflow Varies by model, typically 50-80 FPM (0.25-0.4 m/s) average biological containment All NSF-Listed BSCs must pass the same Biological Containment Tests.

exhaust system Canopy connection as needed. If BSC exhaust is to be directed into the exhaust duct during a system failure, the ductwork must be sealed and tested for leakage.

exhaust system type Canopy connected Type C1 BSCs may be ganged into a multiple-cabinet exhaust system, if all BSCs are balanced properly.

exhaust system function To convey the BSC exhaust air, plus an additional volume required by the canopy through the ductwork.

exhaust system volume Greater than Type B1 Less than Type B2.

exhaust system negative static pressure at bsc Typically 0.25 inches w.g. (62 Pa).

exhaust system reserve capacity Static pressure requirements will not change as the cabinet filters load.

cabinet flexibility Can be connected or disconnected from exhaust system as needs change.

cabinet cost More expensive than Type A; similar to Type B installation cost Much less than Type B if recirculating; less than B1 if connected to a ganged exhaust system; similar to Type B1 if connected to a dedicated system.

electrical cost (BSC only) Similar to a Type A2.

tempered air loss If recirculating in lab; none. If canopy-connected, typically 75 CFM/foot (7 m3/m) of BSC width or less.

E.3.2 BSC width

Having decided which class and type of BSC is the best, the user should now decide on the width of the BSC. When deciding the width, the user should mark out an area of benchtop equal to the inside (work area) dimensions of the model they are interested in. The user(s) should perform several "dry runs" of their procedures in this area. If the user can work in this defined space, than the cabinet is the proper width, if not, the user may want to try working in the dimensions of the next larger model. If the user does decide on a larger model, however, be sure that the BSC can be transported to and installed in the laboratory through the existing freight elevators, hallways and doors. It is important to remember that BSC widths typically refer to the internal work area. The external width of the BSC may be significantly greater than the work area width. The BSC should be installed with at least 6 inches (150 mm) of unobstructed space on each side. For example, a typical BSC with a 4 foot (1219 mm) workspace may have an outside width of 4.5 feet (1372 mm). When 6 inches (150 mm) of space is allowed on each side of the BSC for servicing, the width needed to install the BSC is 5.5 feet (1676 mm).

E.3.3 BSC options

E.3.3.1 Service valves

Service valves allow inert gases, air or vacuum lines to be plumbed into the BSC. Many models allow for the easy installation of these valves in the field, however, it is generally less expensive and easier to have the required number of valves installed when the unit is ordered. Although many users connect natural gas to a service valve in the cabinet, this practice should be avoided if possible, because open flames in a Class II BSC disrupts the airflow, and there is the possibility of a buildup of flammable gas in BSCs that recirculate their air.

E.3.3.2 Electrical outlets

Most BSCs have electrical outlets installed in the work area as standard equipment. Specialized outlets, such as Ground Fault Circuit Interrupters (GFCIs) should be installed and tested by the cabinet manufacturer.

Typically the outlets in the work area are limited in their amperage rating. This is due to the amperage requirements of the BSC's motor, lighting, and other electrical components.

Variations in line voltage from the laboratory wall outlet may affect the cabinet airflows. A voltage regulator may need to be installed in order to reduce the potential of variations in airflows.

E.3.3.3 Ultraviolet lighting

Germicidal (or UV) Lamps are often installed as an adjunct to surface disinfection. UV lighting is not recommended in Biosafety cabinetry. While their usefulness is a subject for debate among users and manufacturers, they should be installed and tested by the manufacturer during assembly of the unit.

E.3.3.4 IV bar

Because intravenous (IV) bars or rods have a significant impact on the airflows in the work area, always use the IV bar recommended by the manufacturer.

E.3.3.5 Base stands

Base Stands or supports shall be considered at the time of specification. Some models of cabinets can weigh up to 900 pounds (408 kg). The BSC must be attached to a manufacturer recommended base stand to support the unit's weight. All base stands have a maximum height specified by the manufacturer to prevent overturning of the BSC; this maximum should never be exceeded.

E.3.3.6 Mobile installations

Mobile Base Stands with and without lift capability have been used when the BSC is operated in multiple locations in the same or adjoining laboratories. Proper cabinet operation should be confirmed by airflow smoke pattern tests at each site of use. If the cabinet is relocated to another facility, or subjected to excessive shock and/or vibration during moving, the BSC should be recertified to ensure it is functioning in a proper manner.

E.4 Site review before BSC purchase

E.4.1 Consultation

Investigators should consult with a biosafety professional and request a risk assessment of the proposed investigation to ensure that an appropriate BSC is used for the work. Purchase of NSF 49 listed Class II biosafety cabinets is recommended, but alternative containment equipment may be suggested for special tasks.

E.4.2 Site assessment

The investigator should thoroughly examine the intended installation site to ensure it will meet the requirements for proper cabinet operation.

E.4.2.1 Location of the BSC

The cabinet should be located away from traffic patterns, doors, fans, ventilation registers, fume hoods and any other air-handling device that could disrupt its airflow patterns. All windows in the room should be closed. Figure E1 shows the preferred location for the cabinet. The BSC should be located at the wall furthest from and facing the entry door. If this is not possible, the BSC should be located on the side wall perpendicular to the hinge side of the door.

E.4.2.2 Clearances

BSCs not connected to an exhaust system should have at least [12 inches (300 mm)]clearance from the filter face and any overhead obstructions when the cabinet is in its final operating position, to allow for testing of the Exhaust HEPA/ULPA filter. At least 12 inches (300 mm) clearance is required if the use of a thermal anemometer exhaust velocity measurement is needed when calculating cabinet inflow velocity.

All BSCs should be placed in a laboratory at a location that provides a minimum of:

— 6 inches (150 mm) from adjacent walls or columns.

— 6 inches (150 mm) between two BSCs.

— 6 inches (150 mm) space between both sides of the cabinet and 6 inches (150 mm) behind the BSC to allow for service operations.

— 40 inches (1020 mm) of open space in front of the BSC

— 60 inches (1520 mm) from opposing walls, bench tops and areas of occasional traffic.

— 20 inches (510 mm) between BSC and bench tops along a perpendicular wall.

— 100 inches (2540 mm) between two BSCs facing each other.

— 60 inches (1520 mm) from behind a doorway.

— 40 inches (1020 mm) from an adjacent doorway swing side.

— 6 inches (150 mm) from an adjacent doorway hinge side.

E.4.2.3 Exhaust requirements

If the BSC is to be connected to an external mechanical exhaust system, first examine the location to ensure that it is compatible with the cabinet’s exhaust outlet. The area directly above the cabinet’s exhaust outlet should be clear of structural elements, water and utility lines, or other fixed obstructions. There should be enough clearance to allow for the passage of a 10 inches (250 mm) or 12 inches (300 mm) diameter duct.

Avoid cabinet locations that require either an elbow directly on top of the cabinet’s exhaust connection or an excessive number of elbows to clear other items.

E.4.2.4 Electrical requirements

The electrical outlet that the BSC plugs into should have a dedicated circuit breaker. This will prevent the accidental shutdown of the cabinet, should another device overload the circuit.

Some larger cabinet models, when operated at 115 V, will require a circuit rated for 20 Amp service. As the electrical plugs and sockets for 115 V, 15 and 20 Amp ratings are different configurations; the user should confirm that the site outlet socket matches the BSC plug.

NOTE — Some cabinets do not operate properly when connected to a ground fault circuit interrupter (GFCI).

Consult with the BSC manufacturer about compatibility of their model with a GFCI outlet, if one is present.

E.4.2.5 Service line requirements

All service lines to the BSC should meet local building codes, and be equipped with an easily accessible external shut-off valve, should disconnection be required.

E.4.2.5.1 Connecting service valves to flammable materials

NOTE — The use of flammable gases or solvents should be avoided in a BSC. Open flames in the cabinet will disrupt the airflow in the cabinet and may damage the HEPA/ULPA filters. Flammable gases or solvents may reach explosive concentrations in recirculating cabinets or ductwork. If the user feels that their procedure requires the use of an open flame or flammable materials they should contact their institution's safety office.

E.4.2.5.2 Connecting service valves to high pressure service

The use of air or gases under high pressure should be avoided as they may seriously disrupt the airflow patterns in the cabinet.

E.4.2.5.3 Connecting service valves to a central (House) vacuum

If service valves are to be connected to a central (House) vacuum source, appropriate devices, such as disinfectant traps and/or in-line filters should be installed to prevent contamination of the vacuum system.

E.4.2.6 Roof exhaust systems

Roof exhaust systems serving biosafety cabinets should have a stack that extends straight upward at least 10 ft (3 m) above the roof surface or have a stack with a smaller diameter trailing end to produce higher velocity flow to avoid re-entrainment by the building, and should be increased in elevation when necessary to avoid the influence of surrounding structures.7 Raincaps or any other structure that deflects the straight upward flow of the discharged air should be avoided. No precipitation can enter the stack when air is being exhausted at normal stack velocities. To take care of precipitation during periods when system is shut off, a 1 inch (25 mm) hole can be drilled in the lowest point of the fan casing and the water allowed to drain onto the roof. It is recommended that roof exhaust fans be energized by direct-connected electric motors to avoid failures caused by slipping and breaking of belts. Another advantage of direct-connected fans is the ability to use the motor non-function to activate an alarm in the laboratory, whereas when a malfunctioning belted fan is employed, the motor can be operating when the fan is idle. A diagram illustrating a recommended roof exhaust facility is shown in Annex E, figure E7 High Velocity Fans.44

7 ASHRAE/AHIA Z9.5

E.4.3 Pre-purchase checklist

The investigator should notify building management to arrange for feasibility assessment of laboratory alterations and BSC location. The investigator and biosafety professional should discuss the following points about the BSC and its delivery:

— ensure all arrangements are planned in advance of the BSCs arrival;

— get a written price quote for the entire package, including the BSC Model number, optional equipment, canopy exhaust connection, etc. Work out the details about shipping and delivery with the manufacturer's representative at the time of purchase;

— determine the costs for shipping and delivery because there may be additional costs depending on the location and level of difficulty of delivery;

— ensure that the sales representative clarifies in writing what is included in "shipping and delivery."

Does it include delivery of the BSC to the receiving dock of the building or to the laboratory? Does it include BSC set-up in the work area, and removal of cartoning/crating materials?

— if not covered in the purchase price, the customer will have to get facility personnel, or hire moving contractors to uncrate and move the BSC;

— ensure the corridor pathways are clear for delivery to the laboratory;

— will the BSC fit through door jams?

— will the BSC travel around sharp, narrow corridors and corners?

— will the elevators in the building accommodate the BSC?

— does the BSC have to be brought up steps?

— the moving contractor should be advised that the BSC shall be lifted onto its stand or leg extensions (working position) with a hydraulic lift; and

— responsibility for removal and proper disposal of all packing materials must be established.

E.5 BSC arrival and certification

E.5.1 When the BSC arrives, inspect it carefully. Compare the invoice with the delivered equipment.

Check for any damage or missing materials and report them immediately to the proper carrier and the BSC supplier regardless of how insignificant they may first appear. Be careful of sharp crating material and let the loading dock personnel help check for damage.

E.5.2 Arrange for certification after the BSC is installed. Building operations personnel may be needed to connect the BSC to laboratory plumbing, electrical, and supply/exhaust air ventilation systems.

E.6 Cleaning and disinfection of BSC work area

E.6.1 Do’s and dont’s of disinfectant efficacy

— Do evaluate the cleaning processes and frequencies for ability to control organisms separately from the disinfectant efficacy study.

— Do design a meaningful study that represents use in the facility.

— Do consider additional studies if quality metrics indicate current agents are no longer controlling microorganisms in the area using prescribed disinfection methods.

— Don’t expect the disinfectant study to replace routine cleaning, disinfection and monitoring programs.

— Don’t rely on disinfectant studies to establish that cleaning frequencies and processes to control organisms are sufficient and acceptable.

— Don’t wait until there is a problem to evaluate the disinfectants being used in the facility.

E.6.3 Surface disinfectants

E.6.3.1 Halogens [Hypochlorous Acid HOCl] – active ingredient

— chlorine bleach oxidizing disinfectant that is sporicidal.

— stainless steel is corroded by chlorine bleach. Sodium hypochlorite must be neutralized with sodium thiosulfate or followed by use of a disinfectant or sterile water.

— 1:5 dilution of CloroxTM with water (10,000 ppm) is needed to inactivate Mycobacteria in sputum)

— 1:100 dilution with water (500 ppm) must be made fresh daily and combined with a nonionic detergent.8

— 1:50 dilution stored at room temperature in a closed plastic container will deteriorate to the equivalent of a 1:100 dilution after one month (Amer. J. Infect. Control 17:1, 1989).

— bleach mixed with acid cleaner produces chlorine gas - 1 ppm TLV.

— bleach mixed with ammonia-containing cleaner produces monochloramine and dichloramine irritants.

E.6.3.2 Chlorine Dioxide

— Tuberculocidal, Bactericidal, Virucidal and Fungicidal.

E.6.3.3 Quaternary ammonium salts

— Each compound exhibits its own antimicrobial characteristics

— Chemical names of quaternary ammonium compounds used in healthcare are alkyl dimethyl benzyl ammonium chloride, alkyl didecyl dimethyl ammonium chloride, and dialkyl dimethyl ammonium chloride.

8 National Institutes of Health Laboratory Safety Monograph: A Supplement to the NIH Guidelines for Recombinant DNA Research. U.S. Department of Health, Education, and Welfare, Public Health Service, National Institutes of Health, July 1978

— Newer quaternary ammonium compounds are referred to as twin-chain or dialkyl quaternaries (e.g.

didecyl dimethyl ammonium bromide and dioctyl dimethyl ammonium bromide)

— A quaternary detergent cleaner is used in maximum containment (BSL-4) facility showers

— Most common institutional disinfectant sold under hundreds of trade names.

— Use dilution ranges from 0.5 - 3% depending on the compound

E.6.3.4 Phenolics

— EPA registered as tuberculocidal

— Many trade names and concentrations of amylphenol and phenyl phenol

— Allergies, skin absorption

— Phenolics are not sporicidal

E.6.3.5 Alcohols

— Flammable

— Alcohols are not sporicidal and must be used as a sterile solution to prevent spread of fungal spores.

— 70% alcohol sprayed on the work surface of an operating biosafety cabinet becomes ineffective within seconds.

— Alcohol attacks acrylic, polypropylene, PVC, and polycarbonate plastics over time.

E.6.3.6 Iodophores

— Often used at a 0.5% concentration

— WescodyneTM diluted 1:213 with water is an effective BSC surface disinfectant

— Non-staining, but will leave a brown residue, nontoxic

— Active against gram negative & gram positive bacteria, viruses, fungi, yeast, M. tuberculosis and many bacterial and fungal spores

— Used on work surfaces, water baths, and incubators

E.6.3.7 Peroxides (stabilized) Hydrogen Peroxide 6-25%

— Often used to sanitize surfaces in the food industry

— Sporicidal agent recommended by cleanroom industry

E.6.3.8 Peracetic Acid

— Sporicidal agent recommended by cleanroom industry

E.7 BSC use practices and procedures

E.7.1 Ergonomics

E.7.1.1 Ergonomics is important for proper BSC use and user health and safety. An evaluation of normal work practices should be performed with each user when working in a BSC.

E.7.1.2 Evaluation criteria should be at a minimum: Proper user posture; Effective work zone layout for work practices; and Correct vision or sightlines

E.7.1.3 User accommodations include a six-way articulating chair with seat and back controls for personalized adjustment to assure proper user posture. Feet should rest on the floor, chair foot support or foot rest. Fully support an individual’s back is fully supported with proper chair adjustments.

E.7.1.4 Forearm/armrest supports are available on some BSC’s to provide forearm support on the work access opening. Periodic mini-breaks during BSC work should be taken by resting your forearm to avoid stress and fatigue.

E.7.1.5 Effective work area layouts will minimize reach to avoid neck and shoulder stress and fatigue.

Rotating tables are available to minimize reach.

E.7.1.6 Always prepare your work procedure to eliminate glare and bright reflections on the sash window and keep the sash sightlines clear to your work zone.

E.7.2 BSC practices

— BSC must be properly certified before use.

— BSC must be positioned in an area with no drafts or foot traffic.

— do not bypass any sash closure or position alarms.

— do not block or restrict any grill(s) or discharge openings.

E.7.3 Do not modify a BSC in a way that may compromise its containment unless approved by appropriate safety personnel for the following modifications:

— installing a water faucet.

— connecting a drain to sewage system.

— installing waste cans under or in the work surface.

— installing other devices (i.e. centrifuge) into the work surface.

— positioning cables, hoses etc. through the work access opening.

E.7.4 BSC techniques

— have proper BSC training including proper aseptic technique before use.

— decontaminate BSC work surface before use.

— ensure that sash is at the proper height depending on BSC model.

— do not use an open flame.

— do not use high pressure gases.

— do not use volatile chemicals without a risk assessment by qualified chemical safety personnel system (Refer to Section E.3.1.3).

— do not place large objects on the BSC work surface.

— do not place fan-cooled devices in the BSC work area.

— minimize room activity

— activity in the room should be held to a minimum. Unnecessary activity may create disruptive air currents as well as interfere with BSC operation. A person walking past the front of a BSC may cause draft velocities up to 175 fpm (89 m/s), which can disrupt the air inside the BSC.

— utilize unidirectional air flow

— keep two important facts in mind: (1) Air supplied to the work area through a supply filter from the top, is contaminant free; and (2) Airborne contamination generated in the work area is controlled by flow of airstreams in a top-to-bottom direction.

— a solid object placed in the sterile air stream will disrupt the air flow and consequently, the capability to control lateral movement of airborne particulates. A cone of turbulence will extend below the object and uniform flow of the air stream will not be regained until for approximately equal to three to six times the size of the object. Within this cone of disturbed air, particles may be carried laterally by multidirectional eddy currents.

— transfer of viable materials and manipulations which may generate aerosols should not be performed above sterile materials.

— employ Aseptic Technique

— do not assume that the BSC will prevent contamination when performing procedures. BSC’s will control airborne contamination of viable agents (i.e., microorganisms), but the BSC will not eliminate contact transmission of contamination. Contamination control procedures such as aseptic technique is required to obtain maximum benefit from the BSC.

— open bottles, tubes or flasks should be kept as parallel as possible to the downflow air to minimize capture of particulates. This precaution is merely good aseptic technique.

— equipment in direct contact with agents must remain in the cabinet until bagged or until surface-decontaminated. Trays of discard pipettes must be covered before removal from the BSC.

— when there is a spill or splatter of agent in the work area, all surfaces and items in the BSC should be surface-decontaminated before materials are removed.

— using natural gas to flame flask or tube necks is not recommended. A gas burner flame in BSC also contributes significantly to the heat build-up inside the BSC and also disrupts the sterile supply air stream. If a procedure demands use of a flame, a Bunsen burner with an on-demand ignition is recommended. Do not use a constant flame gas burner. Bunsen burners must be placed near the rear of the workspace where air turbulence will have a minimal effect.

— a plastic-backed absorbent paper should be placed on the work surface during mixing procedures and replaced whenever significant spills occur and when the work is completed.

— vials should be opened with a tool specifically designed for that purpose. Vials should be vented with a filter needle to eliminate internal pressure or vacuum.

— before opening ampoules, make sure that no liquid remains in the tip of the ampoule. A sterile gauze pad should be wrapped around the neck of the ampoule before it is opened.

— a collection vessel should be available on the work surface for discard of solutions.

E.7.5 BSC start up procedure

— follow manufacturer’s startup procedure. If cabinet alarm condition is present, investigate root cause before continuing.

— inspect air intake grilles for obstructions and foreign materials and remove any obstructions.

Remove all items from the work area.

— adjust view screen to proper height.

— turn on blower and allow five minutes to purge the air.

— wash hands and arms with mild, non-antimicrobial soap for 30 seconds. Put on a rear-fastening, long-sleeved gown with gathered cuffs. Put on a pair (or two pairs) of appropriate long sleeve (11 ½ - 12 inch) gloves (nitrile gloves are recommended for biological work). Consider, when appropriate, disposable sleeve protectors and a second or third pair of appropriate gloves. This will minimize the shedding of skin flora into the work area and also protect hands and arms from viable microbial contamination. Before and after work in a BSC, hands and arms should be washed mild, non-antiseptic soap.

— disinfect the interior surfaces of the BSC by wiping down with appropriate disinfectant for an appropriate contact time. 70% alcohol is not considered an appropriate disinfectant because it has no effect on fungal spores.

— place a plastic-backed pad on the work surface without covering the air intake/exhaust grills. This will prevent spills from hitting the stainless steel surface and creating aerosols.

— put all items for the experiment in the BSC and keep clean items segregated from dirty items by 12 inches (300 mm). Organize the material so that dirty "contaminated" items will not be passed over (cross contaminate) clean items.

— exercise care that no items be placed over the front intake grills. Materials should be arranged so that clean materials are separated from dirty (used) virus materials. Passage of contaminated materials over non-inoculated cultures or clean glassware should be avoided to prevent contamination. Transfer of viable materials should be performed as deeply into the cabinet (away from open face) as possible.

— allow air to stabilize for five minutes before starting work. This will rid the area of all "loose" contamination that may have been introduced with the items.

— work from "clean" to "dirty" areas and work at least six inches (150 mm) back from rear of the front air intake grill.

— move arms in and out of the work access opening perpendicular to the front of the BSC in a slow steady motion to minimize disruption of the front air curtain.

— minimize penetration of the work opening air curtain.

— aminimum number of needed items should be placed into the BSC to prevent overloading. Work should be planned to minimize the number of times an operator's hands and arms must enter and leave the air curtain. Ideally, have everything needed for your procedure placed in the BSC before starting, so that nothing needs to pass in or out through the front air curtain until the procedure is completed. Do not raise your hands inside the BSC above the top level of the sash height. If you raise your hands above the sash height, air may flow up your hands to elbows and possibly out of the BSC.

— know your "safe working area". BSC safe working area is the work tray or depressed area. All work should be performed on or above the work tray. The area on or above and within 6 inches (150 mm) from the rear of the front grill is a non-safe working area.

— this is a general operational guideline to control airborne contaminants of low to moderate risk.9 Procedure protocols defined in terms of the barrier or control concepts unique to BSC’s must be developed for maximum safety and protection.

— for preparation of antineoplastic drugs, the following procedures summarize the OSHA Technical Manual TED 1-0.15A, Section VI, Chapter 2 "Controlling Occupational Exposure to Hazardous…