A Guide to Biosafety & Biological Safety Cabinets
Contents
1. qe oyu Anu bupu 1 10 2 isnjd jauuosiad qel qo sajdwies windas auljaseg qe aysem JO SS DDP PA OUJUOD isnjd Z se Uon qold Ajojesidsay 6 aue ian JNS ed pPaw JO UOHEUIWWe uodap a sem p p u Aue Buluyap jenuew Ajajesoig suolnedaid sdueys subis Bulusem piezeyo SS DE D M isnjd sapped Je3150J01qo nN psepueys pue 5 212244 sjuaby suon pue S A 7 5018 40 AJEWILUNS 1 lqeL Jana4 Kalen HY SIA lquloN uls aulez eloq4 z l uon npold siseryjue ulng IXO2 SNA eydadua sino 1S sISO NDEGNL N SMA g shned H dds ewse doxoy p l uouulps SNUIA S SP VN 11023 snua shned u aulued snon uaqnib evajbaen s l qns sniloeg sajdwexq ES ZS d 6661 Iud uonipI r S6 8 66 DGD uonpollqnd SHH sadIAJasS UEWINH pue y e H unled q S N s nozeroqeT feoip ulolg pue u q esolg UOISSIUSUEJ 10 JSI UMOUN YUM sjuabe 10 suom lul qe payiusuesy josolay aseasip Bulua e ay JO JSU ublu e asod ey sjuabe nox snolabueq s u nb suo le 9 10 SDOL S aney Aew aseasip UOIS SIUSULJ2. A Guide to Biosafety amp Biological Safety Cabinets 0 WORLD CLASS WORLDWIDE Foreword This booklet was developed as a guide to biological safety cabinets and provides basic knowledge of biosafety and biological safety cabinets The information presented is unbiased and generic in nature compiled with help from experienced microbiologists engineers and safety enclosure users BOHAZARDS AND BIOSAFETY LEVELS The word biohazard is a contraction of the words biological and hazard and defined as an infectious agent or part thereof presenting a real or potential risk to the well being of man animals and or plants directly through infection or indirectly through disruption of the environment Biosafety Levels 1 through 4 were established by the Centers for Disease Control CDC and the National Institutes of Health NIH and are combinations of laboratory practices and techniques safety equipment and facilities All of these levels are appropriate for the biohazard posed by the agents used and for the laboratory activity Biosafety Level 1 Practices safety equipment and facilities appropriate for work with defined and characterized strains of viable micro organisms not known to cause disease in healthy adult humans The laboratory is not necessarily separated from the general traffic patterns in the building Work is generally conducted on open bench tops using standard microbiological practices Special containm
3. negative pressure ventilation rate air flow smoke pattern and alarms and interlocks Optional tests for electrical leaks lighting intensity ultraviolet light intensity noise level and vibration may also be conducted Special training skills and equipment are required to perform these tests and it is highly recommended that they are undertaken by a qualified professional 9 Cleaning and Disinfection All items within BSCs including equipment should be surface decontaminated and removed from the cabinet when work is completed since residual culture media may provide an opportunity for microbial growth The interior surfaces of BSCs should be decontaminated before and after each use The work surfaces and interior walls should be wiped with a disinfectant that will kill any microorganisms that might be found inside the cabinet At the end of the work day the final surface decontamination should include a wipe down of the work surface the sides back and interior of the glass A solution of bleach or 70 alcohol should be used where effective for target organisms A second wiping with sterile water is needed when a corrosive disinfectant such as bleach is used It is recommended that the cabinet be left running If not it should be run for 5 min in order to purge the atmosphere inside before it is switched off A Guide to Biosafety amp Biological Safety Cabinets Proper Selection Installation amp Safe Use of BSCs 10 Decontamin
4. opening Minimize external airflow disturbances Work from clean to dirty Biohazard collection bags should be placed inside the cabinet instead of outside e Use absorbent pads on the work surface where appropriate to minimize splatter and aerosol generation in case of a spillage Surface decontaminate before removing potentially contaminated items from the interior e Place aerosol generating instruments as far in to the interior of the cabinet as possible Clean materials should be at least 150 mm away from aerosol generating objects to minimize the chance for cross contamination e Hold lids covers above dishes sample plates in order to prevent impingement of downward air Do not use a gas flame whenever possible as it interferes with airflow e Put air turbulence generating equipment such as centrifuge blender or sonicator in the back 1 3 of the cabinet A Guide to Biosafety amp Biological Safety Cabinets Proper Selection Installation amp Safe Use of BSCs 3 Bunsen Burner Burners can cause an outflow of air from inside the cabinet that can endanger the operator On Class Il cabinets protection against cross contamination may also be compromised There have been incidents where the sash of a recirculating Class Il safety cabinet was closed while the burner was still on causing heat build up in the cabinet that damaged the filters Bunsen Burner Safety An electronic burner which automatica
5. work surface and any equipment in the cabinet with a disinfectant soaked paper towel Discard contaminated disposable materials using appropriate biohazardous waste disposal procedures e g autoclave or BFI Place contaminated reusable items in biohazard bags autoclavable pans with lids or wrap in newspaper before autoclaving and cleanup Expose non autoclavable materials to disinfectant 20 minute contact time before removal from the BSC Remove protective clothing used during cleanup and place in a biohazard bag for autoclaving Run cabinet 10 minutes after cleanup before resuming work or turning cabinet off Inside The Lab Outside The BSC Call the biosafety office if the material is BSL 2 or greater containment Clear area of all personnel Wait at least 15 minutes for aerosol to settle before entering spill area Remove any contaminated clothing and place in biohazard bag to be autoclaved Put on a disposable gown safety glasses and gloves Initiate cleanup with disinfectant as follows il nu S U Place dry paper towel on spill to absorb liquids then layer a second set of disinfectant soaked paper towels over the spill Encircle the spill with additional disinfectant being careful to minimize aerosolization while assuring adequate contact Decontaminate all items within spill the area Allow 20 minutes contact time to ensure germicidal action of disinfectant Wipe equipment with appr
6. a location remote from traffic and potentially disturbing air currents Whenever possible a 30 cm clearance should be provided behind and on each side of the cabinet to allow easy access for maintenance A clearance of 30 35 cm above the cabinet may be required to provide for accurate air velocity measurement across the exhaust filter and for exhaust filter changes 2 Operators If BSCs are not used properly their protective benefits may be greatly diminished Operators need to be careful to maintain the integrity of the front opening air inflow when moving their arms into and out of cabinets Arms should be moved in and out slowly perpendicular to the front opening Manipulations of materials within BSCs should be delayed for about 1 min after placing hands and arms inside to allow the cabinet to adjust and to air sweep the surface of the hands and arms The number of movements across the front opening should also be minimized by placing all necessary items into the cabinet before beginning manipulations Biological Safety Cabinet Return Air Grille Personnel Traffic BSC l Barrier Airflovv Air Inlet 1 Cabinet is quite appropriately located with respect to avoidance of excessive air movements from surrounding areas 2 Cabinet is too close to the doorway and its airflow could be influenced by the air inlet too 3 The airflow of cabinet 69 could also be influenced by the air inlet 4 Cabinet is too close to
7. and are all suitable for work with agents assigned to biosafety levels 1 2 and 3 A Guide to Biosafety amp Biological Safety Cabinets Biological Safety Cabinets Class Il Type A A1 A2 Biological Safety Cabinets The Class Il Type A biological safety cabinet is the most common Class Il cabinet It is also the most common safety cabinet of all the different types available It has a common plenum from which 30 of air is exhausted and 70 re circulated to the work area as the downflow Type A cabinets exhaust air directly back to the laboratory and they may contain positive pressure contaminated plenums When toxic chemicals must be employed as an adjunct to microbiological processes these cabinets should not be used Exhaust HEPA filtration only removes airborne aerosols including biohazards and not chemical fumes The Class II Type A1 has the positively pressurized contaminated plenum bordering the ambient environment and therefore is less safe than the Class II Type A2 that has a negative pressure surrounding the positively pressurized contaminated plenum In case there is a leakage on the positive plenum the leaking aerosol will be pulled by the negative pressure back to the positive plenum and it will not leak out Because of the safety issue the Type A1 design is now considered obsolete In the A2 cabinet about 70 of air from the positive plenum is recirculated as downflow and the remaining 30 is discharged to the lab thro
8. 05 10 enu od ul sjuabe JO snou bipul insodx uesqw w snoonw uons bul Antu snoaue zndied spyezey Hewd SP S p uewny YUM 0055 sunpe Zu e q ul aseasip sne u sisuoo o umouy JON s u by snon ul Ayayesoig A Guide to Biosafety amp Biological Safety Cabinets Biohazards and Biosafety Levels II BIOLOGICAL SAFETY CABINETS The terms biological safety cabinet and biosafety cabinet have been widely used to describe a variety of containment devices equipped with HEPA filter s designed to provide personnel or both personnel and product protection from biohazardous materials The terms should only be applied to those devices that meet the requirements of Class Il or Ill specifications based on their construction airflow velocities and patterns and their exhaust systems Major International Standards for Biological Safety Cabinets e American Standard NSF 49 e European Standard EN 12469 e Australian Standard AS 2252 e Japanese Standard JIS K 3800 Table 2 Biological Safety Cabinet Classes Source Laboratory Biosafety Manual Second Edition revised Interim guidelines World Health Organization p32 Inflow Class Velocity 5 Air Exhaust Control Plenum Exhaust Biosafety m s Air Surrounded by Alternatives Level 5 7 0 100 Outside Air 177 f 1 2 amp 3 Type A1 70 Cuse Alr Hier oe 0285 Type A2 7 70 30 Negative Plenum 17 1 283 T
9. 1 14 ESCO C VVORLD GLASS WORLDWIDE pue jed1HojoiqosI ul Ajyayesolg ul p uinno se sjualuasinbal euonppy Sul s s pue ulnn eA 3sneux iddns uoz p lefosi JO Hulpjing ayesedas isnjd 4016840061 O Ul MOLH E AD D N ou Jie 15 ss oop JOOp Hulsop jjas SJOPLUOD 55922 WO E lS Ud snd Z ajqeyiene 01 isnjd Juis do u u q u do 13 somes 1115 jauuossad ainssaud aniyisod payddns uie Apoq n YUM uoneuiqwo l 5266 0 10 11556 2 l papnpuo sainpadoud SG LM Q Alu Lg p p u se uon old Alozesdsad S Aol5 Buiyzop qel n old ieuosi q sjuabe Jo suoneyndiueul uado JE 40 p sn sadiAap JUBWU e UOD jerIsAyd Jay O 10 5268 JO sse D S4 LM Q Aled p p u se uola od E S AO1 S EO2 qel ieuosi q SIEH PUL 6 yo 5 05 s ysejds asned yey sjuabe yo suojejndiuew e 10 pasn sadiAap JUawUIe UOD jediskyd 1 470 10 5266 sse D SG LLEQ AleWLd pauinbay UON ER Arewtid A3 es qe wou 1ix UO payeulwe Uodap jenazew V 4X9 UO JAMOUS
10. ation BSCs must be decontaminated before filter changes and before being moved The most common decontamination method is by fumigation with formaldehyde gas In some European country where formaldehyde is banned decontamination can be done using chlorine dioxide or hydrogen peroxide STERIS and BIOQUELL method BSC decontamina tion should be performed by a qualified professional 11 Personal Protective Equipment Personal protective clothing should be worn whenever using a BSC Laboratory coats are acceptable for work being performed at Biosafety Levels 1 and 2 A solid front back closing laboratory gown provides better protection and should be used at Biosafety Levels 3 and 4 except for suit laboratories Gloves should be pulled over the wrists of the gown rather than worn inside Elasticized sleeves can be worn to protect the investigator s wrists Masks and safety glasses may be required for some procedures 12 Alarms BSCs can be equipped with one of two kinds of alarm Sash alarms are found only on cabinets with sliding sashes The alarm signifies that the operator has moved the sash to an improper position Corrective action for this type of alarm is returning the sash to the proper position Airflow alarms indicate a disruption in the cabinet s normal airflow pattern This represents an immediate danger to the operator or product When an airflow alarm sounds work should cease immediately and the laboratory supervisor should be notif
11. disposable dry type filter constructed of borosilicate microfibers cast into a thin sheet much like a piece of paper HEPA High Efficiency Particulate Air Modern American convention HEPA 99 99 at 0 3 microns e ULPA Ultra Low Penetration Air Modern American convention ULPA 99 999 at 0 12 microns HEPA ULPA Filter Construction 10 Fig 5 Separator Type Fig 6 Separatorless Type HEPA ULPA filters are designed to remove a broad range of airborne contaminants including Fine dust Smoke Bacteria typical size 500 to 0 3 microns Soot e Pollen e Radioactive particles Impurity ion gt can affect Integrated Circuit speed A Guide to Biosafety amp Biological Safety Cabinets Biological Safety Cabinets 11 PROPER SELECTION INSTALLATION amp SAFE USE OF BSCS A Selection of A Biological Safety Cabinet A BSC should be selected primarily in accordance with the type of protection needed product protection personnel protection against Risk Group 1 4 microorganisms personnel protection against exposure to radionuclides and volatile toxic chemicals or a combination of these Table 3 shows which BSCs are recommended for each type of protection Table 3 Biological Safety Cabinet Selection Type of protection BSC Selection Personnel Protection microorganisms in Risk g Class Class II Class Ill Groups 1 3 Personnel Protection microorganisms in Risk Class 111 Grou
12. e It has a common plenum from which 70 of air is exhausted and 30 re circulated to the work area as the downflow Type B1 cabinets also have a dedicated exhaust feature that eliminates re circulation when work is performed towards the back within the interior of the cabinet Toxic chemicals employed as an adjunct to microbiological processes should only be employed if they do not interfere with work when re circulated in the downflow Class II Type B2 Biological Safety Cabinets In the Class Type B2 cabinet all inflow and downflow air is exhausted after HEPA filtration to the external environment without recirculation within the cabinet Type B2 cabinets are suitable for work with toxic chemicals employed as an adjunct to microbiological processes under all circumstances since no re circulation occurs In theory Type B2 cabinets may be considered to be the safest of all Class II biological safety cabinets since the total exhaust feature acts as a fail safe in the event that the downflow and or exhaust HEPA filtration systems cease to function normally However Class Type B2 cabinets are in practice difficult to install balance and maintain mer 2 q A Fig 2 Class Type B2 A Guide to Biosafety amp Biological Safety Cabinets Biological Safety Cabinets Class III Biological Safety Cabinets The Class Ill biological safety cabinet provides an absolute level of safety which cannot be attained with Clas
13. e collection tray should not be placed outside the cabinet The frequent in and out movement needed to use these containers is disruptive to the integrity of the cabinets air barrier and can compromise both personnel and product protection 4 Operation and Maintenance Most BSCs are designed to permit operation 24 hr day and investigators find that continuous operation helps to control the levels of dust and particulate materials in the laboratory Class Type A1 and Class Il Type A2 BSCs exhausting to the room or connected by thimble connections to dedicated exhaust ducts can be turned off when not in use Other types such as Class Type B1 and Class Il Type B2 BSCs which have hard duct installations must have air flow through them at all times to help maintain room air balance Cabinets should be turned on at least 5 min before beginning work and after completion of work to allow the cabinet to purge i e to allow time for contaminated air to be removed from the cabinet environment All repairs made on BSCs should be made by a qualified technician Any malfunction in the operation of the BSC should be reported and repaired before the BSC is used again 5 Ultraviolet Lights Ultraviolet lights are not required in BSCs If they are used they must be cleaned weekly to remove any dust and dirt that may block the germicidal effectiveness of the light Ultraviolet light intensity should be checked when the cabinet is recertified to en
14. ent equipment or facility design is neither required nor generally used Laboratory personnel have specific training in the procedures conducted in the laboratory and are supervised by a scientist with general training in microbiology or a related science A biological safety cabinet is generally not required for work involving these agents Biosafety Level 2 Practices safety equipment and facilities appropriate for work done with a broad spectrum of indigenous moderate risk agents present in the community and associated with human disease in varying severity It differs from biosafety level 1 in that a laboratory personnel have specific training in handling pathogenic agents and are directed by competent scientists b access to the laboratory is limited when work is being conducted c extreme precautions are taken with contaminated sharp items and d certain procedures in which infectious aerosols or splashes may be created are conducted in biological safety cabinets or other physical containment equipment A Class or Class Il biological safety cabinet is highly recommended for work involving these agents A Guide to Biosafety amp Biological Safety Cabinets Biohazards and Biosafety Levels Biosafety Level 3 Practices safety equipment and facilities appropriate for work done with indigenous or exotic agents with a potential for respiratory transmission which may cause serious and potentially lethal infection More emphasis is p
15. er 8 Service Manual Labculture Cass II Type A2 Biohazard Safety Cabinet ESCO Micro Pte Ltd Biosafety in Microbiological and Biomedical Laboratories BMBL 4th Edition Office of Health and Safety OHS Centers for Disease Control and Prevention CDC US Department of Health Laboratory Biosafety Manual second Edition revised Interim guidelines World Health Organization UCSD Biosafety Handbook UCSD EH amp S Research Community for Biosafety 1996 UCSD Biosafety Handbook UCSD EH8S Biosafety Team 1996 THE UNIVERSITY OF CALIFORNIA USA ESCO o xKX x CnoCUuv VVORLD GLASS WORLDWIDE Since 1978 Esco has emerged as a leader in the development of controlled environment laboratory and cleanroom equipment solutions Products sold in more than 100 countries include biological safety cabinets fume hoods ductless fume hoods laminar flow clean benches animal containment workstations cytotoxic cabinets hospital pharmacy isolators and PCR cabinets and instrumentation With the most extensive product line in the industry Esco has passed more tests in more languages for more certifications throughout more countries than any biosafety cabinet manufacturer in the world Esco remains dedicated to delivering innovative solutions for the clinical life science research and industrial laboratory community www escoglobal com Biological Safety Cabinets and Laminar Flow Laboratory Fume H
16. ied Manufacturers instruction manuals should provide further details Training in the use of BSCs should cover this aspect 13 Supplementary Information Selecting the correct type of BSC installing it using it properly and annually certifying its operation are complex processes It is highly recommended that they proceed under the supervision of a well trained and experienced biosafety professional The professional should be highly familiar with the relevant literature listed in the References section and should have been trained on all aspects of BSCs Operators should receive formal training in the operation and use of BSCs ESCO 15 C VVORLD GLASS WORLDWIDE 16 C Safe Use of Biological Safety Cabinets 1 Start Up Wear gloves for hand protection Load the cabinet with all items required prior to starting work and surface decontaminate Surface decontaminate the work surface side walls and inner back walls Allow the work zone air to purge for a few minutes before commencing work Do not overcrowd the work zone Close the drain valve before operation 2 Operation Do not obstruct the front or back air grilles Work as far in to the cabinet as possible Minimize arm movement make slow movements to avoid disrupting cabinet airflow When removing arms from cabinet be sure to surface decontaminate first and move arms out slowly of the cabinet in direction perpendicular to plane of work zone
17. laced on primary and secondary barriers to protect personnel in the contagious area the community and the environment from exposure to potentially infectious aerosols A Class or Class II biological safety cabinet is required for work involving these agents Biosafety Level 4 Practices safety equipment and facilities appropriate for work done with dangerous and exotic agents which pose a high risk of life threatening disease May be transmitted via the aerosol route and for which there is no available vaccine or therapy Members of the laboratory staff have specific and thorough training in handling extremely hazardous infectious agents and they understand the primary and secondary containment functions of the standard and special practices the containment equipment and the laboratory design characteristics They are supervised by competent scientists who are trained and experienced in working with these agents Access to the laboratory is strictly controlled by the laboratory director The facility is either in a separate building or in a controlled area within a building which is completely isolated from all other areas of the building A specific facility operations manual is prepared or adopted A Class Ill biological safety cabinet is required for work involving these agents From Biosafety in Microbiology and Biomedical Laboratories U S Department of Health and Human Services HHS publication CDC 99 8395 4th Edition April 1999 p 1
18. lly reduces the gas supply to maintain a smaller flame during periods of non use Anemergency shut off valve should be easily accessible near to the cabinet in case of an emergency e The burner should be placed as far into the cabinet working space as possible to minimize its effect on cabinet performance A solenoid valve can be interlocked with the gas supply to automatically shut off the burner 4 Shut Down Note operate the cabinet continuously whenever possible to maximize protection surface decontaminate all items V7 e Seal biohazard bags if used e Surface decontaminate the cabinet innerside walls back wall work surface drain pan and the inner side of the sliding sash hinged window Allow work zone air to purge e When available install front closure or close sash and activate UV lamp if desired 5 User Maintenance e Pre filter replacements once every 3 months e UV lamp replacement once a year e Operational verification if appropriate e g alarm checks basic airflow measurements etc ESCO C VVORLD GLASS WORLDWIDE me IV BIOHAZARD SPILLS 8 CLEANUP PROCEDURES Inside The BSC Wait at least five minutes to allow the BSC to contain aerosols Wear lab coat safety glasses and gloves during cleanup Allow cabinet to run during cleanup Apply disinfectant and allow a minimum of 20 minutes contact time Wipe up spillage with disposable disinfectant soaked paper towel Wipe the walls
19. oods Laboratory Ovens Laboratory Incubators e PCR Thermal Cyclers e Microplate Shaker Incubators Ultraflow Freezers 284 OW8359R_V3_5K_02 09 WORLD CLASS WORLDWIDE Esco Technologies Inc 2940 Turnpike Drive Units 15 16 Hatboro PA 19040 USA Toll Free USA and Canada 877 479 ESCO Tel 215 441 9661 Fax 215 441 9660 us escoglobal com usa escoglobal com Esco Micro Pte Ltd e 21 Changi South Street 1 Singapore 486 777 Tel 65 6542 0833 Fax 65 6542 6920 mail escoglobal com www escoglobal com Esco Global Offices Kuala Lumpur Malaysia Leiden The Netherlands Manama Bahrain Mumbai India Philadelphia USA Salisbury UK Shanghai China Singapore 2009 Esco Micro Pte Ltd Specifications Subject to Change ESI Ce stil E m o ik ek 7421 Exo Mir Ptelts PT Esco inan Indonesia Cort No 651233 Cert No 65133371 gan 2 L VE SUPPORT
20. opriate disinfectant Discard contaminated disposable materials using appropriate biohazardous waste dis posal procedures e g autoclave or BFI Disinfect reusable items A Guide to Biosafety amp Biological Safety Cabinets Biohazard Spills amp Cleanup Procedures C Inside The Centrifuge e Clear area of all personnel e Wait 30 minutes for aerosol to settle before attempting to clean up spill Wear a lab coat safety glasses and gloves during cleanup e Remove rotors and buckets to nearest biological safety cabinet for cleanup e Thoroughly disinfect inside of centrifuge e Discard contaminated disposable materials using appropriate biohazardous waste disposal procedures e g autoclave or BFI D Outside The Lab In Transit Transport labelled biohazardous material in an unbreakable well sealed primary container placed inside of a second unbreakable lidded container cooler plastic pan or pail labelled with the biohazard symbol e Should a spill occur in a public area do not attempt to clean it up without appropriate personal protective equipment e Secure the area keeping all people well clear of the spill e Call professional help to assist in cleanup e Stand by during spill response and cleanup activity and provide assistance only as 19 requested or as necessary From UCSD Biosafety Handbook UCSD EH amp S Biosafety Team 1996 THE UNIVERSITY OF CALIFORNIA USA p95 97 V REFERENCES Us
21. ps 4 glove box laboratory Personnel Protection microorganisms in Risk Class Class Il Groups 4 suit laboratory Product Protection Class II Class III only if laminar flow included Volatile radionuclide chemical protection minute amounts Class II Type B1 Class Il Type A2 vented to the outside Volatile radionuclide chemical protection Class Class Type B2 Class 111 Source Laboratory Biosafety Manual Second Edition revised Interim guidelines World Health Organization p29 Volatile or toxic chemicals should not be used in BSCs that recirculate exhaust air to the room i e Class that are not ducted to building exhaust systems or Class Il Type A1 or Class Type A2 cabinets Class Type B1 cabinets are acceptable for work with minute amounts of volatile chemicals and radionuclides A Class II Type B2 cabinet also called a total exhaust cabinet is necessary when significant amounts of radionuclides and volatile chemicals are expected to be used ESCO 11 C VVORLD GLASS VVORLDVVIDE 12 B Using Biological Safety Cabinets In The Laboratory 1 Location The velocity of air flowing through the front opening into a BSC is about 0 45 m s At this velocity the integrity of the directional air inflow is fragile and can be easily disrupted by air currents generated by people walking close to the BSC open windows air supply registers and opening and shutting doors Ideally BSCs should be situated in
22. s and Class II cabinets All Class III cabinets are usually of welded metal construction and are designed to be gas tight Work is performed through glove ports in the front of the cabinet During routine operation negative pressure relative to the ambient environment is maintained within the cabinet This provides an additional fail safe mechanism in case physical containment is compromised On all Class 111 cabinets a supply of HEPA filtered air provides product protection and prevents cross contamination of samples Exhaust air is usually HEPA filtered and incinerated Alternatively double HEPA filtration with two filters in series may be utilized Materials are transferred into the cabinet using a pass through unit installed at the side of the work area Class Ill cabinets usually exhaust air back to the laboratory however air may also be exhausted via a dedicated ductwork system to the external environment When a dedicated ductwork system is employed they are also suitable for work employing toxic chemicals as an adjunct to microbiological processes All Class Ill biological safety cabinets are suitable for work with microbiological agents assigned to biosafety levels 1 2 3 and 4 They are frequently specified for work involving the most lethal biological hazards Fig 3 Class Ill BSC ESCO C VVORLD GLASS WORLDWIDE HEPA amp ULPA Filter The HEPA filter is the heart of the biological safety cabinet The HEPA filter is a
23. sure that light emission is appropriate Ultraviolet lights must be turned off while the room is occupied to protect eyes and skin from inadvertent exposure ESCO 13 C VVORLD GLASS WORLDWIDE 14 6 Open Flames Open flames should be avoided in the near microbe free environment created inside the BSC They disrupt the air flow patterns and can be dangerous when volatile flammable substances are also used To sterilize bacteriological loops micro burners or electric furnaces are available and are preferable to open flames 7 Spills A copy of the laboratory s protocol for handling spills should be posted read and understood by everyone who uses the laboratory When a spill of biohazardous material occurs within a BSC cleanup should begin immediately while the cabinet continues to operate An effective disinfectant should be used and applied in a manner that minimizes the generation of aerosols All materials that come into contact with the spilled agent should be disinfected and or autoclaved 8 Annual Certification The functional operation and integrity of each BSC should be certified to national or international performance standards at the time of installation and regularly thereafter by qualified technicians according to the manufacturer s instructions Evaluation of the effectiveness of cabinet containment should include tests for cabinet integrity HEPA filter leaks downflow velocity profile face velocity
24. the doorway 5 Cabinet is suitably located provided that the adjacent return air grille does not influence cabinet airflow Figure 7 illustrates various possible influences that can be induced by a rooms design and ventilation system on the cabinets airflow Please note that Figure 7 does not depict any typical installation In fact it is NOT recommended that so many cabinets be placed in a small room or in close Fig 7 A Typical Class II Cabinet Installation proximity to each other A Guide to Biosafety amp Biological Safety Cabinets Proper Selection Installation 8 Safe Use of BSCs 3 Material Placement The front intake grill of Class Il BSCs must not be blocked with paper equipment or other items Materials to be placed inside the cabinet should be surface decontaminated with 70 alcohol Work may be performed on disinfectant soaked absorbent towels to capture splatters and splashes All materials should be placed as far back in the cabinet towards the rear edge of the work surface as practical without blocking the rear grill Aerosol generating equipment e g mixers centrifuges etc should be placed towards the rear of the cabinet Bulky items such as biohazard bags discard pipette trays and suction collection flasks should be placed to one side of the interior of the cabinet Active work should flow from clean to contaminated areas across the work surface The autoclavable biohazard collection bag and pipett
25. ugh the exhaust filter vest Fig 1 Class Il Type A2 BSC Class II Type B Biological Safety Cabinets The main difference between Type A and Type B cabinet is Type B cabinets must be operated with an external blower and it exhausts air to the external environment via a dedicated ductwork system Without the external blower the cabinets internal blower will blow the air and microbiological agents inside the work zone through the front opening towards the operators face creating a dangerous situation This cabinet is not self balancing in the sense that its own blower can only create downflow and the cabinet relies on the external blower to create inflow ESCO WORLD CLASS WORLDWIDE On all Type B cabinets environmental protection may be enhanced by installing a scrubbing system between the exhaust of the cabinet and the final exhaust point outside the building to neutralize the chemical fumes present in exhaust air Although Type B cabinets are commonly used when chemicals are involved in your work processes they theoretically provide an increased level of safety as compared to other Type A cabinets By exhausting air directly to the external environment they provide an additional fail safe in the event that the regular exhaust HEPA filtration ceases to function Class II Type B1 Biological Safety Cabinets The Class II Type B1 biological safety cabinet was originally specified by the American National Cancer Institut
26. ward air moving into the cabinet This is known as the inflow and it prevents the aerosol generated during microbiological manipulations to escape through the front opening However unlike Class cabinets the inflow on Class II cabinets flows through the front inlet grille near the operator None of the unfiltered inflow air enters the work zone of the cabinet so the product inside the work zone is not contaminated by the outside air A feature unique to Class II cabinets is a vertical laminar unidirectional HEPA filtered air stream that descends downward from the interior of the cabinet This continuously flushes the cabinet interior of airborne contaminants and protects samples being handled within the cabinet from contamination and is known as the downflow The differences between the various Class II cabinets available lie primarily with the percentage of air exhausted to that of air re circulated from the common air plenum In addition different Class Il cabinets have different means of cabinet exhaust Some cabinets may exhaust air directly back to the laboratory while others may exhaust air through a dedicated ductwork system to the external environment Despite these differences all Class Il cabinets like Class cabinets protect both the operator and environment from exposure to biohazards In addition Class II cabinets also protect product samples from contamination during microbiological manipulations within the cabinet interior
27. ype B1 50 30 70 Negative Plenum Hard duct only 1 283 Type B2 5 0 100 Negative Plenum Hard duct only 1 28 3 2 0 100 Negative Plenum b 4 1 2 384 Pressure differential between chamber and environment ESCO C VVORLD GLASS WORLDWIDE Class Biological Safety Cabinets The Class cabinet has the most basic and rudimentary design of all biological safety cabinetry available today A stream of inward air moving into the cabinet contains aerosols generated during microbiological manipulations It then passes through a filtration system that traps all airborne particles and contaminants Finally clean decontaminated air is exhausted from the cabinet The filtration system usually consists of a pre filter and a HEPA High Efficiency Particulate Air filter Although the Class cabinet protects the operator and the environment from exposure to biohazards it does not prevent samples being handled in the cabinet from coming into contact with airborne contaminants that may be present in room air Naturally there is a possibility of cross contamination that may affect experimental consistency Consequently the scope and application of Class cabinets is limited and it is largely considered obsolete All Class biological safety cabinets are suitable for work with microbiological agents assigned to biosafety levels 1 2 and 3 Class II Biological Safety Cabinets Like Class safety cabinets Class Il cabinets have a stream of in
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