ent.
Primary Containment for Biohazards: Selection, Installation and Use of Biological Safety Cabinets 3rd Edition
Primary Containment for Biohazards:
Selection, Installation and Use
of Biological Safety Cabinets
3rd Edition
DEPARTMENT OF HEALTH & HUMAN SERVICES
Centers for Disease Control and Prevention
and
National Institutes of Health
September 2007
iii
EDITORS:
L. Casey Chosewood, MD
Director, Office of Health and Safety
Centers for Disease Control and Prevention
Atlanta, GA 30333

Deborah E. Wilson, DrPH, CBSP
Director, Division of Occupational Health and Safety
Office of Research Services
National Institutes of Health
Bethesda, MD 20892

CONTRIBUTORS:
Centers for Disease Control and Prevention, Office of Health and Safety
Martin Sanders, PhD CBSP
William Howard, MS
Shanna Nesby, DVM
Robin Weyant, PhD
Henry Mathews, PhD
Jonathan Richmond, PhD
Mike Weathers
National Institutes of Health, Division of Occupational Health and Safety
Edward F. Sorensen III
Mark Gibson, CIH
Doris McKinney
OTHER CONTRIBUTORS:
Lee Alderman
Emory University, Atlanta, GA
Richard Green
Georgia Public Health Lab, Decatur, GA
Gregg Schuiling
NSF International, Ann Arbor, MI
Jack Wunder
University of Wisconsin, Madison, WI
Dennis Eagleson
The Baker Company, Sanford, ME
Steven Kridel
Duke University, Durham, NC
William Peters
Nuaire, Plymouth, MN
The editors would like to extend special thanks to David G. Stuart, PhD, The Baker
Company, Sanford, ME for his extensive contributions to this work. iv v
TABLE OF CONTENTS
Section l
Introduction ....................................................................... 1
Section ll
The High Efficiency Particulate Air (HEPA) Filter and
the Development of Biological Containment Devices .... 3
HEPA Filters ...................................................................... 4
Section lll
Biological Safety Cabinets ................................................ 6
The Class l BSC ............................................................ 6
The Class ll BSC ........................................................... 7
The Class lll BSC ......................................................... 12
Horizontal Laminar Flow Clean Bench ......................... 13
Vertical Laminar Flow Clean Bench ............................. 14
Section lV
Laboratory Hazards and Risk Assessment ..................... 15
Chemicals in BSCs ...................................................... 15
Radiological Hazards in the BSC ................................ 17
Risk Assessment ......................................................... 17
Section V
BSC Use by the Investigator:
Work Practices and Procedures .................................. 18
Preparing for Work Within a Class II BSC ................... 18
Material Placement Inside the BSC ............................. 20
Operations Within a Class II BSC ................................ 21
Laboratory Hazards ..................................................... 21
Decontamination .......................................................... 23
Cabinet Surface Disinfection ....................................... 23
Gas Decontamination .................................................. 24
Section VI
Facility and Engineering Requirements .......................... 25
Secondary Barriers ...................................................... 25
Building Exhaust .......................................................... 25
Utility Services ............................................................. 26
Ultraviolet Lamps ......................................................... 26
BSC Placement ........................................................... 26
HEPA Filters ................................................................ 28 vi
Section VII
Certification of Biological Safety Cabinets ...................... 30

Development of Containment Standards ................. 30

Performance Testing BSCs in the Field .................... 32

A. Downflow Velocity and Volume Test .................... 32

B. Inflow Velocity Test ............................................... 32

C. Airflow Smoke Patterns Tests .............................. 32

D. HEPA Filter Leak Test .......................................... 33

E. Cabinet Leak Test ................................................ 33

F. Electrical Leakage and Ground Circuit

Resistance and Polarity Tests .............................. 33

G. Lighting Intensity Test .......................................... 34

H. Vibration Test ....................................................... 34

I. Noise Level Test ................................................... 34

J. UV Lamp Test ....................................................... 34
References ...............................................................50 vii
TABLES
Table 1. Selection of a Safety Cabinet Through

Risk Assessment .................................................35
Table 2. Comparison of Biosafety Cabinet

Characteristics ....................................................36
Table 3. Performance Tests to be Applied to

the Three Classes of Biological

Safety Cabinets ..................................................37
Table 4. References for Applicable

Containment Tests ..............................................38 viii
FIgURES
Figure 1. ............................................................HEPA Filters
Figure 2. ..................................................... The Class I BSC
Figure 3. ....................................... The Class II, Type A BSC
Figure 4. ............................................................Thimble Unit
Figure 5A. ........ The Class II, Type B1 BSC (classic design)
Figure 5B. .... The Class I, Type B1 BSC (bench top design)
Figure 6. .....................................The Class II, Type B2 BSC
Figure 7. ..... The tabletop model of a Class II, Type B3 BSC
Figure 8. ................................................... The Class III BSC
Figure 9A. ...........The horizontal laminar flow clean bench
Figure 9B. .............. The vertical laminar flow clean bench
Figure 10. .. A modified containment cabinet or Class I BSC
Figure 11. ........... A typical layout for working clean to dirty
Figure 12. .. One method to protect a house vacuum system
Figure 13. ...........................A bag-in-bag-out filter enclosure 1
SECTION I
Introduction
This document presents information on the design, selection,
function and use of Biological Safety Cabinets (BSC), which are
the primary means of containment developed for working safely
with infectious microorganisms. Brief descriptions of the facility
and engineering concepts for the conduct of microbiological
research are also provided. BSCs are only one part of an
overall biosafety program which requires consistent use of good
microbiological practices, use of primary containment equipment
and proper containment facility design. Detailed descriptions of
acceptable work practices, procedures and facilities, described
as Biosafety Levels 1 through 4, are presented in the CDC/
NIH publication Biosafety in Microbiological and Biomedical
Laboratories (BMBL).
1
BSCs are designed to provide personnel, environmental and
product protection when appropriate practices and procedures
are followed. Three kinds of biological safety cabinets,
designated as Class I, II and III, have been developed to meet
varying research and clinical needs.
Most BSCs use high efficiency particulate air (HEPA) filters in
the exhaust and supply systems. The exception is a Class I BSC
which does not have HEPA filtered supply air). These filters and
their use in BSCs are briefly described in Section II. Section III
presents a general description of the special features of BSCs
that provide varying degrees of personnel, environmental, and
product protection.

Laboratory hazards and risk assessment are discussed in
Section IV. Section V presents with work practices, procedures
and practical tips to maximize information regarding the
protection afforded by the most commonly used BSCs. Facility
and engineering requirements needed for the operation of each
type of BSC are presented in Section VI. Section VII reviews
requirements for routine annual certification of cabinet operation
and integrity.
Introduction 2
Introduction
These sections are not meant to be definitive or all
encompassing. Rather, an overview is provided to clarify the
expectations, functions and performance of these critical primary
barriers. This document has been written for the biosafety
officer, laboratorian, engineer or manager who desires a better
understanding of each type of cabinet, factors considered for
the selection of a BSC to meet specific operational needs and
the services required to maintain the operational integrity of the
cabinet.
Proper maintenance of cabinets used for work at all biosafety
levels cannot be over emphasized. BSOs should understand
that an active cabinet is a primary safety device. A BSC must be
routinely inspected and tested by trained personnel, following
strict protocols, to verify that it is working properly. This process
is referred to as certification of the cabinet and should be
performed annually.
NOTE: A biological safety canbinet has b