1. Airflow and BSC Biosafety and Biosecurity Awareness Training
For Afghan and Pakistani Bioscientists
January 12-14, 2010
SAND No P
Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. 1 1

2. Biological Safety Cabinets (BSCs)
Primary means of containment
Three design types
Class I, Class II, and Class III
Designed to provide protection for
Personnel
Directional flow of air into cabinet
Environment
HEPA filtered exhaust
Product (except Class I)
Laminar flow of HEPA filtered air
But, how?

3. Primary Barriers – Ventilation Equipment
Personnel
Product
Environment
Chemical Fume Hoods x
Laminar Flow Clean Benches
Class I Biological Safety Cabinet
Class II Biological Safety Cabinet
Class III Biological Safety Cabinet
Isolators

4. How do HEPA Filters Work?
HEPA = High Efficiency Particulate Air
Minimum efficiency of 99.97% removal of 0.3 micron particles
HEPA filters do not filter out gases, vapors or volatile chemicals, they only filter out particulates (bacteria and viruses)

5. Class I Biosafety Cabinet
Provides personnel and environmental protection, but no product protection
Typical applications include: Housing centrifuges, fermenters, cage dumping in an animal lab
LABCONCO
A. Front opening B. Sash C. Exhaust HEPA D. Exhaust plenum
NUAIRE

6. Class II Biosafety Cabinet
Provides personnel, environmental, and product protection
Type A2
Exhaust to room or outside through thimble connection
30% recirculated, 70% exhausted
Type B2
Must be hard ducted to outside
Total exhaust (100%)
Pro: may be used with volatile chemicals
Con: more expensive to operate, harder to balance airflows in lab

7. Class II, Types A2 and B2

8. Class III Biosafety Cabinet

9. Primary Barriers: Working in Biosafety Cabinets
Proper technique is critical to maintaining personnel and product protection!
Elements
Decontamination
Setup
Work flow
Locations of supplies and waste containers
Movement in and out
Others
Workflow from clean to contaminated (“dirty”)

10. Recognizing the Limitations of BSCs
Personnel protection depends on inward airflow through the work opening
Requires proper techniques by user
Only small quantities of volatile chemicals in any type of BSC
Motors on standard BSCs are not sparkproof
Should not use bunsen burners or alcohol lamps in BSCs
Over time, heat can damage the HEPA filter
Heat can create turbulent airflow, compromising protection
And, potential for fire to destroy BSC
Buildup of flammable vapors with 70% recirculation
BSCs need to be tested and certified regularly to have assurance getting expected protection
Prior to service
After repairs or relocation
Annually

11. Secondary Barriers
Contain the agent within the room or facility in case an agent escapes from the primary barriers
Building & Room Construction
Separated from public areas
Easily cleaned
For containment laboratories:
Room penetrations sealed
Double-door entry
HVAC Issues:
Directional airflow
Exhaust filtration
Other Engineering Controls:
Solid waste treatment
Wastewater treatment
Building
Room
BSC
Tube

12. How do You Establish Directional Airflow?
Airflow Offset Control
Relies on airflow through doors at all times
“Leaky Box” concept
Provides “Zone Control” of hazards and odors
Lab
Zone 1
Lab
Zone 2
Lab
Zone 3
Directional inward airflow provided such that air will always flow towards areas of higher containment
Airflow

13. Airflow Offset Control
900 cfm Supply
1000 cfm Exhaust
How much should the offset be? – IT DEPENDS!
(USDA ARS 242.1: 15%, min 50 cfm cfm more appropriate)
Modified by P.Jennette
100 cfm
“Leaky” Level 3

14. Verifying Correct Airflow Before Entering Lab

15. Heating Ventilation and Air Conditioning (HVAC) Issues
Pressure monitoring devices at entry
Smoke test
HVAC controlled to prevent sustained positive pressurization
Interlock exhaust/supply
Alarms for HVAC failure (inside and outside the facility)
Exhaust air HEPA filtered (sometimes necessary)
Sealed ductwork
Backflow prevention on supply air (Damper, HEPA)
1978 Smallpox lab infection in Porton Down England - Exhaust failure combined with poor practices led to the escape of virus from the BL4 lab (when the lab became + pressurized without an alarm and workers were discarding waste outside of the biosafety cabinet) -- the virus was carried out of the lab through a penetration around a pipe into a research darkroom on the floor above the containment laboratory.  The infected researcher died, her mother was infected and survived, and the PI took his own life after the autopsy proved his lab was responsible for the researcher's demise.