Working safely in you biological safety cabinet Part 3

Here is Part 3 of this blog series to guide you in working safely in your BSC. 

9. Seek annual certification of your cabinet.

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This ensures cabinet airflows and containment factors are within safe limits. The cabinet should also be re-certified if it is physically relocated to ensure no filter damage has occurred. 

Evaluation of the effectiveness of cabinet containment should include tests for cabinet integrity, HEPA filter leaks, downflow velocity profile, face velocity, negative pressure/ventilation rate, air flow smoke pattern, and alarms and interlocks.

Special training, skills and equipment are required to perform these tests and it is highly recommended that they are undertaken by a qualified professional.

10. Observe surface decontamination.

Decontaminate work zone with cleaning agents after every use. Germicidal UV-lamps are not a substitute for good cleaning practices.

Materials to be placed inside the cabinet should be surface-decontaminated with 70% alcohol.

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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 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.

11. Allow purge cycles.

Leave the blower on (at least 5 minutes) before and after use so as to purge the work zone of any contaminants.

*Purge – to allow time for contaminated air to be removed from the cabinet environment

12. Observe correct sash opening height.

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Always set the sash to the work height when working in the cabinet. If the sash window is fully open or above the normal operating height, it may compromise your safety. 

Always remember, SAFETY FIRST before anything else.

Working safely in your biological safety cabinet Part 2

Here is Part 2 of this blog series to guide you in working safely in your BSC. 

4. A Bunsen Burner should not be used.

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Burners can cause an outflow of air from inside the cabinet that can endanger the operator ~ YOU.

On Class II cabinets, protection against cross contamination may also be compromised. There have been incidents where the sash of a recirculating Class II safety cabinet was closed while the burner was still on, causing heat to build up in the cabinet that damaged the filters.

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5. Do not use the cabinet as storage area.

Overloading the cabinet with unnecessary items can affect cabinet airflow and containment. It could result to serious damage.

6. Proper cabinet location is critical.

External airflow disturbances can compromise containment.

The integrity of unidirectional 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 a location remote from traffic and potentially disturbing air currents. Whenever possible a 30cm clearance should be provided behind and on each side of the cabinet to allow easy access for maintenance. A clearance of 30-35cm above the cabinet may be required to provide for accurate air velocity measurement across the exhaust filter and for exhaust filter changes.

7. Always operate the unit continuously. 

Most BSCs are designed to permit operation 24hr/day. 

Investigators find that continuous operation helps to control the levels of dust and particulate materials in the laboratory.

Class II Type A1 and 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 II Type B1 and B2 BSCs, which have hard-duct installations, must have air flow through them at all times to help maintain room air balance.

8. Minimize disturbances to airflow barrier.

Work in a controlled and steady manner, avoiding rapid movements. Minimize arm movement; make slow movements to avoid disrupting cabinet airflow.

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Always remember, SAFETY FIRST before anything else.

Working safely in your biological safety cabinet Part 1

Well, you have decided to buy a new biosafety cabinet. Or you have an existing BSC in your lab. Are you not excited to conduct your microbiological experiments? 

But wait. Are you sure you're working safely in your biological safety cabinet?

Here is Part 1 of this blog series to guide you in working safely in your BSC. 

1. Do not confuse Laminar Flow Cabinets with Biosafety Cabinets. Yes, they look similar. But remember, laminar flow cabinets only protect samples inside the work zone from external airborne contamination. They do not protect the operator. Moreover, it is really difficult to determine  a Class II BSC from a Vertical Laminar Flow Cabinet. 

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So how will you determine a BSC is a BSC and not Laminar Flow Cabinet then? 

Here are a few tips.

a. Class II Biosafety Cabinets always have a front sash (either hinged or sliding). A laminar flow cabinet may or may not have a front cover, but a BSC always has one.

b. Front grilles. Operator and product protection is created by the air curtain from both the inflow and downflow that goes into the front air grille. Class II BSCs have front air grilles, while laminar flow cabinets don't.

c. Biohazard symbol. I know this sounds silly, but have you seen a laminar flow cabinet with a biohazard sticker on it? Well, a biohazard sticker is only attached to biosafety cabinets and not laminar flow cabinets. You know why? Because BSCs provide operator protection against biohazards.

Do not rely entirely on the physical differences since different models and brands for BSCs and Laminar Flow Cabinets have different design and features. 

2. Do not use the cabinet for agents of extreme hazard. The suitability of BSCs for your application should be ascertained by an industrial hygienist or your safety officer. Do not use the BSC with any toxic flammable or explosive materials. Take note that volatile or toxic chemicals should not be used in BSCs that recirculate exhaust air to the room. 

3. Do not operate the cabinet if any of the alarms are activated. BSCs can be equipped with one of two kinds of alarms.

a. 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.

b. 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 notified.

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Always remember, SAFETY FIRST before anything else.