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Fundamentals of MLS > Biological Safety Cabinets > Flashcards

Biological Safety Cabinets Flashcards

1
Q

What characteristics of organisms are the biological risk groups determined by?

A

Risk groups are determined by characteristics of organisms:
Pathogenicity
Infectious dose
Mode of transmission
Host range
Availability of effective preventative measures
Availability of effective treatment

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2
Q

What determines if a aerosol of an organism can cause disease?

A

Viability of microbe

  1. Concentration of the particles
  2. Size of the particles
  3. Bacteria and spores = 0.3 – 20 μm
  4. Viruses = 0.003 -0.05 μm
  5. Persistence of aerosol
  6. Susceptibility of the individual
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3
Q

How can aerosols be reduced?

A
  1. Using sealed centrifuge buckets
  2. Using a biological safety cabinet
    a) When manipulating samples
    b) When vortexing
    c) When aliquoting
  3. Use HEPA filters where needed
    a) On ultracentrifuges
    b) In BSC’s
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4
Q

Why are N-95 masks being used by more labs?

A
  1. Recent studies show aerosol droplets rapidly become smaller particles that may remain suspended for a longer period
  2. Large droplets may settle on surfaces and become resuspended as smaller particles
  3. More labs are utilizing N95 particle respirators if there is a potential for exposure to infectious aerosols
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5
Q

What is the construction of a typical HEPA filter and what size of particle does a standard HEPA filter remove?

A

The most critical part of a BSC is the HEPA filter – a densely pleated filter of glass and paper fibers on aluminum or wood support used to filter biological agents from the air

Standard HEPA filters remove particles of 0.3µm

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6
Q

What certifications are required for a BSC?

A
  1. BSC must comply with Canadian Biosafety Standard and be certified in accordance with National standards or manufacture specifications
  2. BSC must be certified and tested:
    a) upon initial installation
    b) When moved or repaired
    c) Annually

Proper placement of BSC in the lab is a important step in the hazard assessment process

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7
Q

What are example of processes that create aerosols from specimens or cultures that require to work in a BSC?

A
  1. Grinding tissue
  2. Preparing direct smears
  3. Plating of specimens
  4. Identification procedures for molds
  5. Vortexing
  6. Decanting/aliquoting liquids
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8
Q

When does one need to work in a BSC when protecting samples from external contamination?

A
  1. Performing procedures with sterile body fluids
  2. Cell culture procedures
  3. Preparation of media or reagent solutions aseptically
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9
Q

What are the preparation steps for the BSC?

A

Preparation:

  1. Check sash is at the appropriate height
  2. Adjust stool so sitting is a neutral position
  3. Turn off UV light (if in use) and turn fluorescent on
  4. Ensure vents are clean and unblocked
  5. Turn on blower
  6. Allow to purge for at least 5-10 minutes
  7. Check pressure gauge to verify readings are within acceptable ranges
  8. Test air flow alarm
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10
Q

What are some general precautions when working at a BSC?

A

General:
Do not disrupt airflow in BSC
Plan your work
BSC is not a storage area

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11
Q

Why is UV light not used?

A

UV light is not recommended due to limited effectiveness at disinfecting the interior surfaces of BSC

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12
Q

What are the disinfection steps for working at a BSC?

A

Disinfect
Wash hands
Don PPE appropriate for procedure and biohazard level
Disinfect interior surface

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13
Q

What is important to rules to abide by when assembling materials at a BSC?

A

Assemble required materials:
Don’t overcrowd
Do not place anything on or near vents
Cover surface with absorbent towels if needed
Organize so you work from clean, to work area, to dirty

Note: Important to place aerosol generating equipment ( vortex) towards the back of the BSC without blocking the rear grille

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14
Q

How should one perform their procedures at a BSC?

A

Perform procedure

  1. Move with slow deliberate movements
  2. Work min 4 inches from sash as far back to the rear of the work area as reasonable, arms do not rest on grille
  3. Do not remove hands until procedure is complete, should have waste available in BSC so not going in and out
  4. Work one person at a time, and from clean area to dirty area
  5. Contaminated garbage should be discarded in waste container in the BSC not outside.
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15
Q

What are some practices and things to be aware of to avoid uncontrolled air movement at a BSC?

A
  1. Avoid excess movement of hands and arms through the front opening
    This disrupts the air curtain at the front of the BSC which can allow contaminants to enter or escape the BSC
  2. Arms should enter and exit the BSC slowly and perpendicular to front opening.
  3. Keep a bottle of disinfectant in BSC while working to avoid moving in and out (spill)
  4. Open flames, flammable chemicals can disrupt airflow and damage HEPA filter
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16
Q

Describe the completion steps before leaving the work area at the BSC?

A

Completion

  1. Purge before removing hands or unloading material form BSC. Up to several minutes (manufacture recommendation)
  2. Cleanup – a) disinfect work area including sides, back, lights, and interior of the sash
    b) remove PPE
    c) wash hands
  3. Shutdown – turn off blower, remove equipment disinfect if needed
17
Q

What are the different classes and types of BSC? (just list them)

A 
Classes:
Class I
Class II
   Type A1
   Type A2
   Type B1
   Type B2
Class III
18
Q

Describe the intended use and function of a Class 1 BSC.

A

Class I
Ventilated cabinet that protects only the lab worker and environment
No product protection
Air drawn into the cabinet, exhaust air is filtered to remove infectious particles before release to the outside or back into the lab
Should not be used for toxic or flammable toxic chemicals

19
Q

Describe the personal, product and environmental protection provided by a BSC Class II.

A

Class II
1. Personal protection:
Provided by an inflow of air at the work opening which is removed through exhaust grill at the edge of cabinet
2. Product protection:
Provided by supplying re-circulated air through HEPA filters downward toward the work surface. Also called laminar flow work surface
3. Environmental protection:
Provided by HEPA filtered exhausted air

20
Q

How is the airflow different in a Class II, Type A1 BSC?

A

Class II, Type A1
(Formally known as Class II, Type A)

Cabinets may exhaust filtered air directly into the lab or thru duct system
70 % air is re-circulated in the cabinet the other 30% is HEPA filtered air put back into the lab/outside
Not to be used with flammable or toxic chemicals
0.38m/s (75 ft/min) face velocity

21
Q

What is different in the airflow with a Class II Type A2? What compounds can it be used with?

A

Class II, Type A2
(Formally known as Class II, Type B3)
Modified Class II, Type A1
Greater inflow velocity

0.5 m/s (100 ft/min) face velocity

22
Q

What compounds can a Class II Type A2 be used with?

A

May be used with trace amounts of flammable or toxic chemicals.

23
Q

Describe the intended use and airflow for a Class II, Type B1 BSC.

A

Class II, Type B1

Protects worker and product
30% of air is re-circulated in the cabinet, 70% exhausted to outside (not in lab)
May be used with small amounts of toxic and volatile chemicals and radionuclides
0.5 m/s (100 ft/min) face velocity

24
Q

Describe the filtration used and intended use for a Class, Type B2 BSC.

A

Class II, Type B2

100% HEPA filtered to outside (no exhaust in lab)
May be used with small amounts of toxic and volatile chemicals and radionuclide.

25
Q

What are the requirements when working in a Class III BSC?

A

Class III

  1. Maximum protection to worker and product
  2. Totally enclosed, air-tight
  3. Work performed through rubber gloves
  4. Ventilated cabinet by drawing room air through HEPA filers
  5. Double HEPA-filtered exhaust air to outside
  6. Used when working with highly pathogenic organisms
  7. Kept under negative pressure
26
Q

What are the daily quality control measures to be taken for working at a BSC?

A

Quality Control, Daily:

  1. Routine disinfection
    a) While blower is running wipe down all surfaces with disinfectant
    b) NOT bleach – corrosive (use 70% isopropyl alcohol)
  2. Check blower
    a) Listen to hear if it is functioning
    b) Put paper on sash to make sure it is being pulled in
  3. Record airflow gauge reading and ensure reading is within range indicated for that cabinet.
27
Q

What are the purposes of airflow gauges and what do you check?

A
  1. Measures suction and pressure within the cabinet
  2. LOW range: May indicate a clogging of filter
    MID range: OK
    HIGH range: May indicate a HEPA leak
28
Q

What are the weekly, monthly and yearly quality control practices for BSC?

A

Quality Control:

  1. Weekly: Clean UV lights by wiping with 70% ethanol if used
  2. Monthly: Clean the gutter area underneath the bench surface
  3. Yearly:
    a) Re-certify cabinet
    b) Check airflow velocity
    c) HEPA filter checked and replaced
29
Q

When does BSC re-certification need to be done?

A

When does re-certification need to be done?

  1. After installation
  2. When a BSC is moved
  3. Every year
  4. HEPA filter change
30
Q

What does BSC certification involve?

A

BSC certification involves:

  1. Measuring airflow velocities
  2. Check of HEPA filter for leaks
  3. Check airflow patterns
  4. Inflow rates and exhaust, airflow rates are balanced
  5. Physical parameters

Fundamentals of MLS (18 decks)

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