Narrator: If you work in a laboratory environment,
you probably have seen different types of safety hoods
and cabinets that are used for different experiments
or laboratory settings.
All of these hoods and cabinets are designed
for a specific type of work.
It is important to be able to recognize each of them
and understand the work performed in them.
This video is designed to show how to properly use
a biosafety cabinet to ensure the protection of laboratory
personnel, the samples they're working with,
and the environment.
In a typical research laboratory, you
may find isolators or glove boxes,
fume hoods, laminar flow cabinets or clean benches,
and biosafety cabinets.
These are the different types of ventilation equipment used
in a laboratory to work with biological materials
or chemicals.
All of these hoods and cabinets offer different types
of protection based on airflow.
It is important to know the difference
between this equipment, to use the most appropriate
for your work.
Let's take a look and see what is different about them.
Isolators or glove boxes.
Isolators or gloveboxes are enclosed ventilation systems
that can provide a controlled environment for handling
chemicals.
They do not provide a sterile environment.
Inside the gloveboxes, there is a working space
that is completely separated from the environment around it.
Laminar flow hoods or clean benches.
The laminar flow hood is designed for sample protection,
but does not protect the user or the environment.
Room air enters the hood from the bottom front
or the top side, passes through a HEPA filter,
and then blows over the work area towards the user.
This hood offers sample protection,
and can be used when the sterility of the sample
is important, and the sample is not hazardous.
For example, for microprocessors.
Laminar flow hoods and clean benches
should not be used when working with biological materials
or chemicals.
Fume hoods.
Fume hoods are the most common type
of hood found in ASU laboratories.
The fume hood is designed to protect the user,
but does not protect the sample.
Fume hoods protect users from volatile chemicals,
toxic vapors, and flammables.
A fume hood pulls air from the lab
through the front sash of the cabinet,
and exhausts it outside of the building.
A fume hood is not suitable for work with biological materials,
because it does not protect the sample or the user
from biological hazards.
Biosafety cabinets or BSC's can be
found in laboratories where work with biological materials
is performed.
Biosafety cabinets are designed to minimize
the exposure of laboratory personnel
to aerosols or droplets when working with infectious agents
or toxins.
Biosafety cabinets are designed to protect
the user, the sample, and the environment.
An inward airflow creates an air curtain,
that along with the sash, provides protection
to the user.
The sample is protected by a HEPA filter,
downward vertical airflow in a single direction,
and at a constant speed.
The downward moving air flow splits in half
before reaching the work surface, between the front
and back grille.
This air split prevents cross-contamination
of the sample.
The air drawn to the front grille
also forms an air curtain to prevent contaminated air
from entering the work area.
Biosafety cabinets protect the environment
by filtering the exhaust air through a HEPA filter, which
removes particulate contaminants.
It is a requirement to certify the biosafety cabinet annually.
The user should check the certification date
and the magnehelic pressure before each use.
Now let's take a look at biosafety cabinets
in more detail.
Biosafety cabinets are the primary means
of containment, developed for working safely
with infectious micro organisms.
They are designed to provide protection to laboratory
personnel, the samples they are working with,
and the environment, when appropriate practices
and procedures are followed.
The HEPA filters will provide a sterile environment
by removing at least 99.97% of particulates at 0.3 microns.
HEPA filters do not remove gases and vapors.
There are three types of biosafety cabinets.
Class I, II, and III, which are designed to meet
different laboratory needs.
Let's see how each of these biosafety cabinets work.
In a class I biosafety cabinet, the air from the lab
is pulled through the front sash of the cabinet,
providing user protection.
The air is then recirculated inside the cabinet,
and eventually is exhausted through a HEPA filter
into the building exhaust system or back out into the lab,
providing protection to the environment.
Generally class I biosafety cabinets
are used for equipment or procedures
that can generate aerosols.
Biohazardous materials might be used when the sample's
sterility is not a concern.
Now let's look at a class II biosafety cabinet.
In a class II biosafety cabinet, the air from the lab
is pulled through the front sash of the cabinet,
providing user protection.
Then the air is pushed through a HEPA filter
downward over the work surface, providing sample protection.
The exhaust air is filtered by a HEPA filter,
providing protection to the environment.
Class II biosafety cabinets are the most common
in laboratories.
They are used for biohazardous materials.
For example, working with cell cultures, human blood
and tissue, viruses, and bacteria.
There are two types of class II biosafety cabinets, A and B,
depending on where the air from the cabinet
is exhausted out to.
In class II biosafety cabinets type A, 70% of the airflow
is recirculated back to the work surface.
The remaining 30% is exhausted either back to the lab,
or to the building exhaust through a canopy.
No flammable gases or volatile toxic chemicals
should be used in this cabinet.
In class II biosafety cabinets type B1, 30% of the airflow
is recirculated back to the work surface.
The remaining 70% is exhausted to the building
exhaust through a different connection.
No flammable gases or volatile toxic chemicals
should be used in this cabinet.
In class II biosafety cabinets type B2, 100% of the airflow
is exhausted to the building exhaust system
through a direct connection.
In this cabinet volatile toxic chemicals
can be used in combination with high risk biohazards.
Always remember, it is not a substitute for a fume hood.
A common feature in most biosafety cabinets
is the ultraviolet lamps or UV lamps.
For years, the UV light was considered a method
to provide a clean and sterile environment inside the cabinet
when not in use.
However, there are several limitations
for the effective use of UV light for decontamination.
For example, the lamp requires cleaning
to remove dust and dirt.
The germicidal effect of the UV light
will decrease with more time of use.
The UV light is not effective against all types
of biohazards.
The UV light will not reach any area of the cabinet workspace
that is covered.
For all of these reasons, the Centers for Disease Control
and Prevention and the National Institutes of Health
do not recommend, or require, UV light in biosafety cabinets.
Next we'll look at how to use a biosafety cabinet.
How to use a biosafety cabinet, preparing for use.
First, prepare your standard operating procedures and lab
protocols.
Then, carefully plan your experiments,
paying particular attention to all the materials and equipment
needed.
Pre-planning prevents crowding in the cabinet, and the inside
out motions that disrupt the cabinet airflow.
Put on appropriate personal protective equipment or PPE.
PPE protects you from the agents you are working with,
and prevents contamination of samples by skin flora.
PPE, at minimum, should be a lab coat, gloves,
and eye protection.
Whenever possible, tuck lab coat cuffs inside the gloves.
If the UV light is on, turn it off.
Then turn on the cabinet blower and light.
Verify underneath the biosafety cabinet
that the drain valve is closed.
Check the certification sticker and ensure
the biosafety cabinet has been certified within the last year.
Check the pressure value reading on the magnehelic gauge
and compare it with what is recorded on the certification
tag.
If the reading is equal or within 10% higher,
the cabinet is safe to use.
If the reading is lower, the HEPA filter might be damaged,
and the cabinet is unsafe to use.
If the reading is noticeably higher,
the HEPA filter may require service,
as it could be clogged with impurities
or there might be other mechanical problems.
In these cases, place a sign stating
that the biosafety cabinet is not safe to use,
and notify your supervisor or lab manager.
Allow the blower to run for 15 minutes before beginning work.
This allows the air in the cabinet
to complete a full cycle and purge any contaminants.
After the cabinet has been purged,
disinfect the interior surfaces of the cabinet
with the appropriate disinfectant.
Spray all of the internal surfaces and wait
for the appropriate contact time, then wipe.
Be careful not to allow your head
to enter the cabinet while wiping.
If using a corrosive disinfectant,
follow with a wipe of 70% ethanol to remove residue.
While the cabinet is purging, or disinfecting,
gather all the materials you will
be using for your protocol, including absorbent materials
and disinfectant for cleaning and for spill response.
Decontaminate the surface each time
before placing them in the cabinet.
Avoid overloading the cabinet as this
will compromise its efficiency.
Do not block the front or rear grille
with any material or equipment.
Set up the workspace at least six inches inside the cabinet.
Good practice is to delineate a work area
in the middle of the biosafety cabinet, in front of you.
Place items within close reach and position
to limit crossing your hands when reaching for them.
This helps to reduce airflow disruption.
Create separate areas for clean items and waste,
placing decontaminated materials toward the back of the cabinet.
Adjust your chair so that arm pits are level
with the bottom of the sash.
This will protect your face from infectious aerosols.
Next, we will begin our work in the biosafety cabinet.
Working in a biosafety cabinet.
Before beginning work, limit access
to the area around the biosafety cabinet
to minimize disruption of airflow,
airborne contaminants, unnecessary distractions,
and talking.
Conduct work in the biosafety cabinet
by following good aseptic techniques.
Avoid sneezing, coughing, or talking
while working in the biosafety cabinet,
to minimize the spread of airborne microbes.
Always make measured controlled movements
to avoid airflow disruption.
Avoid extra movements such as getting up from the cabinet
during work, or adding or removing materials in and out
of the cabinet.
When transferring liquids or pipette mixing,
always use slow and careful motions
to prevent splashes and aerosols.
Handle one sample at a time.
Keep Petri dishes, plates, flasks, bottles, tubes,
and pipette tip boxes closed or capped when not in use.
Transfer infectious materials and waste as far back
into the cabinet as possible.
Discard all contaminated materials
in a bag inside the designated waste
area of the biosafety cabinet.
Close the bag and replace it when two-thirds of the bag is full,
or at the end of your work.
Do not use a Bunsen burner or an open flame inside
of the biosafety cabinet.
Now that we've completed all of our work
inside the biosafety cabinet, let's review
how to clean the cabinet.
Removing items from the biosafety cabinet.
Once the work inside the biosafety cabinet is completed,
wait five minutes in order to purge the air
from the contaminants, before exiting the cabinet
and removing the items.
After exiting the cabinet, remove your gloves
and replace them with a new pair.
Surface decontaminate all of your items
inside the biosafety cabinet before removal.
First remove samples that need to be placed in incubators,
refrigerators, or freezers.
Then remove all other items except for waste.
Collect waste in the biohazard bag,
close the bag inside of the cabinet,
and wipe with disinfectant before removal.
Disinfect all cabinet surfaces.
Turn off the light and the blower.
Remove all PPE and dispose of the biohazard waste.
Wash your hands with soap and water.
Now, let's review what to do in case of a spill.
Spill response procedures.
If a spill occurs inside the biosafety cabinet,
ensure the drain valve on the bottom of the cabinet
is closed.
Immediately cover any spill with absorbent material,
such as paper towels.
Also place absorbent material around the spill to contain it.
Pour disinfectant directly onto the absorbent material.
Wait for the appropriate contact time,
then remove the absorbent materials.
After decontaminating the work surface,
determine if the spill has leaked into the lower tray.
To clean the tray, lift the work surface
and flood the tray with disinfectant.
Wait for the appropriate contact time before absorbing.
While the tray is disinfecting, remove the work surface
and all associated parts.
Spray them with disinfectant and wait the appropriate contact
time.
Wipe down and reinstall all parts.
After the spill is cleaned, continue
with the usual decontamination procedure
by spraying the inside of the surface with disinfectant,
waiting for the appropriate contact time, and then wiping.
If using a corrosive disinfectant,
follow with a wipe of 70% ethanol to remove residue.
Collect waste in the biohazard bag,
close the bag inside the cabinet,
and wipe with this infected before removal.
For any spill, notify others working in the lab nearby,
and report the spill to the laboratory's P.I.
and to ASU's environmental health and safety.
Maintenance and repair.
The biosafety cabinet should be positioned in an isolated
corner to minimize disruption of the air intake arising
from traffic or drafts from doors, windows, ventilation,
or equipment.
Review and follow the manufacturer's recommendations
for maintaining the biosafety cabinet.
Work surface and interior decontamination
should be conducted at the end of each workday.
Removal and complete decontamination
of the work surface, grilles, and other parts
should be conducted periodically.
Any malfunction of the biosafety cabinet must be reported.
Do not use the cabinet until you verify
the repairs have been made.
All repairs to the biosafety cabinet
must be performed by a qualified technician.
The principal investigator of the lab
is responsible for ensuring the biosafety cabinet is certified
annually.
The biosafety cabinet must be certified
by an NSF/ANSI standard 49 qualified technician.
A new certification is also required
after installation, moving, filter changes, and repairs.
If you have any questions about this biological safety cabinet
training video, please contact ASU
EHS biosafety at 480-965-1823, or email biosafety@asu.edu.
This has been a presentation by the Arizona State University
Environmental Health and Safety Biosafety and Biosecurity Team.