The application of knowledge, techniques and equipment to prevent a personal laboratory and environmental exposure to potentially infectious agents or biohazard is known as biosafety.
Biosafety defines the containment conditions under which infectious agents can be safely manipulated.
The objective of containment is to confine biohazard and to reduce the potential exposure of the laboratory worker, persons outside of the laboratory, and the environment to potentially infectious agents.
The application of knowledge, techniques and
equipment to prevent a personal laboratory and
environmental exposure to potentially infectious
agents or biohazard is known as biosafety.
Biosafety defines the containment conditions
under which infectious agents can be safely
The objective of containment is to confine
biohazard and to reduce the potential exposure of
the laboratory worker, persons outside of the
laboratory, and the environment to potentially
The backbone of the practice of biosafety is risk
assessment. While there are many tools available
to assist in the assessment of risk for a given
procedure or experiment, the most important
component is professional judgment.
Risk assessment should be performed by the
individual most familiar with the specific
characteristics of the organisms.
Biological safety cabinet:
This equipment is designed for controlling
aerosols and micro particles associated with
managing potentially toxic or infectious biological
material in laboratories.
Safety cabinets have been designed to protect
the user, the environment and the sample
manipulated using appropriate ventilation
They are also known as laminar air flow
cabinets or biosafety cabinets.
Classification of infective micro
organisms by risk group:
The following guidelines are recommended by the
centers for disease control and prevention and
the National Institutes of Health. Four biosafety
levels ( BSLs) are described :
Risk group 1: No or low individual and
Risk group 2: Moderate individual risk, low
Risk group 3: High individual risk, low
Risk group 4: High individual and community
1.Biosafety level 1:
Biosafety level 1 (BSL-1) is suitable for work
involving agents of no known or minimal potential
hazard to laboratory personnel and the
The laboratory may be integral to general traffic
patterns in the building.
Work may be conducted on open bench tops.
Special containment equipment is neither
required nor generally used.
Laboratory personnel shall have specific training
in procedures conducted in the laboratory.
Standard practices for BSL-1
The laboratory shall have an established policy
for the safe handling of sharps.
Eating, drinking and applying cosmetics are not
Laboratory personnel shall wash their hands after
they handle viable materials and animals and
before leaving the laboratory.
Work surfaces shall be decontaminated once a
day and after any spill of viable materials.
Safety equipment for BSL-1
It is recommended that laboratory coats, or
uniforms be worn for prevention.
Gloves should be worn if skin is broken or
afflicted by a rash.
Laboratory facilities for BSL-1
The laboratory shall be designed so that it can be
Bench top shall be impervious to water and
resistant to acids, alkali and organic solvents and
Each laboratory shall contain a sink for hand
2.Biosafety level 2:
Biosafety level 2 is similar to level 1 and is suitable
for work involving the agents of moderate
potential hazards to personnel and the
environment. It differs in that ;
Laboratory personnel are specifically trained to
handle pathogenic agents.
Access to the laboratory is limited when work is
Extreme precautions are taken with contaminated
Special practices for BSL-2
Laboratory personnel receive appropriate
Receive appropriate training on the potential hazards
A high degree of precaution must always be taken
with any contaminated Sharp items.
Broken glassware must not be handled directly.
Containers of contaminated needles, sharp
equipment, and the broken glass are decontaminated
Cultures, tissues and specimens of body fluids are
placed in a container that prevents leakage during
collection, handling, processing, storage, transport.
Work surfaces should be decontaminated with an
Safety equipment for BSL-2
Properly maintained biological safety cabinets or
other appropriate personal protective equipment
or physical containment devices are used
Face protection (goggle, mask, or other splatter
guards) is used.
Personal protective coat, gowns are worn in the
Laboratory facilities for BSL2
The laboratory is designed so that it can be easily
An eyewash facility is readily available.
Biological safety cabinets shall be installed in
such a manner that fluctuations of the room
supply and exhaust air do not cause them to
operate outside their parameters for containment.
3.Biosafety level 3:
The containment laboratory - Biosafety level 3 is
designed and provided for work with Risk group 3
micro organisms and with large volumes or high
concentration of Risk Group 2 micro organisms
that pose an increased risk of aerosol spread.
Biosafety Level 3 containment requires the
strengthening of the operational and safety
programmes over and above those for basic
laboratories -Biosafety Levels 1 and 2.
Special practices for BSL 3
The international biohazard warning symbol and sign
displayed on laboratory access doors must identify
the Biosafety level and indicates any special
conditions for entry into the area ex: immunization
Front-buttoned standard laboratory coats and half
sleeves that do not fully cover the forearms are
Open manipulation of all potentially infectious
materials must be conducted within a biological safety
Respiratory protective equipment are necessary
laboratory procedures or working with animals
infected with certain pathogens.
Laboratory design for BSL 3
The laboratory must be separated from the areas
that are open to unrestricted traffic flow within the
Surfaces of walls, floors and ceiling should be
water resistant and easy to clean.
The laboratory room must be sealable for
There must be a controlled ventilation system that
maintains a directional airflow into the laboratory
Laboratory facilities for BSL3
The objective of Health and medical surveillance
programme for basic laboratories - Biosafety
Levels 1 and 2 also apply to containment
laboratories - Biosafety level 3, except where
modified as follow :
Medical examination of all laboratory personnel
who work in containment laboratories.
After a satisfactory clinical assessment, the
examiner may be provided with a medical contact
card stating that he / she is employed in a facility
with a containment laboratory - Biosafety Level 3.
4.Biosafety level 4:
The maximum containment laboratory - Biosafety
level 4 is designed to work with Risk Group 4
Before constructing such laboratories and putting
them into operation, intensive consultation should
be done with institutions are experienced in
operating similar laboratories.
Operation of maximum containment laboratories
‘Biosafety Level 4’ should be under the control of
national or other authorized health authorities.
Special practices for BSL 4
Along with BSL 3 practices following codes must
The two person rule should be applied, whereby
no individual ever works alone.
A complete change of clothing and shoes is
required prior to entering and upon exiting the
Personnel must be trained in emergency
extraction procedures in the event of injury or
Laboratory design and facilities for BSL 4
Passage through a minimum of two doors prior to
entering the rooms containing the class III biological
safety cabinets is required.
A protective suit laboratory with self- contained
breathing apparatus differs significantly in design and
facility requirements from a Biosafety level 4
laboratory with class III biological safety cabinets.
The maximum containment laboratory - Biosafety
Level 4 must be located in a separate building or in a
clearly delineated zone within a secure building.
All effluents from the suit area, decontamination
chamber, shower or class III biological safety cabinet
must be decontaminated before final discharge.
Heat treatment is the preferred method.