The document outlines the four biosafety levels (BSL) that establish the necessary precautions in laboratory settings to protect personnel, the environment, and the public from infectious agents. BSL 1 covers basic safety with low-risk agents, BSL 2 involves moderate-risk pathogens requiring additional precautions, BSL 3 addresses high-risk agents that can cause severe disease, and BSL 4 is for handling the most dangerous pathogens with strict safety measures. Each level specifies appropriate practices, equipment, and examples of pathogens associated with various risk levels.

1. Biosafety Levels

2. Biosafety:-
• Biosafety means safety from the exposure to infectious agents.
Biosafety levels:-
Biosafety levels (BSL) are used to identify the protective measures
needed in a laboratory setting to protect workers, the environment,
and the public.

3. Biosafety Levels
4 Biosafety Levels​-
•Biosafety level 1
•Biosafety level 2
•Biosafety level 3
•Biosafety level 4

4. 1.Biosafety Level (BSL 1) :-
Basic teaching, Research
.Works with least dangerous agents, require fewest precautions.
.Agents not known to cause disease in healthy adults.
.Work can be performed on an open table or open bench.
.Basic precaution is taken such as wearing gloves, protecting eyewear, sink for washing hands etc.
.No eating, No drinking, applying cosmetics and mouth pipetting.
.Openable windows must have screen.
.The lab is not necessarily separated from the building.
. Regular disinfection/decontamination must be done atleast once per day.
.Maintenance of insects/rodents control program.
.Decontamination of laboratory wastes.
.Some organisms may cause disease in immunocompromised individuals.
.Agents include Bacillus subtilis, Salmonella spp., non pathogenic E.coli species.
Types Of Biosafety Levels:-
There are 4 types of biosafety levels according to the risk factors involved depending on the
nature of pathogen being handled:

5. 2. Biosafety level 2(BSL 2):-
Primary health services, diagnostic services and research
.BSL 2 is same like BSL 1, but few modifications are made since this level includes risk factors more than BSL 1.
.It includes various bacteria and viruses that cause only mild disease to human.
.It is suitable for work involving agents of moderate potential hazard to personnel & environment.
.Agents do not cause lethal infections & not communicable through airborne route.
. Extreme care should be taken with contaminated needles and sharp lab instruments.
.Restricted access, control of waste disposal, protective clothing and no food & drinking.
.Effective treatment and preventive measures are available.
.Biosafety cabinets should be decontaminated regularly.
.First aid , medications on accidental cases is must.
.Exposure to mucous membranes must be avoided.
.Common examples of pathogen are : Hepatitis A,B,C ,Heroes simplex virus ,Measel virus etc

6. Biosafety level 3 (BSL 3) :-
Special diagnostic services , Research
.This level is applicable for clinical, research, teaching , diagnostic & production facilities in which
work is done with indigenous or exotic agents which may cause severe and potentially lethal disease
after inhalation.
.It includes various bacteria, parasites and viruses that can cause severe & fatal diseases in humans
but for which treatments exist.
.Strict access control to lab.
.Protective clothing, gloves ,lab coat , PPE kit are very
necessary to wear.
.Face shield mask ,goggles, closed shoes and automatic or elbow taps on sink.
.Windows should be closed and sealed.
.Proper decontamination of waste before disposing.
.Common example of pathogen: Mycobacterium tuberculosis, Yersinia pestis.

7. 4. Biosafety level 4 (BSL 4):-
• Dangerous pathogen units
.This level is required for work with dangerous and exotic agents that have a high individual risk of
aerosol – transmitted laboratory infections , agents which cause severe & fatal disease in humans for
which vaccines or other treatments are not available.
.Lab is separate.
. Special waste disposal.
.Vacuum room, ultra violet room.
.Multiple showers at entry & exit.
.Strictly controlled access to the laboratory .
.Changing clothing before entering and exiting lab.
. Dangerous and exotic agents with high risk of life – threatening disease, aerosol transmitted.
.Supervised by qualified scientists who are trained and experienced in working with these agents.
.Examples of pathogens are :- Ebola virus, Marburg virus, Lassa fever.

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