BIOSAFETY LEVELS
Biosafety levels or biohazard levels are classifications of safety precautions that are used in the
clinical microbiology laboratory to protect the workers, environment and the public. These levels
are developed by the Centers for Disease Control and Prevention (CDC) for the scientists and
other lab personnel to identity and reduce the risk while handling the harmful biological agents 1..
The four biosafety levels (BSLs) are BSL-1, BSL-2, BSL-3, BSL-4, with BSL-4 being the highest
level of containment. The intricacy of each level lines up with infectivity, transmission ability of
microorganism and disease severity and the nature of the laboratory work to be performed2..
Biosafety level 1 laboratories are used to study about microorganism or toxins that cause
minimal health hazards to the community and laboratory 1.. They follow Standard Microbiological
Practices and require no special equipment. Standard designing controls in BSL-1 laboratories
include easily cleaned surfaces that can withstand the chemicals utilized in the laboratory. An
example of microbe used in the BSL-1 is a nonpathological strain of E. coli. Biosafety level 2
laboratories work with pathogens or infectious agents that cause moderate health hazards to
the workers. Appropriate personal protective equipment like lab coats, gloves, eye protections,
face shield should be worn as needed. The lab has automatic, lockable doors and washing
sinks and eye washing stations. All procedures that cause infections are performed within a
biological safety cabinet (BSC). These labs must have decontamination equipment like
incinerator, autoclave for proper waste disposal. Example of microorganism worked within in
BSL-2 include Streptococcus pneumonia and Salmonella choleraesuis.
Biosafety level 3 laboratories work with infections agents that cause serious hazards and can
cause potentially lethal infection to the workers via respiratory exposure. Standard protective
equipment must be worn. Scrub suits and coveralls are often required. All the safety measures
BSL-2 are also followed here. These labs must use controlled and directional air flow, that flow
from the non-laboratory areas (clean areas) into the laboratory areas (potentially contaminated
areas). Another safety feature includes the use of two self-closing, interlocked doors, filtered
ventilation system, sealed windows and wall surfaces4..
Biosafety level 4 laboratories include high transmission pathogens that are more dangerous to
the community and laboratory workface. Marburg and Ebola viruses fall into this category.
These labs contain custom-designed airtight doors, dedicated supply and exhaust airflow
systems, a negative-pressure environment, and mandatory use of positive-pressure suits. All
work with the infectious agents is done in a class III BSC. The risk for the workers dealing with
dangerous pathogens is minimized through training and by following standard operating
procedures and safety protocols. The biosafety rules and procedures for working with
pathogens that require BSL-2, BSL-3, or BSL-4 containment are outlined in Biosafety in
Microbiological and Biomedical Laboratories5.. BSL-4 labs are extremely isolated and located in
a separate dedicated zone of a building. A chemical shower disinfects the surface of the
contaminated suit to prevent the contamination of the rest of the building and the person
changing the outfit6..
World health organization and CDC has outlined the biosafety guidelines for the isolation and
characterization of SARS-CoV-2. According to the guidelines a BSL-3 laboratory must be used
to isolate or culture the virus. This is to ensure the safety of professionals, workers and the
community. BSL-3 is used to work with agents that cause fatal disease through inhalation
Biosafety levels or biohazard levels are classifications of safety precautions that are used in the
clinical microbiology laboratory to protect the workers, environment and the public. These levels
are developed by the Centers for Disease Control and Prevention (CDC) for the scientists and
other lab personnel to identity and reduce the risk while handling the harmful biological agents 1..
The four biosafety levels (BSLs) are BSL-1, BSL-2, BSL-3, BSL-4, with BSL-4 being the highest
level of containment. The intricacy of each level lines up with infectivity, transmission ability of
microorganism and disease severity and the nature of the laboratory work to be performed2..
Biosafety level 1 laboratories are used to study about microorganism or toxins that cause
minimal health hazards to the community and laboratory 1.. They follow Standard Microbiological
Practices and require no special equipment. Standard designing controls in BSL-1 laboratories
include easily cleaned surfaces that can withstand the chemicals utilized in the laboratory. An
example of microbe used in the BSL-1 is a nonpathological strain of E. coli. Biosafety level 2
laboratories work with pathogens or infectious agents that cause moderate health hazards to
the workers. Appropriate personal protective equipment like lab coats, gloves, eye protections,
face shield should be worn as needed. The lab has automatic, lockable doors and washing
sinks and eye washing stations. All procedures that cause infections are performed within a
biological safety cabinet (BSC). These labs must have decontamination equipment like
incinerator, autoclave for proper waste disposal. Example of microorganism worked within in
BSL-2 include Streptococcus pneumonia and Salmonella choleraesuis.
Biosafety level 3 laboratories work with infections agents that cause serious hazards and can
cause potentially lethal infection to the workers via respiratory exposure. Standard protective
equipment must be worn. Scrub suits and coveralls are often required. All the safety measures
BSL-2 are also followed here. These labs must use controlled and directional air flow, that flow
from the non-laboratory areas (clean areas) into the laboratory areas (potentially contaminated
areas). Another safety feature includes the use of two self-closing, interlocked doors, filtered
ventilation system, sealed windows and wall surfaces4..
Biosafety level 4 laboratories include high transmission pathogens that are more dangerous to
the community and laboratory workface. Marburg and Ebola viruses fall into this category.
These labs contain custom-designed airtight doors, dedicated supply and exhaust airflow
systems, a negative-pressure environment, and mandatory use of positive-pressure suits. All
work with the infectious agents is done in a class III BSC. The risk for the workers dealing with
dangerous pathogens is minimized through training and by following standard operating
procedures and safety protocols. The biosafety rules and procedures for working with
pathogens that require BSL-2, BSL-3, or BSL-4 containment are outlined in Biosafety in
Microbiological and Biomedical Laboratories5.. BSL-4 labs are extremely isolated and located in
a separate dedicated zone of a building. A chemical shower disinfects the surface of the
contaminated suit to prevent the contamination of the rest of the building and the person
changing the outfit6..
World health organization and CDC has outlined the biosafety guidelines for the isolation and
characterization of SARS-CoV-2. According to the guidelines a BSL-3 laboratory must be used
to isolate or culture the virus. This is to ensure the safety of professionals, workers and the
community. BSL-3 is used to work with agents that cause fatal disease through inhalation
