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Biosafety level

Views: 5     Author: Site Editor     Publish Time: 2020-09-11      Origin: Site


Biosafety levels are determined for different levels of biological hazards, including requirements for laboratory personnel, laboratories, and environmental protection. According to biohazard levels, the safety of microorganisms and biomedical laboratories is divided into 4 levels to suit scientific research, Various adaptation needs such as teaching, clinical and diagnosis.

Laboratory safety

The universal biosafety level standard in the world was established by the Centers for Disease Control (CDC) and the National Institutes of Health (NIH). According to the laboratory design features, building structure, protective facilities, instruments, operations, and operating procedures required for the operation of different risk levels of microorganisms, the biological safety level of the laboratory can be divided into basic laboratory-level I biological safety level, basic laboratory -Level II biological safety level, protection laboratory-level III biological safety level and highest protection laboratory-level IV biological safety level.

Security level

The biosafety level can integrate the conditions of relevant research work safely and match the biosafety requirements of different jobs. The fundamental measure to control biosafety risks is to set the corresponding biosafety level for the work to be carried out based on the results of biosafety assessment. The biological safety level of each laboratory is determined according to the level of microbiological risk (level 1 to level 4) that can be operated safely within the physical control level. Internationally, it is based on BSL-1, BSL-2, BSL-3, and BSL-4.

Safety level of biological laboratory

Class of biological safety cabinet used





BSL-1 to BSL-3

Class I




BSL-1 to BSL-3

Class II (A1, A2, B1, B2)





Class III




1. BSL-1

Representative pathogens: measles virus, mumps virus

Introduction: The substances used in the experimental research are all kinds of microbial substances whose properties are known and have been proven not to cause disease. The research is carried out on the open experimental platform through daily procedures. No special safety protection measures are required. Operators only need to be trained in basic laboratory experiment procedures and are usually guided by scientific researchers. In such an environment, the existence of a biological safety cabinet is not required.

2. BSL-2

Representative pathogen: influenza virus

Introduction: The substances used for experimental research are some known substances that are moderately dangerous and are related to some common human diseases. Operators must be trained in relevant research operations and be guided by professional scientific researchers. Prepare for pre-treatment of substances that are prone to contamination or where contamination may occur. Some operations that may involve or produce harmful biological substances should be carried out in a biological safety cabinet. Under these conditions, it is best to use class II biological safety cabinet.

3. BSL-3

Representative pathogens: Bacillus anthracis, Yersinia pestis, Mycobacterium tuberculosis, rabies virus

Introduction: The substances used for experimental research are generally local or foreign substances that may cause people's illness or life-threatening through respiratory infection. We need to protect all operators in the surrounding environment from being exposed to these potentially dangerous substances. Usually the use of Class II or Class III biological safety cabinets is necessary.

4. BSL-4

Representative pathogens: Ebola virus, Marburg virus, Lassa virus

Introduction: The substances under test are some extremely dangerous and deadly toxic substances, which can be transmitted through the air and there is no effective vaccine or treatment method to deal with them. Operators must be proficient in conducting research on such extremely hazardous substances, and should be familiar with the prevention of these extremely hazardous substances in related operations, protection facilities, laboratory design, etc. At the same time, it must be guided by scientific researchers who are very experienced in this research field, and it is strictly forbidden to work alone in a level 4 laboratory. The entry and exit of the laboratory should be strictly controlled. The laboratory must be built separately or in a separate room in a building separated from any other place, and a detailed operation manual about the research is required for reference. In such experimental research, a Class III biological safety cabinet is necessary.

Isolation of infectious diseases

There are mainly several international standards for biological safety cabinets. The safety cabinets can be divided into three categories: Class I, Class II, and Class III to meet different biological research and epidemic prevention requirements. The classification level of the safety cabinet has nothing to do with the biological safety level.


Class I biological safety cabinet can protect the staff and the environment without protecting the samples. The air flow principle is the same as that of a laboratory fume hood, except that the exhaust port is equipped with a HEPA filter. All types of biological safety cabinets use HEPA filters at the exhaust and intake ports. The first-level biological safety cabinet does not have a fan, and relies on the fan in the external ventilation pipe to drive the airflow. Because it cannot protect the products in the cabinet, it has been seldom used.


Class II biological safety cabinet is the most widely used cabinet type. According to the regulations of NSF49, the secondary biological safety cabinet can be divided into 4 levels according to the inlet air speed, exhaust mode and circulation mode: Type A1, Type A2 (formerly Type B3), Type B1 and Type B2. All secondary biological safety cabinets can provide protection for workers, the environment and products.


The three-level biological safety cabinet is designed for the 3-4 laboratory biological safety level. The cabinet is completely air-tight. The staff can operate through the gloves connected to the cabinet. It is commonly known as the glove box. The transfer box of the door enters and exits the safety cabinet to ensure that it is not contaminated, and is suitable for high-risk biological tests.


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