A biosafety laboratory is a biological/animal laboratory that can avoid or control the hazards of harmful biological factors being operated and meet biosafety requirements through protective barriers and management measures. According to the degree of biological hazard of the objects handled by the laboratory, it can be divided into different levels. The higher the level, the higher the protection level, and the higher the degree of danger of the pathogenic microorganisms being operated.

The safety level of biological laboratories is divided into: ‌ Biosafety Level 1 Laboratory, Biosafety Level 2 Laboratory (BLS-2, ABSL2, P2) Biosafety Level 3 Laboratory (BSL-3, ABSL-3, P3) Biosafety Level 4 Laboratory (BSL-4, P4) According to the function, it can be divided into PCR laboratory, blood bank laboratory, biochemical immunology laboratory, clinical testing laboratory, clinical microbiology laboratory, scientific research laboratory and fever clinic laboratory. For relevant construction specifications, please refer to “Technical Specifications for Biosafety Laboratory Buildings GB 50346-2011” and “General Requirements for Laboratory Biosafety (GB19489-2008)”.

Biosafety Level 1 Laboratory

It is suitable for operating microorganisms that do not cause human or animal diseases under normal circumstances. The operation, safety equipment and experimental facilities design and construction of biosafety level 1 laboratories are only suitable for basic teaching and research, and for handling microorganisms of hazard level 1. BSL-1 is the basic level of biosafety protection, relying on standard microbial operations to ensure safety, and lacks special level 1 or level 2 protection barriers. Under normal circumstances, biosafety level 1 laboratories can only perform non-infectious operations.

Biosafety level 2 laboratories

Applicable to the operation of microorganisms that can cause human or animal diseases, but generally do not pose a serious hazard to humans, animals or the environment, have limited transmission risks, rarely cause serious diseases after laboratory infection, and have effective treatment and prevention measures. The operation, safety equipment and experimental facilities design and construction of biosafety level 2 laboratories are suitable for clinical, diagnosis, teaching, and handling microorganisms of hazard level II.
BSL-2 laboratories have improved their functions on the basis of BSL-1 facilities, such as the laboratory door can be closed automatically and equipped with a visual window; no special ventilation equipment is required, but the windows are required to be open and installed with insect screens; reliable power supply and emergency lighting, incubators, biosafety cabinets, refrigerators are preferably equipped with backup power; laboratory exits have clearly identifiable signs in the dark, etc.

Biosafety Level 3 Laboratory

It is suitable for operating microorganisms that can cause serious diseases in humans or animals and are more easily transmitted directly or indirectly between people, animals and animals. The operation, safety equipment and experimental facilities of the biosafety level 3 laboratory are suitable for special diagnosis and research, and the treatment of microorganisms of hazard level III. The dangers of BSL-3 laboratories are mainly through skin breaks, oral ingestion and inhalation of infectious aerosols. BSL-3 laboratories protect experimental operators and the surrounding areas from contamination through primary and secondary protection barriers. Its secondary barrier includes controlled access channels and ventilation facilities filtered by high-efficiency filters.

BSL-3/P3 not only ensures the quality of the experiment, but also ensures the safety of operators and eliminates environmental pollution. Under the condition of ensuring a certain degree of cleanliness, the laboratory must present a certain negative pressure to ensure that indoor polluted gases do not leak, and indoor pollutants and gases must be treated and discharged.

In terms of plane layout, pay attention to the division of protection areas, non-protection areas, and buffer rooms. There are automatic closing and interlocking functions between each area. The transfer window must also have interlocking and physical disinfection devices, and pay attention to the separation of human and logistics flows. In terms of enclosure structure, the material selection requires smooth corrosion resistance, waterproof, easy disinfection and cleaning, sealed gaps, and the doors must be able to close automatically.

Biosafety Level 4 Laboratory

It is suitable for operating microorganisms that can cause very serious diseases in humans or animals. The operation, safety equipment and experimental facilities of the Biosafety Level 4 Laboratory are suitable for operating very dangerous exogenous biological factors or unknown highly dangerous pathogenic factors. The operating objects are usually hazard level IV or those unknown microorganisms with similar characteristics to hazard level IV microorganisms. The dangers of BSL-4 laboratories are mainly through mucous membranes or broken skin, and inhalation of infectious aerosols through the respiratory tract. Laboratory personnel are completely isolated from infectious aerosols through Class III biosafety cabinets or Class II biosafety cabinets plus positive pressure suits, and BSL-4 laboratories have complex special ventilation devices and waste disposal systems.

In addition to meeting the requirements of Biosafety Level 3 laboratories, Biosafety Level 4 laboratories must also be built in independent buildings or independent isolation areas in buildings. Equipped with access control measures to strictly restrict access to the laboratory, the personal information of the entrants, entry and exit time, authorized activity areas and other information should be recorded; there should also be strict and reliable security measures for key areas related to laboratory operations to avoid unauthorized entry. The auxiliary work area of ​​the laboratory should at least include a monitoring room and a clean clothing change room.

The laboratory protection area suitable for microorganisms with operation hazard level II should at least include a protection corridor, an inner protective clothing change room, a shower room, an outer protective clothing change room and a core workroom, and the outer protective clothing change room should be an airlock. The protection area for laboratories with operation hazard level IV should include a protection corridor, an inner protective clothing change room, a shower room, an outer protective clothing change room, a chemical shower room and a core workroom. The chemical shower room should be an airlock, with conditions for cleaning and disinfecting the surface of special protective clothing or transfer items, and conditions for using a life support gas supply system.