What is Biosafety Laboratory
Laboratory is a necessary place for scientific research. According to the risk level, including the infectivity and harmfulness of infectious pathogens, biological laboratories are divided into four levels (Protection level)：P1, P2, P3 and P4) according to the Biosafety level (BSL).
The work that P1-P4 laboratories can undertake is also divided according to the safety level
Its strict level is from low to high
P1 laboratory: basic laboratory, suitable for low harm to human body, animals and plants or the environment, without pathogenic factors to healthy adults and animals and plants.
P2 laboratory: basic laboratory, suitable for pathogenic factors with medium or potential hazards to human body, animals, plants or the environment, which will not cause serious hazards to healthy adults, animals and the environment and have effective prevention and treatment measures.
P3 laboratory: protective laboratory, which is suitable for dealing with pathogenic factors that are highly harmful to human body, animals and plants or the environment, causing serious or even fatal diseases to human beings through direct contact or aerosol, or highly harmful to animals, plants and the environment, usually with preventive and therapeutic measures.
P4 Laboratory: the highest-level protective laboratory, suitable for highly hazardous pathogenic factors to human body, animals and plants or the environment, which are transmitted by aerosol or whose transmission route is unknown, or unknown and highly dangerous. There are no preventive and therapeutic measures. Like ebola.
The construction of biosafety laboratories should comply with the published "Technical Specifications for Building Biosafety Laboratories". According to the specifications, P2 laboratory should implement the first and second barriers, while P3 and P4 laboratories need to set up the first and second barriers.
The primary barrier ensures the isolation between the experimental operator and the operated object, including biological safety cabinet and positive pressure protective clothing, etc. The secondary barrier guarantees the isolation of the biosafety laboratory from the external environment, including the ventilation system. Therefore, the primary barrier and the secondary barrier are the protective umbrellas for laboratory personnel and the external environment respectively. The technical specifications for the main rooms of P3 and P4 laboratories are also detailed, including the main laboratory, buffer room of the main laboratory, isolation corridor, protective clothing replacement room, preparation room, shower area, etc. Ultra-high cleaning level, constant range of temperature, humidity and pressure difference are the guarantee of experimental safety.
Main Technical Indicators of Secondary Barrier in Biosafety Laboratory
Source: Technical Code for Building Biosafety Laboratories GB 50346-2011
You may wonder, what exactly is the top P4 laboratory like?
What exactly is P4 laboratory like
P4 Laboratory, as the highest-level biosafety laboratory, is a sharp weapon to deal with high-risk virulent viruses that cannot be prevented and treated. P4 laboratory is generally an independent building. For example, if it shares a building with other biological laboratories, it also needs to occupy an independent isolation area in the building and be completely isolated from other nearby buildings. In the common four-layer structure, the first layer is the sewage treatment and guarantee equipment, the second layer is the core experimental area, the third layer is the exhaust pipe filter layer, and the fourth layer is the air conditioning equipment and the exhaust pipe.
Basic Characteristics of P4 Laboratory
Source: National Institutes of Health, part of the United States Department of Health and Human Services
Personnel Protection in Biosafety Laboratory
1. When entering an ordinary laboratory, the experimenter only needs experimental clothing, gloves, facial protection and other equipment. However, there are potentially dangerous pathogenic factors in high-level experiments. How should researchers protect themselves?
2. As mentioned earlier, the primary barrier ensures the isolation of laboratory personnel from potential toxic bacteria. Before entering a high-grade laboratory, personnel need to go through multiple procedures, including an outer locker room, a shower room, an inner locker room, a buffer room, etc. It may take 20-30 minutes to enter the laboratory from the outside. Therefore, laboratory staff need to receive strict training before taking up their posts, and must ensure that the use process is followed after taking up their posts. In order to isolate researchers from potential pathogens, they need to wear positive pressure protective clothing with independent oxygen supply to enter the laboratory. In protective clothing, the air that the experimenter breathes comes from an independent air system, and the breathing tube needs to be replaced when moving in the laboratory, which is why many spiral tubes are hung in the laboratory.
3. For laboratories with P2 level and above, Biosafety cabinet (BSC) shall be equipped according to regulations, and pathogens with dangerous operations shall be completed in the cabinet. Biosafety cabinet is a kind of negative pressure equipment, which is also divided into different levels according to the proportion of circulating air and exhaust air. It can ensure the negative pressure in the cabinet by continuously pumping out the air in the cabinet to prevent the aerosol generated in the experimental operation from spreading outward. After the completion of the experiment, when leaving the laboratory, the personnel should take a chemical shower to disinfect and eliminate all possible viruses before finally taking off the protective device layer by layer.
The box that closes the pathogen
1. Scientists may study dangerous pathogenic factors in the laboratory, and how does the laboratory ensure that the pathogens inside the laboratory do not spread outward?
2. First of all, all biological experiments should be carried out in laboratories with corresponding safety levels according to the microbiological safety levels stipulated by the state (refer to the "List of Pathogenic Microorganisms Infected in Human Beings" http://www.nhc.gov.cn/wjw/gfxwj/201304/64601962954745c1929 e814462d0746c.shtml for details).
3. Ordinary laboratories do not have access to or experimental authority for pathogenic viruses, but they need to follow the technical specification for microbiological operations (GMT) in their operations, and instruments and consumables in contact with non-pathogenic viruses need to be sterilized by alcohol or high pressure, and the wastes are put into special garbage bags for medical wastes to ensure biological safety.
4. The secondary barriers of biosafety laboratories at all levels ensure that pathogenic factors cannot escape. Laboratory personnel need to go through layers of checkpoints before entering and leaving the laboratory from the buffer room. For P3 and P4 laboratories, the air pressure of each door in the entrance direction will gradually decrease, i.e. the directional negative pressure system, and there are multiple doors with interlocking devices installed at the same time to ensure that the two doors cannot be opened at the same time to prevent air circulation. The air inside the laboratory must be filtered by a high-efficiency filter before it can be discharged outwards. The solid wastes generated from the experiment must be thoroughly sterilized before they can be incinerated harmlessly. The sewage produced by the laboratory has also been treated perfectly by the sewage treatment system. As for the protective clothing worn by the laboratory staff, they will not be spared. Strict chemical shower disinfection can eliminate all pathogens that have been contaminated. In short, without treated gas, solid and liquid will not leave the laboratory.
5. Then you may want to ask, what if the power is cut off? What if the exhaust system fails? Don't worry! High-grade biosafety laboratories have all complied with their construction standards, and have set up backup power supply and backup exhaust fan to continuously ensure the negative pressure environment in the laboratory and maintain the safety of the laboratory. In other words, the biosafety laboratory is like a box, which uses various means to "close" the pathogen inside.
6. At present, many biosafety laboratories across the country have joined the research in novel coronavirus. Some are carrying out testing work, others are rushing to tackle scientific research and make efforts to solve the epidemic situation as soon as possible. Let's pay tribute to the scientific research workers and medical workers who are struggling in the front line!
