Home > Laboratory Construction > Laboratory Design > The four lab brothers of P1, P2, P3, P4|How to distinguish?
The rapid spread of the new coronavirus has once again brought the virus into people's sight. Not only are medical and rescue workers working hard on the front line, but scientific researchers are also intensively conducting virus research and drug experiments.
Then you might be wondering, what is the laboratory for virus experiments like? How is it different from a biological laboratory in a school or a testing laboratory in a hospital? Next, let us get to know the biosafety laboratory together.
What is a biosafety laboratory?
The laboratory is a necessary place for scientific research. According to the level of risk, including the infectivity and hazard of infectious pathogens, internationally, biological laboratories are classified into P1 (Protection level 1) according to the Biosafety level (BSL). Four levels P2, P3 and P4.
The work that P1-P4 laboratories can undertake is also divided according to the safety level, and the strict level is from low to high.
P1 laboratory: basic laboratory, suitable for low harm to human body, animals and plants or the environment, and does not have pathogenic factors for healthy adults, animals and plants.
P2 laboratory: Basic laboratory, suitable for pathogenic factors that have moderate or potential danger to humans, animals, plants or the environment. It will not cause serious harm to healthy adults, animals and the environment, and has effective prevention and treatment measures.
P3 laboratory: a protective laboratory, suitable for processing highly hazardous to humans, animals, plants or the environment, through direct contact or aerosols to infect people with serious or even fatal diseases, or highly harmful to animals, plants and the environment Pathogenic factors usually have preventive and therapeutic measures.
P4 laboratory: The highest level of protection laboratory, suitable for highly hazardous to humans, animals and plants or the environment, spread through aerosols or unknown transmission routes, or unknown, highly dangerous pathogenic factors. There are no prevention and treatment measures. Such as Ebola virus.
The construction of biosafety laboratories needs to comply with the published "Technical Specifications for Building Biosafety Laboratories". According to the specifications, P2 laboratories should implement primary barriers and secondary barriers, while P3 and P4 laboratories need to set primary barriers and secondary barriers.
The first-level barrier guarantees the isolation between the experimental operator and the operated object, including biological safety cabinets and positive pressure protective clothing, etc.; the second-level barrier guarantees the isolation between the biological safety laboratory and the external environment, including ventilation System, therefore, the first-level barrier and the second-level barrier are the protective umbrellas for experimenters and the external environment, respectively. The building technical specifications also specify the main rooms of the P3 and P4 level laboratories, including the main laboratory, the main laboratory buffer room, the isolation corridor, the protective clothing changing room, the preparation room, the shower area and other technical indicators. The ultra-high cleaning level, the constant range of temperature, humidity and pressure difference are all guarantees for experimental safety.
The main technical indicators of the secondary barrier of the biological safety laboratory
Source: Technical Specification for Biosafety Laboratory Building GB 50346-2011
You may be curious, what exactly is the highest level P4 laboratory?
As the highest-level biosafety laboratory, the P4 laboratory is a powerful tool for dealing with highly dangerous viruses that cannot be prevented and treated. The P4 laboratory is generally an independent building. If it shares a building with other levels of biological laboratories, it also needs to occupy an independent isolation area in the building and be completely isolated from other nearby buildings. In a common four-story structure, the first floor is sewage treatment and support equipment, the second floor is the core experimental area, the third floor is the exhaust duct filter layer, and the fourth floor is the air conditioning equipment and air supply and exhaust ducts.
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
When entering the ordinary laboratory, the experimenter only needs equipment such as laboratory clothes, gloves and face protection. However, there are potentially dangerous pathogenic factors in high-level experiments. How can researchers protect themselves?
As we mentioned earlier, the first-level barrier guarantees the isolation of experimenters from potential toxins. Before entering a high-level laboratory, personnel need to go through multiple procedures, including outer locker rooms, shower rooms, inner locker rooms, buffer rooms, etc. It may take 20-30 minutes to enter the laboratory from the outside.
Therefore, the laboratory staff need to receive strict training before taking up their posts, and they must ensure that they abide by the use procedures after taking up their posts. In order to isolate scientific researchers from potential pathogens, they need to wear positive pressure protective clothing with independent oxygen supply when entering the laboratory. In protective clothing, the air that the experimenters breathe comes from an independent air system, and the breathing tube needs to be replaced in the laboratory, which is why there are many spiral tubes hanging in the laboratory.
For laboratories of P2 level and above, a Biosafety cabinet (BSC) must be equipped according to regulations, and operations with dangerous pathogens must be completed in the cabinet. The biological safety cabinet is a kind of negative pressure equipment, which is divided into different levels according to the ratio of circulating air and exhaust air. It continuously extracts the air in the cabinet to ensure the negative pressure in the cabinet to prevent the air generated in the experimental operation. The sol diffuses outward. After the experiment is completed, when the personnel leave the laboratory, they must perform chemical shower disinfection to eliminate all viruses that may be contaminated, and finally take off the protective devices layer by layer.