The use of exhaust ventilation and filtration design in the laboratory cannot be separated from the three-level filtration of initial efficiency filter, medium efficiency filter, and high-efficiency filter. The air filtered by the internal high-efficiency filter discharged from the biosafety cabinet can be directly discharged into the atmosphere through the exhaust duct of the system, or sent to the exhaust system of the building. Ensure pressure balance between the biosafety cabinet and the exhaust system.

e) The inlet air of the laboratory should be filtered through three stages: primary efficiency filter, medium efficiency filter, and high-efficiency filter.

f) The exhaust of the laboratory must be treated with high-efficiency filters or other methods and discharged directly into the air at a speed of no less than 12m/s. The exhaust outlet should be located far away from the system inlet. The processed exhaust can also be discharged into the building's exhaust duct, but it cannot be sent back to any part of the building.

g) The high-efficiency filters for air intake and exhaust must be installed in the air vents located on the enclosure structure of the laboratory to avoid contaminating the air ducts.

h) In the ventilation system of the laboratory, airtight regulating valves should be installed at the inlet and outlet main pipes, and can be completely closed if necessary for indoor chemical fumigation and disinfection.

i) All components used in the ventilation system of the laboratory must be airtight. The high-efficiency filter used shall not be a wooden frame.

j) An automatic interlock device for fan startup should be installed to ensure that the exhaust fan is turned on first before the supply fan when starting the laboratory. Turn off the supply fan first and then the exhaust fan when shutting down.

k) Split air conditioners are not allowed to be installed in the laboratory.

Safety devices and special equipment

a) Level II or III biosafety cabinets must be installed in the main laboratory. Its installation position should meet the requirements of 6.3.2.5d).

b) Continuous flow centrifuge or other equipment that may produce aerosols should be placed in a physical suppression device, which should be able to filter the aerosols it may produce through a high-efficiency filter and discharge them. All other exhaust devices (fume hoods, exhaust hoods, etc.) that must be installed in the laboratory must be filtered through high-efficiency filters before being discharged. The indoor layout should be conducive to forming an airflow pattern that flows from the "clean" area to the "polluted" area.

c) A high-pressure sterilization pot or other disinfection device that does not generate steam must be installed in the laboratory.

d) Transfer windows should be set up between the experimental room and the outside. Both doors of the transfer window should not be opened simultaneously, and a physical disinfection device should be installed inside the transfer window. Infectious materials must be placed in sealed containers and can be transmitted through transfer windows.

e) A pressure display alarm device must be installed prominently at the entrance of the laboratory to display the negative pressure status in the experimental and buffer rooms. When the negative pressure indicator deviates from the preset range, it must be able to issue an alarm to personnel inside and outside the laboratory through sound, light, and other means. The display of the airflow resistance of the high-efficiency air supply and exhaust filters can be added to the device.