Use and Maintenance of Biological Safety Cabinets 2/2

（3） Handling after use
1. Secure the used biological waste bag tightly.
2. Clean and disinfect the inner wall, rear wall, workbench, and inner side of the front window of the safety cabinet.
3. As the remaining culture medium may promote microbial growth and reproduction, all items, including instruments and equipment, should be cleaned of surface contamination and removed from the safety cabinet at the end of the experiment.
Before removing the arm from the safety cabinet, it is necessary to perform surface disinfection treatment, and then slowly remove it vertically from the work area opening.
6. After each use, the contamination on the surface of the biosafety cabinet should be removed. The workbench and inner walls should be wiped with disinfectant, and the disinfectant used should be able to kill any microorganisms in the safety cabinet. At the end of each experiment, the workbench, surroundings, and inside and outside of the glass of the biosafety cabinet should be wiped to remove surface contamination. When effective on target organisms, bleach solution or 70% alcohol can be used for disinfection. After using corrosive disinfectants such as bleach, it is necessary to wipe again with sterile water.
7. Close the front operation window and turn on the UV light.
（4） Handling of spills inside biosafety cabinets
When dealing with spills, do not insert your head into the safety cabinet, and do not face the front operating port directly. Instead, place it behind the front panel. When choosing disinfectants, it is necessary to consider their corrosiveness to biosafety cabinets.
If the spilled amount is less than 1 ml, it can be directly wiped with a tissue (or other material) soaked in disinfectant.

If there is a large amount of spillage or the container is damaged, it is recommended to follow the following steps: keep the biosafety cabinet open; Cover the spilled material with absorbent material soaked in disinfectant for a certain period of time to exert disinfection and sterilization effects. If necessary, soak the working surface, drainage ditch, and liquid receiving tank in disinfectant; After disinfecting and sterilizing the gloves worn in the safety cabinet, remove the gloves; If the protective clothing has been contaminated, remove the contaminated protective clothing and clean the exposed area with an appropriate disinfectant; Wear appropriate personal protective equipment such as double layered gloves, protective clothing, goggles, and respiratory protection devices; Be careful to collect the spilled tissue (or other absorbent material) together with the spilled material into a dedicated collection bag or container, and repeatedly use new tissue (or other absorbent material) to absorb the remaining material; Broken glass or other sharp objects should be handled with tweezers or pliers; Wipe or spray the inner wall, working surface, and inside of the front window of the safety cabinet with disinfectant; After a certain period of time, wipe the disinfectant and sterilizer clean with clean water; If it is necessary to soak the liquid receiving tank, report to the supervisor before cleaning the tank; It may be necessary to disinfect and sterilize using other methods before cleaning. If the spilled material enters the interior of the biosafety cabinet, appropriate measures need to be taken after evaluation.

（5） Regular maintenance
1. Replace the pre filter every three months.
2. Replace the UV lamp once a year.
When any of the following situations occur, on-site testing of the biosafety cabinet should be conducted: after the completion of the biosafety laboratory and before it is put into use, the biosafety cabinet has been installed; After the biosafety cabinet is moved to a new location; After conducting maintenance on the biosafety cabinet; After replacing the high-efficiency filter in the biosafety cabinet; Annual routine testing of biosafety cabinets. On site testing should be conducted by qualified professionals according to the manufacturer's instructions to evaluate the operational performance and integrity of each biosafety cabinet, in order to check whether it meets national standard requirements. The evaluation of the protective effect of the safety cabinet should include testing the integrity of the cabinet, leakage of HEPA filters, vertical airflow velocity, flow direction and average wind speed of the working window airflow, negative pressure/ventilation rate, smoke mode of the airflow, and alarm and interlock systems. You can also choose to conduct tests on leakage, light intensity, UV intensity, noise level, and vibration. During these tests, the testing personnel must undergo specialized training and use specialized techniques and equipment. It is strongly recommended to have qualified professionals conduct the testing.
Aseptic testing is conducted weekly using a method with similar airborne bacterial counts.
Before moving or replacing filters, the biosafety cabinet must be cleaned of contamination. The most commonly used method is formaldehyde fumigation, which should be carried out by qualified professionals to remove pollution.