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How to sterilise a biosafety cabinet

Biological Safety Cabinets are equipment that protects samples, operators and the environment in a tripartite manner and therefore need to be effectively disinfected at regular intervals or when: before replacing exhaust/sink air filters or fans; before entering a contaminated positive or negative pressure chamber of the cabinet; in the event of an accidental leak that contaminates an inaccessible surface; before performance verification or recertification, especially to achieve Biosafety Level 3 or 4; or before the cabinet is relocated.
Disinfection must be carried out by qualified professionals, using personal protective equipment such as gloves, disposable suits and masks that filter gases and vapours. In the past, formalin gas was often used as a disinfection solvent, obtained by evaporating a 37% solution of formalin or by depolymerising solid polymethanes. However, disinfection with formalin has the following disadvantages: the need to evacuate staff and shut down the laboratory when disinfection is carried out; the time-consuming nature of the operation; the need for engineers to intermittently turn on fans to circulate formalin vapour and the need to cover exhaust filters with plastic bags.
Due to the large amount of residue generated by disinfection, it needs to be thoroughly cleaned again after disinfection or before use. Due to the adverse health effects of formalin gas, the use of formalin has been banned in many countries and chlorine dioxide gas and hydrogen peroxide vapour are gradually being used instead of formalin for disinfection.
Chlorine dioxide disinfection is carried out by injecting chlorine gas into a tank filled with solid sodium chlorite, producing a yellow-green chlorine dioxide gas. Chlorine dioxide disinfection is somewhat faster than formalin and leaves less residue after disinfection. As a gas, chlorine dioxide diffuses quickly and does not require the fan of the biosafety cabinet to be switched on. It only takes one hour of contact time to kill organisms quickly and efficiently; the process of chlorine dioxide disinfection is as follows: cover with plastic hood, seal the safety cabinet, chlorine dioxide outgassing, chlorine dioxide contact and washing, tear off the plastic hood and clean the residue. It takes about 3.5 hours in total and is simple and efficient.
Hydrogen peroxide disinfection is achieved by rapid evaporation of the water-soluble hydrogen peroxide mixture, producing a vapour that is diffused throughout the cabinet. There are two main types of hydrogen peroxide generators available on the market today, which differ significantly in their operating principle: one principle is to minimise surface condensation, reduce corrosion and optimise vapour distribution. The relative humidity inside the safety cabinet must be below 30% in order to ensure that the remaining 70% of the space is filled with hydrogen peroxide vapour.
The other principle is to create trace amounts of condensation for the purpose of sterilisation. The generator will release a number of tiny droplets at high velocity inside the biosafety cabinet.
The hydrogen peroxide vapour is non-carcinogenic but very efficient against micro-organisms. Catalytically, hydrogen peroxide breaks down into air and water without contaminating the environment and without residue. If the biosafety cabinet is ducted, the disinfection process is faster than chlorine dioxide, however, if the biosafety cabinet is not ducted, the hydrogen peroxide must be aerated and that can be time consuming. The time required for the whole 

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