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Why are disposable masks disinfected with ethylene oxide?

Why do masks need to be sterilized with ethylene oxide?

The principle of ethylene oxide sterilization is based on its alkylation reaction with thiol groups (-SH), amino groups (-NH2), hydroxyl groups (-OH), carboxyl groups (-COOH) on protein molecules, as well as with amino groups (-NH-) on nucleic acid molecules. This leads to the alkylation of these functional groups, causing proteins to lose their reactive sites and impeding normal biochemical reactions and metabolism. As a result, microorganisms die, achieving the sterilization effect.

Ethylene oxide is an alkylating agent with strong penetrating power. It can be used for sterilization with various packaging materials and can sterilize items in their packaged state. It can kill a variety of microorganisms (including bacteria, spores, viruses, fungal spores, etc.) at room temperature. It is suitable for biomedically used high-polymer materials that cannot withstand high-temperature treatment, such as natural rubber, polyethylene, polypropylene, and polyvinyl chloride.


The packaging material must have good permeability to air, steam, and ethylene oxide, making it easy to achieve suitable sterilization conditions.

Ethylene oxide does not damage sterilized items, and its strong penetrating power makes it suitable for disinfecting and sterilizing items that are not suitable for conventional methods. For example, electronic instruments, optical instruments, medical devices, fur, cotton, synthetic fibers, plastic products, endoscopes, dialyzers, and disposable diagnostic and therapeutic supplies, among others. Ethylene oxide is currently one of the main methods for low-temperature sterilization.

What does mask analysis mean?

After sterilization, there may be residual ethylene oxide on the mask. Ethylene oxide is a broad-spectrum sterilizing agent, a flammable and explosive toxic gas with a fragrant ether odor. At 4°C, its relative density is 0.884, and its boiling point is 10.8°C, with a density of 1.52 g/cm3. It easily evaporates into a gas at room temperature and can cause explosions when the concentration is too high. Prolonged inhalation of ethylene oxide not only irritates the respiratory tract but also carries a strong carcinogenic potential. Long-term exposure in small amounts can lead to neurosis and vegetative nerve dysfunction.

After sterilization, sterile air filtered through a vacuum air circulation process should be introduced to safely remove residual ethylene oxide, achieving compliance with safety standards. This process is called analysis. Therefore, medical masks sterilized with ethylene oxide must undergo analysis and pass testing before being manufactured and marketed.

In traditional ethylene oxide sterilizers, to put it simply, after sterilization, the toxicity of ethylene oxide needs to be analyzed, which takes 14 days before the product can be released to the market. Now, with the utilization of the physical properties of ethylene oxide, preheating sterilization analysis technology has been developed, shortening the analysis time for masks after sterilization to one day.

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