Reprocessing of PPE in-house or out sourced with Andersen EO Sterilisers

Andersen Sterilisers have been providing sterilisation solutions for over 45 years in UK. Our Ethylene Oxide (EO) sterilisers provide gentle low temperature sterilisation solutions; EO has long been noted for its broad material compatibility. The outbreak of Covid-19 has prompted renewed interest in EO sterilisers and sterilisation services.

The sterilisation effectiveness of EO has been demonstrated against enveloped and non-enveloped viruses, mycro- bacteria and bacterial spores, which represent the most difficult to sterilise micro-organisms. Enveloped viruses such as coronavirus are much easier to inactivate with EO than the bacterial spores used to demonstrate sterilisation efficacy.

Our testing indicates that our EOGas 4 sterilisation does not damage the material or filtration properties of N95 masks after six cycles. We are continuing to extend our testing to 10 sterilisation cycles. The limiting factor for number of processes will likely be the normal wear and tear the masks undergo as they are worn.

Unlike other sterilisation processes, EOGas 4 is compatible with masks and other items that contain cellulose or cellulose-based material.

EO Residuals after processing:

EO residuals for 3 different brands of N95 mask were evaluated using worst-case calculation. The residuals wee obtained after a 24 hour whole device extraction of N95 masks after reprocessing. It is unlikely that a user of PPE would be wearing the same PPE for an uninterrupted period of 24 hours and the wearer wold not have continuous contact with the entire surface of the mask. The residual EO in the N95 masks after 6 hours additional aeration averaged 0.2ꙡg/cm2, whereas the tolerable contact limit 1s 10 ꙡg/cm2 for surface contacting and implantable devices.


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