Sterilization of disposable face masks by means of standardized dry and steam sterilization processes; an alternative in the fight against mask shortages due to COVID-19: Letter to the Editor

The Covid-19 pandemic causes imminent shortages of face masks in hospitals globally. In preparation for that scarcity we performed a study to investigate the possibility of reprocessing disposable FFP2 face masks in order to verify their re-usability with a method that could be applied in practice using already available equipment. Therefore single use FFP2 masks (type 1862+3MTM) were sterilized with a 15-minute procedure at 121 ⁰C, using a dry sterilization process as well as with a regular steam process with the masks in sterilization/laminate bags. The effectiveness of these processes are sufficient to inactivate the coronavirus based on the knowledge of inactivation of such viruses. [1,2] A blind comparison of unused sterilized masks was performed with respect to visual inspection, consistency, face fit and breathing resistance. The results of this comparison were that the investigators were unable to distinguish unused new (slightly curved and folded) masks from reprocessed sterilized masks.