Supercritical carbon dioxide-based cleaning and sterilization treatments for the reuse of filtering facepiece respirators FFP2 in the context of COVID-19 pandemic

Supercritical Carbon Dioxide treatment of clean and soiled Filtering Face-Piece respirators is shown to meet mandatory requirements for safe reuse of FFP2. Preliminary tests enabled us to select optimal conditions for Supercritical Carbon Dioxide treatment of FFP2, for one hour at 343 K under 7.5 MPa, with a biocide solution. FFP2s from Paul Boye ' (R) were then tested before and after Supercritical Carbon Dioxide treatment with a soiling solution and a biological indicator (i.e. spores of GeoBacillus stearothermophilus) with respect to three objectives: (i) washing of organic deposits, (ii) sterilization (i.e. spores inactivation) and (iii) preservation of the filtration performances. The proposed Supercritical Carbon Dioxide treatment fulfils these three criterions, with effective decontamination of spores and promising washing preserving FFP2 requirements for filtration efficiency of aerosol ( 94%) with acceptable pressure drop (< 240 Pa). As a simple and low-cost one-step recycling method, Supercritical Carbon Dioxide fits to economical and sustainable development standpoints but also allows one to come back to good practices of face protective equipment use, lowering eventual shortage and tensions for most countries importing these respirators.