IUSS sterilizes N95 masks without damaging masks

Editor's Note

In this study from the Houston Methodist Research Institute, immediate-use steam sterilization (IUSS) using a Steris Amsco Evolution HC1500 PreVac Steam Sterilizer autoclave was performed on N95 masks.

Masks were wrapped in paper-plastic sterilization peel pouches (Medical Action Industries 8” role, Ref 422R). A chemical indicator and biological indicator were used for every autoclave cycle.

The 3M 1870 and M3 1870+ masks, which were photographed and fit tested before IUSS and after the IUSS cycle, retained efficacy in a quantitative fit test using the TSI PortaCount Respirator Fit Tester. 

Five test subjects were used to account for individual differences between faces. In all cases, the masks retained their structural integrity and efficacy.

Despite the small numbers in this study, the data provide a valid basis for the use of IUSS for N95 masks, the researchers say. Follow-up studies will be conducted with a significantly larger subject pool from the Houston Methodist Hospital.