N95 Filtering Facepiece Respirators Remain Effective After Extensive Reuse During the COVID-19 Pandemic.

In a cross-sectional evaluation of healthcare worker reuse of their own 3M N95 respirators, 83% (76/92) passed the seal check and the fit-test after a median of 40 repeated donnings. The user seal-check had 31% sensitivity to detect N95 respirator failure but 100% specificity.