Construction and validation of UV-C decontamination cabinets for filtering facepiece respirators: comment.

In their September 2020 paper [Appl. Opt.59, 7585 (2020)APOPAI0003-693510.1364/AO.401602], Purschke et al. report UV-C transmittance measurements of N95 filtering facepiece respirators (FFRs), including the 3M 1860, which is one of the most widely used FFRs. We have also measured the transmittance of this FFR in our two separate laboratories with multiple FFR samples, and we have obtained transmittance values similar to one another, but very different from what Purschke et al. reported for two of the four FFR layers.