EDITOR:

1. Cloth masks are not very effective at preventing infection. In the first randomized clinical trial that included cloth masks, 1,607 health care workers were placed in three groups: Cloth masks, surgical masks, and “normal practice” which included some mask wear and some time without masks. Cloth masks wearers were 2.5 to 13 times more likely to get a clinical-respiratory-infection or influenza-like-infection than surgical mask wearers. The study was performed by faculty of the School of Public Health and Community Medicine, University of New South Wales, Sydney, Australia. The study was not perfect, but randomized clinical trials are the best medical evidence we can get.

2. Surgical masks are better than cloth masks. I have had 40 years of experience wearing surgical masks, not every day, but two to three whole days a week. Surgical masks have a useful life span of 3 to 4 hours. The problem is that exhaled air contains moisture which slowly accumulates on the mask. When the mask gets damp enough, it no longer filters the air, which then exits and enters around the sides of the mask.

3. KN-95 and N-95 masks are definitely better still. KN-95 masks can be fitted by an amateur; N-95 masks must be fitted and tested by a professional to assure a good seal. The manufacturers of KN-95 and N-95 masks state that they are good only for 3 to 4 hours before they need to be “re-processed.” Normal re-processing requires hydrogen-peroxide vapor and ultraviolet light, which I don’t have at home. The manufacturers of KN-95 and N-95 masks state that they can be carefully washed and dried, but they further state that five washes is the limit for these masks.

4. Manufacturers recommend N-95 and KN-95 masks be worn by persons with clean-shaven faces (short mustaches are OK; significant beards are not OK). When I was in the Michigan National Guard (1978-1982), we were all issued M17A1 gas masks to protect against possible Soviet gas attacks. Guard members were required to be clean-shaven. For members who had a skin condition that prevented shaving, medical personnel could issue them a “profile” which really means “medical exception,” and they were allowed to grow a beard up to one quarter inch in length.

5. I am not a COVID nut case. I had COVID October 26-28, 2020. I got vaccinated February and March 2021. I got the booster two weeks ago. I wore the mask every time the governess required it. And I will wear it again if required to do so. But when I look around at the masks people are wearing, I believe that most of them, most of the time, are wearing masks that have no actual effect.

Ralph B Blasier

Escanaba