“Contrary to evidence” Carmel Pine Cone – Sept. 3, 2021
I would like to comment on your article “Alejo asks for new indoor mask mandate” by Kelly Nix.
In your article, Nix refers to an article published in the journal, Physics of Fluids, from researchers at the University of Waterloo. That study investigated the effectiveness of masks in an indoor environment and hence is relevant to this discussion. I have reviewed that article in great detail and want to bring to your attention some important points that the researchers made in their publication.
I will state that the Waterloo article is very well written and the authors clearly document their experimental techniques which are well thought out. As Nix pointed out, K95 and R95 masks can be effective at reducing the transmission from an exhale by 46-60 percent, whereas cloth and surgical masks are far worse, at 10-12 percent. What can be over-looked is that these transmission numbers are for properly fitted masks. A K95 mask may be 46 percent efficient when properly fitted, but that number drops to 3.4 percent when fitted as most people wear them.
While the authors did not measure the transmission of poorly fitted surgical masks, it is logical to assume that the transmission is likely to be worse than the 10-12 percent that they measured for properly fitted cloth or surgical masks.
More importantly, the researchers measured the viral loading in a room with ventilation and found that a properly ventilated room was far superior to wearing masks. By circulating the room air (or perhaps, simply opening a window), you can achieve much lower viral loadings than when the occupants wear masks.
While it is true that a 3.4 percent reduction in viral loading may be beneficial, it may be a distinction without a difference. The authors show that the amount of virus in an unventilated room will saturate over a period of 8 to 10 hours. Under those conditions, all the occupants will be exposed no matter what masks they are using.
In my opinion, Supervisor Alejo is proposing an indoor mask mandate that is contrary to scientific evidence.
Andrew M. Hawryluk, Ph.D., Carmel