In the UK people have been talking about lifting lockdown, with the mandatory wearing of masks in public places. My gut feel is that our government is libertarian in nature, so won’t go near that. They might advise, but I doubt they’ll mandate. “Experts” seem split on whether they are effective or not (the masks, not the government. Everybody is pretty unanimous about the government!) I think it is a case of choose an expert who fits in with what you already think. So one of the questions I have had on my list of things I really need to do, (and sooner rather than later) has been to evaluate the question of just how much use a facemask would be.
I started off, I must admit, thinking: particles small, gaps in the mesh of facemask fibres big, so really did not see the point in wearing one. But I might be changing my mind.
My plan this morning was to find out the size of your average COVID-19 particle, then to research the denier scale, previously encoutered only in the context of women’s tights! My gut feel was that gaps between fibres would be enormous in comparison to the size of this virus.
I ran out of time (I needed to call people) so I never got to find out about Denier. For all I know, it could be the wrong thing entirely. I did have some success, though. My very first hit yielded me a virus size of 0.02 microns. A micron is just 10-6m. That’s actually quite large – okay, well, it’s small, but it is more than a million times bigger than an atom, say, which comes in at roughly 10-15m. Something like my water filter claims to trap particles of that kind of size. If only I could breathe through my water filter, I’d drown instead 😆
Actually the graph that came with that number was interesting. They might have already done the work for me. I don’t own the copyright on any of this, so will just link to their graph and cross my fingers that it stays good.
So the material used to make a surgical mask will filter out 89% of particles which are the same size as COVID. Now, I have no idea who the authors are, how reputable they are, but I thought the image represented a useful start point for later. They at least read as pretty serious.
The thing I picked up from this is that even just a (presumably knitted, common-or-garden) scarf might halve the flow of covid-sized particles. So maybe I will be changing my mind after all about masks.
Probably, more to come on this one.