As a 50-year-old guy I find it a bit weird to recommend a YouTube channel, but I am going to recommend Aaron Collins’ YouTube channel on masks*. Back in Spring/Summer 2020 we were (rightly I think) urged to avoid the sophisticated masks used by healthcare workers, because there was a shortage of these masks and these frontline workers needed them more. But now there is no shortage, so we should wear the best mask we can. See Aaron Collins’ channel for him testing masks and recommending the best masks. Not all masks are the same, some offer much more protection than others. The filtration properties of cotton fabric are generally pretty poor (colleagues and I have a preprint on that), but the best masks are made from sophisticated filtration medium which is much much better.
There are, roughly speaking, three types of mask: 1) fabric/cloth masks, 2) surgical masks, 3) ones made to a PPE (Personal Protective Equipment) standard. In the UK, the PPE standard is the EU FFP2/FFP3 standard, America has the N95 standard, Korea has KF94, China has KN95 and so on. In a nutshell, masks of type 3) are regulated so you know they offer good protection, 1) and 2) are not so you have little idea if they are good or bad. So if you are wearing a mask, then I would say it makes sense to go for 3) as you know what you have.
Perhaps because I am more vain than I like to think I am, I don’t really like the plain white masks. But that is no problem, I learnt on Collins’ YouTube channel that masklab do masks made to the good FFP2 standard in all sorts of colours and patterns, I have some Spring Fortune ones. The FFP2 test certificate for these masks is here. If you look at page 3 of that certificate you will see values for leakage around 5%**, i.e., 95% filtration. So, for the test aerosol used, they guarantee then when correctly worn, they filter out 95%. The material these masks are made of is a much better filter than cotton fabric. For a cotton mask you’ll be lucky to get 50% filtration efficiency and may get a lot lower – as cotton masks are not regulated you have no way of telling.
Surgical masks are made of material that should be better at filtering than cotton, but the fit is often terrible. There are gaps either side of the mouth and often the nose wire is a bit rubbish so unless you have a tiny wee nose, lots of air will come in and out either side of your nose. A poorly fitting mask is a bad mask: if say 30% of your breath is coming through gaps not through the mask, then 30% is not being filtered. And surgical masks are not well regulated, so as with cloth masks you don’t know what you are getting.
Surgical masks have very little going for them other than being cheap, they are the poor person’s FFP2. You can wear FFP2 etc and surgical masks for I reckon at least tens of hours of normal use***, so a proper mask costing say two pounds is then not a huge expense.
Aaron Collins is in the USA and not all masks he recommends that are available in the USA are easy to get hold of in the UK. But a lot of them are made in Korea, Hong Kong and elsewhere in South East Asia and also available here. And where ever you are, then ideally a mask should meet a good standard, like FFP2 or KF94, fit well and be comfortable.
* Also on Twitter at @MaskNerd.
** The 5% refers to a specific test aerosol, typically an aerosol (= particles suspended in air) of salt crystals with a range of sizes around 100 nanometres. The particles that carry SARS-CoV-2 are probably a bit so are likely filtered a bit more efficiently.
*** Healthcare workers I think only wear them for one shift, but that could be in a ward with COVID-19 patients. I wear mine in M&S and at the university, much lower risk environments, thankfully.
Chance & Necessity 
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