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Masks do help, even (maybe) stopping 75% of influenza, and you can make them

Posted By Jo Nova On March 27, 2020 @ 4:59 am In Global Warming,Microbiology | Comments Disabled

In the West the public have been discouraged from wearing face masks, and told they aren’t much help. This is mostly because they are “much help” and the front line docs and nurses really need them but no one in charge ordered enough in advance, and none of them had the honesty to say so. The daft push-me-pull-you messaging of how the useless masks are needed on the front line will go down as a case study in how not to communicate (or build trust). The truth is we do want people to wear masks in the street, because it almost certainly does slow transmission. (These Lancet authors think so too).

In high density East Asian nations, face masks are common. (And viral growth curves are generally slower, though for lots of reasons.)  Possibly after Coronavirus has gone, masks in winter might be more common here too.

Things can change fast:

Kamil Chudačík, twitter:

In Czech Republic we went from: “Look at the idiot wearing a mask!” to “Look at the idiot not wearing a mask!” in 2 days. I can say the czechs are very conservative in terms of changes so I’m surprised by this behavior.

The DIY mask industry

Medical staff need face masks because they do filter out small enough particles. They reduce the rate of infection. There are scores of papers. And if no medical masks are available, then even home made ones are better than nothing. Right now, teams of home sewers are getting organized, making as many masks as possible. Patterns are being shared online, and since medical masks are running out, some hospitals are even keen to get the home made sort.

In Czechia, a Facebook group called “Czechia Sews Masks” has 33 000 members.

The most useful mask is the one you wear

Another line we are told is that only the N95 (or P2) masks are good enough, but just about any old mask helps.

We’re told plain old surgical masks are just to “stop patients getting doctor germs”. But even these are surprisingly effective compared to the higher quality masks. In 2009 during the swine flu researchers asked parents looking after sick kids at home to take part in a study. The 286 parents were randomly assigned to wear one or none of these masks, mostly they ran out of enthusiasm, with only 25% managing to comply with wearing the mask for five days in a row.  But of those who did wear either type of mask, the rate of getting the flu was about 25% compared to parents who didn’t wear a mask. And surprisingly the N95 mask wasn’t statistically different from the surgical mask, even though the N95 is thicker, and considered to be much better. Of course, it could be that the sort of diligent parents who kept the mask on also had more self-control and were better hand-washers too. But in hospitals where staff do wear masks,  larger studies with 2,000 healthcare workers showed similar results (suggesting that surgical masks were just as good as the N95 masks.) Though in many other studies the N95 masks were more effective. Perhaps it depends on how well they fit. Perhaps most of the benefit is in stopping people touching their face and biting their nails?

 SmartAir Filters has a a really impressive easy-to-read description of different masks, studies, and all kinds of tests — including particle size, and comparison tests of different materials – like tea towels and pillow cases.

Coronaviruses are only 60 – 140 nm in size, insanely small, but masks are still able to filter them out. Though obviously the fit matters and air will easily leak around a poorly fitted mask. But SmartAir also use a fancy “fit-test” machine which can compare the air inside and outside the mask, and that’s while someone was wearing it. It’s a good analysis.

Do-it-yourself mask materials:

Tea-towels were surprisingly good. Double layering them made them theoretically just as good as a surgical mask (apparently). The researchers felt that they were not so easy to breathe through so, so they recommend t-shirt and pillowcase material instead. While they aren’t as effective at filtering, they are more comfortable and more likely to be worn.

Masks, materials, effectiveness.


Even a scarf caught nearly half of all the particles.

Taiwan is making 10 million masks per day.

 Masks are reusable (with care!)  Smartair recommend hanging the mask in the sun for a few hours. So drying it out and leaving it for three days. But do be careful taking the mask off. There are bound to be youtubes to watch on how to do that correctly to minimize the risk of contamination. I”ve heard that is the most risky time.


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