Face masks don’t have to be 100% effective to be useful


The Cochrane review on mask-wearing demonstrates that mask-wearing actually doesn’t make any significant difference, not even N95 masks. It also says that hand-washing only makes about 11% drop in your chances of getting the disease at best.


Cochrane is considered to be gold standard science. My blog was based on common sense reasoning, but it is fairly common for science to contradict common sense, and you should believe the Cochrane Review until such time as they update it with an even better study.

I leave my blog here intact for historic reasons. It demonstrates that common sense arguments do not always represent reality.

There are apparently two sides to the argument on face masks.

One thing all sensible people would agree on is that those health and essential workers on the front line should be prioritized if there is a shortage.

The World Health Organisation said very recently that there is no point in wearing them because there is no proof they stop infection. It has changed its mind and now says that people with the symptoms should wear them. Matt Hancock still insists the evidence they are useless has been very clear right from the start. Sadly, he is still in office, making other poor judgments too, such as threatening to punish the whole class if the one or two at the back don’t behave.

This ‘masks are useless’ side of the argument relies on the fact that viruses are small, whereas holes in thin fabric masks are big. Viruses can pass through them. The tiniest droplets can too, or some of them at least. That is all true. A cheap thin fabric mask will not give you total protection. Accepted. However, I do wonder if advocates of this argument have any idea how breathable waterproof coats work. They block rain, big clumps of water molecules in one direction but allow individual water molecules of water vapour to pass through. Not perfect. You’ll still sweat and get damp, but breathability will help.

The US Centers for Disease Control (CDC) urges all Americans to wear them. Not only that, but to make makeshift masks out of their scarves etc in public transport or supermarkets. The argument relies on the fact that firstly, even a thin porous membrane will reduce the number of viruses a person breathes in, so will reduce the chance of infection, but far more importantly, that they can stop most of the droplets other infected people will give off as the speak, cough or sneeze and therefore greatly reduce the number of airborne particles in an area that are infested with virus. Infected people will emit such infected droplets even before they experience symptoms, so waiting for symptoms to develop means many infected people still infecting others because they weren’t wearing masks. This is all true.

If you sneeze, you probably sneeze into a tissue or handkerchief, both of which are very porous, but it still stops you filling half the room with infected water droplets, and even stops your hand getting soaked. That’s everyday example proof enough – I don’t need to wait for a massive 5-year peer-reviewed study. How many of those saying masks are useless would be happy for you to sneeze of cough in their face without making some effort to use your hanky or even your hand to intercept most of the blast? Zero I think. Not 100% effective for sure, but one hell of a lot better than useless.

So although both sides of the argument are based on truth, you should still wear a mask if there is a big enough infection risk of infecting or being infected. It will reduce the chances of both, and even if the reduction isn’t complete, it’s still sensible. If there is only a tiny risk, you might reasonably judge that the inconvenience isn’t worth the bother. The overwhelmingly important point is that a mask does not have to be 100% effective to be useful. If it’s 50% or 10% it is still useful. The more it can filter out the better, obviously, but even a simple mask will do some good. Keep the best ones for those that need them, but make others available for everyone else asap. Saying they’re useless is just wrong.

3 responses to “Face masks don’t have to be 100% effective to be useful

  1. Ryan Frederick

    Hey Ian,
    I have a futurist project idea to run past you and get your take on. Where’s an email I could reach you at?


  2. Pingback: Futureseek Daily Link Review; 10 April 2020 | Futureseek Link Digest

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