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Comment by vkou | Hacker News Reader

Do the N95 face masks that you can buy at the grocery even do anything to prevent the spread of coronavirus?

From what I understand n95 masks should work when used properly.

https://www.cdc.gov/coronavirus/2019-ncov/hcp/respirator-use...

I'm not knowledgeable about the efficacy of the masks themselves, but I suspect there's a forest-for-the-trees issue, here. There are at least a few ways to think about whether masks (broadly, or any specific mask) "work"...

- Whether wearing a mask makes it less likely someone will pick up an infection in constant conditions (direct mask efficacy, reduced touching, etc.)

- Whether wearing a mask makes it less likely someone will transmit an infection in constant conditions.

- Whether wearing a mask leads infected people to spend more time around others.

- Whether wearing a mask leads uninfected people to spend more time around others.

- Whether the way masks end up getting allocated in the event of a shortage promotes or inhibits spread at population scale (for example, if masks ended up overallocated towards people who're so concerned that they stay home anyways and away from people who don't have the ability to).

Good questions. You remind me of some of the arguments against wearing a helmet on a bike. In particular, real studies show that automobile drivers are more careful in the presence of bikers without helmets - that is, if you're wearing a helmet, drivers are more careless around you.

Someone texting, driving drunk, or not paying attention is still gonna hurt you more without a helment though.

And sometimes you just fall on your own as well. Out of the few times I’ve met the ground while biking, I’d estimate roughly half to be because I lost balance after hitting a pothole I didn’t see or ice/snow/rain making my bicycle slide. I was glad to have a helmet in these cases.

I'm not making an argument against helmets, partly because I don't know if that effect is large enough to overcome the additional safety of the helmet. I'm just trying to illustrate that sometimes there are non-obvious offsetting effects.

Without getting to far into it, not really.

Theoretically they can... But practically there are so many routes to failure, the average person cannot use it.

If you were the guy with impeccable lab technique... Maybe.

This isn't true. Someone with general intelligence can figure out how to use one of these things correctly, and I think that people who care to figure it out will do exactly that.

This proves not to be the case. Even intelligent people who are not used to wearing a mask will find that they regularly compromise the masks efficacy.

If worn by infected people it can reduce the spread, but if this is the case the infected person should not be around others anyway.

They certainly help people from touching their noses and mouthes, which we do all the time unconsciously and is a vector for transmission.

Apart from keeping you from touching your face, they raise the alarm on those that see you, so they tend to keep their distance.

https://sentido-labs.com/es/biblioteca/coronavirus-2020-02-L...

(Text and video subtitles are in Spanish, but sound is the original English)

N95 masks are complicated to fit properly. For it to work you need a proper seal. The CDC says there is no general sizing guideline and recommends that the fit be tested yearly. I'm unsure how to go about doing this as an inexperienced individual.

Not really, other than limiting spread from someone who is potentially infected and making it harder for someone to touch their face (virus on hands getting into body via eyes/nose).

N95 masks will also limit the spread from someone who is actually infected, too. So the masks will, when used correctly help limit all spread and I am not sure why you say "not really".

But I should add, the CDC only recommends face masks for the infected and limits recommendation of N95 respirators to healthcare providers and those in workplace settings.

People generally aren’t going to use them correctly, aren’t going to change them frequently enough, are likely to touch their face frequently if not used to the mask, and aren’t nearly as concerned about infecting others so much as protecting themselves.

Should you go buy some? Probably jot

My understanding is that the main purpose of the mask is to prevent people who are already infected from coughing and sneezing particulate onto other people.

This is true, but it also prevents you from touching your own face.

That's a surgical mask

No, they do almost nothing once they become moist.

my take on this is that those masks are probably useless, and even if they were useful, most members of the public will not utilize them correctly.

so, i advise people to leave the face masks of all types for utilization by our healthcare workers, as there will soon be a shortage and as a member of the public you should mostly be sitting at home rather than wandering around areas with other people anyway.

The CDC is telling people to use face masks (not necessarily n95 or p100 respirators) when ill or around those that are ill.

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