I completely agree. Even having a mask that only results in a 20% reduction of transmission could be the difference between a growth factor that is less than 1, vs a growth factor of greater than one. It could be the difference between taking off or halting.

I suspect that even a spare cotton t-shirt material affixed over the face would stop a significant amount of droplets from transmitting.

It would be worth researching the effectiveness improvised masks, at the very least.

The problem is that a mask that isn't regularly replaced and handled very carefully actually increases your chances of catching the virus, via a mask->hand->face transmission.

Is there data or a study that says that risks increase from using masks poorly? I’ve looked into the literature and everything I’ve seen says they are significantly protective in real-world use.

Wait, how? If it's on the mask wouldn't it be on the face if the mask wasn't there? What process puts viruses on masks but not faces?

The masks encourage a warm moist environment surrounding your nose and mouth.

If the mask becomes contaminated, it becomes an ideal vector for encouraging infection -- so if you touch the inside of the mask with your contaminated hands (say you move the mask to touch your face or adjust it or whatever), for example, the mask becomes the opposite of protective.

Masks are somewhat effective at reducing spread if the already-infected person is wearing the mask.

IMO the biggest problem is people "feel safe" with a mask on, they may not take other precautions.

Also my understanding is that a N95 mask that isn't properly worn (doesn't have a good seal) then it's nearly equivalent to no mask at all.

So you combine those two together and you have people who aren't effectively protected by the mask and are making riskier decisions.

Is this based on data or just a feeling you have?

I have read these comments often now and it's just something people make up to justify not being able to buy masks.

Which part of this is being made up? That improperly fitted mask isn't protective? That unless you very carefully handle a mask when taking it off, you'll transfer the contaminants from it onto your hands and/or face? That people compensate for risk[0]? That those masks are disposable and lose their protective power over short time (hours)?

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[0] - https://en.wikipedia.org/wiki/Risk_compensation

Yes. Do you have a study that shows that a mask that has not been fit tested either provides no protection or actually increases the overall risk to the wearer?

I have looked at a fair bit of research on masks lately, and everything I've seen is that they are significantly protective, and, for example, reduce your risk of catching SARS by about 70%.

Yes, if a mask doesn't fit properly, some air will come through the sides. Even in that case though, the mask is still filtering some air, and it's protecting you from touching your mouth or nose, and it's protecting you from droplets hitting your mouth or nose from being coughed or sneezed on.

The best practice is to not touch your face with your hands. Wearing a mask may increase the frequency you touch your face due to discomfort

Greater surface area, more hand-face contact, and risk compensation.

TL:DR: The most effective use of disposable masks for blocking germ transmission is by the people with the germs who might pass them to this without but at risk.

Surgical masks are meant to protect surgery patients from the medical staff and the droplet-encased germs they emanate. N95 masks are meant to protect the wearer from particulate matter (harmful dust) in the air, specifically those particles over 30 microns. SARS-CoV02 is roughly half the size, so as an aerosolized virion, as opposed to droplet-suspended virions, they may have limited effect. N95 masks also often come with exhalation valve releases to improve inhalation fit - so exhalation pressure does not break the seal around the sides. A sick person wearing a mask with a valve that releases right in front of their mouth may be better than no mask, but it is a potential bypass for droplet suspended virions.

The US just doesn't have the culture where everyone puts on masks during flu season, like some places (HK for one), and that level of herd usage is really what might be likely to slow transmission to a breakable rate.

What I've read about Coronaviruses is that most transmission is either through hand to face contact or droplet-suspended virions so a mask that doesn't protect against aerosolized droplets would still be fairly effective. I understand that surgical masks aren't intended to prevent inhalation of droplets but the substantial symmetry between air passing through one way or the other would suggest at least broadly similar effects either way. Given the empirical results from elsewhere in the thread it seems like that may be the case.

Are surgical masks sealed around the edges? I've only worn N95 before and if you don't have a proper seal you're not even filtering the air. That's what I've always assumed was the problem with surgical masks. It's not that they're not a good enough filter, it's that they aren't even filtering the air when you breath in. But I might be wrong.

> N95 masks are meant to protect the wearer from particulate matter (harmful dust) in the air, specifically those particles over 30 microns. SARS-CoV02 is roughly half the size, so as an aerosolized virion, as opposed to droplet-suspended virions, they may have limited effect.

The N95 filters are tested with particles at 30 microns, but that doesn't say anything about their effectiveness against other particles.

3M, naturally, has released some information on this exact topic [1] which goes into a fair bit of detail on the various methods by which masks effect filtration. The tl;dr version is that there are several ways by which filtration is achieved that generally overlap and work towards providing effective protection well above and below 30um. There is generally a small dip in the transition between two primary methods which creates a specific size range where filtration is less effective.

Whether that's an issue depends on your definition of "limited effect". For the masks they tested, that dip generally occurred around 0.04-0.1um. Even in the worst case scenario, however, the worst masks tested were still filtering ~94% of the particles (in a mask that only claims 95% effectiveness to begin with). The linked document has coronaviruses listed as being about 0.125um in size, which has them falling toward the end of the dip where the mask is trending back towards 100% efficacy.

(For what it's worth, they also have the distribution of droplet sizes in a sneeze and they are all smaller than 30um as well. However they're still in a range where the mask will be about 100% effective.)

Which is all to say I certainly wouldn't describe an N95 mask as being of "limited effect".

[1] https://multimedia.3m.com/mws/media/409903O/respiratory-prot...

And as to that not our culture comment, I mean it's the American of course who got told to isolate himself on suspicion of infection but decided to go to a group political event across state lines regardless, only to infect at least one other person and lead to further isolation calls for everyone else he came into contact with.