Tell us how to correctly don and doff a surgical mask, or a filter, and we can tell you how many steps you got wrong.

This video shows him using bare hands to touch the front of his mask to take it off. https://news.ycombinator.com/item?id=22776002

Literature suggests that 80% of HCP infection is caused by incorrect doffing

https://twitter.com/drbencb/status/1236635924274057216?s=20

https://twitter.com/cmac_evans/status/1236689340123754496?s=...

Because it's so hard we see healthcare settings strongly encouraging "dofficers" / "spotters" -- a second person to watch you taking off your PPE to make sure you're doing it right.

https://twitter.com/heatherevansmd/status/124443236962241741...

https://twitter.com/Dolores_McKeen/status/124432789143070720...

Duffing protocol is very important if your PPE is massively contaminated. I’m not as convinced if you may have been breathed on by a carrier at the supermarket.

That's what the CDC previously said! This post is you agreeing with the CDC.

If you're an HCW, no question, you had better be PPEing up to the max and following donning and duffing procedures to a T. You have huge exposure, and if you screw up, you're very likely to catch COVID.

If the level of risk is so high that I am not legally allowed to leave my house except for specified purposes, you would have to be utterly foolish to think that wearing the best mask available to you is not an utterly obviously correct precaution. You really need to be incredibly gullible to not see this.

If you're not an HCW, in March, as an American, you had about a 1/1000 chance of being a LAB CONFIRMED case of COVID. 1000 people are dying every day of this in America, and the numbers keep going up. If this continues, we will have millions of deaths from COVID.

Being an HCW now is like being a Formula 1 driver. You had better have a crapload of safety gear, and even then your risk is very high. Your chance of dying in a car accident in the next month is roughly 1/500,000. Your chance of dying of COVID next month is perhaps 1/1000. That's 500x the risk of driving. Your argument comes down to "Well, since you're not driving in a Formula One race, there's no need to put on your seatbelt." If you wouldn't dream of getting behind the wheel without a seatbelt, why would you go outside without a mask when the risk is 500x higher?

Most people have someone in their life they can ask to spot them as they practice removing their mask.

Also, wouldn't washing/disinfecting your hands after improper doffing prevent self-contamination?

2. Take off mask.

3. Wash hands thoroughly.

The main point is to wash your hands in between each hand touching things of different contamination levels (eg mask body and back of head).

One's implementation may not be perfect, but it's much better to attempt, practice, and slowly get better - rather than succumbing to do-nothing disinformation being pushed by western governments caught without the will to stockpile and procure enough PPE.

You got the doffing procedure wrong btw.

What "clear science" are you referencing? I have not seen data demonstrating that individual mask use increases the chance of infection, which would be necessary to argue against individuals wearing masks on its own merits. Please share if you have it.

In general, calling something a "conspiracy theory" is fallacious. From what I've seen, the intellectual argument underlying the "no masks" narrative is that individual mask use will "take away" from hospitals. When compared to other countries (eg: https://news.ycombinator.com/item?id=22776614), this is patently ridiculous.

I'm saying that donning PPE is hard, and that members of the public can't do it. They usually miss out several hand washing steps, or they don items in the wrong order, or they don't have a safe place to doff items.

You've said "wash your hands" -- you do that by touching taps/faucets. Most people would have to open a few doors to get to the taps. Now all those door handles, and the taps, are contaminated, so you need to clean them too.

> FWIW I use a 3M 7503 with discrete filters so there is a mask body to grab

The entire front face of that filter is to be regarded as contaminated. You must not touch it when doffing the mask.

People in this thread are claiming that one use of the mask is to prevent infected people from infecting others, but this mask has an exhalation valve, so it doesn't stop infected droplets leaving the person wearing it.

Masks provide marginal benefits to people walking around in public, but only if they're worn absolutely correctly. As soon as people deviate from the rigorous protocols those marginal benefits disappear. Worse, there's a chance that they increase risk. If people are touching their masks but not immediately washing their hands, or they are touching their face to adjust their mask then the mask is causing harm.

> From what I've seen, the intellectual argument underlying the "no masks" narrative is that individual mask use will "take away" from hospitals

WHO, CDC, PHE, etc have all been pretty clear that masks don't provide any benefit to members of the public. This thread is full of paranoid nonsense that this was a deliberate lie by the CDC/WHO to preserve stocks.

And the solution here is to gain experience. I don't "adjust my mask" because I've been using it for household projects for the past few years. My first grocery run with a mask was a month ago. I definitely got to points where I messed up steps or did not have a good plan, but I learned. The best time to start is now.

> Most people would have to open a few doors to get to the taps. Now all those door handles, and the taps, are contaminated, so you need to clean them too.

So then, the same exact situation they're in if they go to the grocery store without a mask? People obviously need to wash their door handles as well.

> The entire front face of that filter is to be regarded as contaminated

The 7503 is the face piece, with my point being that I can grab that part without touching the filters. I have the 2297 filters, which are large round cloth discs - exposed liabilities. The 7093 filters would be better as the filter element is encased in plastic, but alas that's not what I already had.

And yes, it has an exhalation valve which is sub-optimal. I'll try remedying this next time I take the whole thing apart to deep clean it.

> WHO, CDC, PHE, etc have all been pretty clear that masks don't provide any benefit to members of the public

They have not backed up this position with data showing that individual mask wearing is actively harmful, and neither have you. Furthermore, they do recommend that healthcare professionals wear masks, which is inconsistent - if masks are effective against virus particles in a hospital, they can be effective against virus particles in a grocery store.

A basic analysis of the physical system is that all contamination ending up on mask filters would have otherwise been breathed in. So even if all of the filtered virus ends up on someone's hands and is not washed off, that is still better than it being in their airways!

If mask wearing is not actively harmful, then why discourage it at all? The meat of your argument seems to boil down to "you're likely to do it wrong" which is neither scientific nor productive.

Exactly who am I propagandizing? Doctors?

"You wearing a mask is not taking anything away from anyone."

We have a mask shortage in hospitals. You are literally taking masks from people who need them more.

"It is rational protection."

For the medical professionals who need them, yes. For you, it's overkill.

"Many people have (non medical, but N95 or similar) masks sitting in their garage."

They should be donating those to hospitals, ASAP.

*"The best way to protect that healthcare worker is not to give them a mask, it's not to expose them in the first place."

The best way to protect health care workers who do not have masks, today, is to give them masks. The second best way is to stay home. The third best way is to wash your hands. The fourth best way is to not touch your face.

Way, way down the list is "wear a mask", and like the guidelines say, not a medical one.

In March, 1 of every 1000 Americans had a confirmed case of COVID. In April, it might be 1 out of 40. For confirmed cases, given that testing is mostly restricted to people appearing at the hospital, I estimate the fatality rate is 7%. That means that in April, you may have a 0.2% chance of dying from COVID. If you wear a mask consistently, that goes down to 0.02%. If you assume you have 40 years left to live, if you're maskless, COVID will reduce your life expectancy by 1 month. If you have an N95 mask that you wear consistently, COVID will reduce your life expectancy by 3 days. Wearing an N95 mask in April increases your life expectancy by 27 days.

By contrast, wearing a seatbelt over the next month, statistically increases your life expectancy by about 0.2 days. Over the next month, wearing an N95 mask is about 130x more important than wearing a seatbelt.

All of this discounts the massive other benefits from not being infected: No long-term lung damage. All of the people you don't infect because you didn't get infected. No infecting healthcare workers. No contributing to the overload of the healthcare system. Plus, wearing a mask, even if you do get infected, you're much less likely to infect other people, which has a cascading effect.

The point is: If you have access to a mask, it's vitally important that you start wearing it if you go out. Still, don't go out unless absolutely necessary! Minimize contact! Especially for essential workers though like grocery store employees, delivery workers, etc, wear a mask!

OK, cite it.

In fact, this is a meta-analysis of 138 papers from five different databases, and they say right at the top of the abstract that most of the studies were of poor quality:

"Study quality was poor for the three randomised controlled trials and most of the cluster randomised controlled trials; the observational studies were of mixed quality. Heterogeneity precluded meta-analysis of most data except that from six case-control studies."

The table you're citing says that they found an odds ratio somewhat better than frequent handwashing (55%), but worse than wearing a gown (77%) when they averaged the results of five different case-control studies, mostly in hospital conditions (the sixth didn't look at masks). Two studies investigated the use of N95 masks (specifically) at preventing infected people from transmitting their virus to others, and for these studies, they found a .09 odds ratio (with a wide confidence interval: 0.03-0.3), and they go so far as to say:

"Evidence was limited for the superior effectiveness of barrier devices to droplets such as the N95 masks...over simple surgical masks."

So they don't even believe the numbers.

This paper in no way supports the statement you made...in fact, it appears that you completely misunderstood what you read, because the only intervention with 91% effectiveness was "handwashing, mask, gloves and gown combined." But hey...if that's the way you go outside, good for you.

Intervention: Wearing N95 Mask Intervention Effectiveness: 91%.

It's true that handwashing, wearing some kind of mask, gloves, and gown combined is also 91%, but that was not a study arm that specified an N95 mask. Wearing any mask has an intervention effectiveness of 68%. Adding the gloves and gown brings it up to 91%.

What the meta-analysis is saying is that wearing any mask + gloves + gown + handwashing is about the same effectiveness as wearing just an N95 mask. It also supports the idea that "don't touch your face" is probably good advice, but it's also probably not the primary means that SARS spreads. It's probably mostly breathing in droplets that someone just exhaled.

I understood perfectly well what they wrote. They say that evidence is limited for the superior effectiveness of N95 over any mask because the lower confidence interval of N95 and the upper confidence interval of any mask overlap by 5%. Based on the studies they analyzed though, it's likely that N95 is more effective than masks generally. It's also very logical since N95 masks filter better and have less leakage than surgical masks.

I am tired of people like you trying to bend science to their ideology. That is part of what got us into this horrible mess.

I addressed this in my reply: this was based on two studies, both about transmission of the virus to other people. Moreover, the people doing the meta-analysis explicitly say that the evidence for using an N95 mask over a plain-old surgical mask is weak. The confidence interval extends from 0.03 to 0.30...in other words, the evidence is weak.

So basically, this study supports the CDC's guidelines: masks might help prevent you from spreading your infection to others. They don't support your claim ("wearing an N95 mask reduces your chances of contracting SARS by 91%") in any way.

"What the meta-analysis is saying is that wearing any mask + gloves + gown + handwashing is about the same effectiveness as wearing just an N95 mask."

It is absolutely not saying this. It is saying that the combined intervention is dramatically more effective than wearing a mask alone, except for two studies that explicitly talk about transmission. You don't understand what you're reading, and you're spreading misinformation.

It would be nice to have more rigorous studies to support the claim?

Just to be clear, I do think people should wear masks!

Seto 2003w47 13 healthcare workers infected with confirmed SARS within 2-7 days of exposure, with no community exposure

w45 330 probable cases of SARS reported to Department of Health, Hong Kong

For god's sake, this thing is so serious that we're not allowed to go outside for normal activities or go to work. We are all prisoners on very limited work release. If you're not taking extreme measures to protect yourself, you're an idiot.

Here are three doffing procedures specifically for covid-19:

https://twitter.com/EMedSligo/status/1245948283576561670/pho...

https://twitter.com/DisneyBen/status/1245224791122030592/pho...

https://twitter.com/ashaukat09/status/1245169306234769408/ph...

This is supported by your Cochrane review:

> Compliance with interventions—especially educational programmes—was a problem for several studies, despite the importance of such low cost interventions. Routine long term implementation of some would be problematic—particularly maintaining strict hygiene and barrier routines for long periods, probably only feasible in highly motivated environments such as hospitals without the threat of an epidemic.

Something like 80% of infection of healthcare professionals happens during doffing. These are people who are trained to don and doff PPE, and who are supported to do so by their infection control teams. https://twitter.com/drbencb/status/1236635924274057216?s=20 https://twitter.com/NydahlPeter/status/1244875837448638464?s...

You don't need this equipment, and your paranoia is risking the lives of other people who do.