1036 replies to this topic

[Daniel Cooper]

I am glad you acknowledge that N95 masks are effective in filtering out airborne viral aerosols. 

 

 

 

 

Well, to be accurate I only acknowledged that they are more effective than cloth or paper masks, which is a pretty low bar.

 

As far as studies on the cloth/paper masks that were actually used being equivocal - in general when you study something that actually works the effects are usually pretty apparent and you don't get a bunch of studies that show either no effect or a small effect.

 

When antibiotics were introduced, there were no conflicting or equivocal studies on whether they worked. They had a large positive effect that was apparently to anyone that had see their use in the field. All our mask studies either seemed to say they either did nothing or there was a small positive benefit. I'm willing to say they probably had a small positive benefit, but probably quite small indeed.

 

Someone should do a study on N95s vs. the flu or some other upper respiratory virus if it hasn't been done. I'd bet that the effect is better than cloth or paper, but still smaller than you'd hope it would be. But evidence would certainly change my mind.

[Hip]

Well, to be accurate I only acknowledged that they are more effective than cloth or paper masks, which is a pretty low bar.

 

You must surely be aware that in the COVID wards during the pandemic, doctors and nurses were surrounded by infected COVID patients, all coughing and spluttering everywhere. The air in these wards was laden with the COVID virus.

 

The only thing that was protecting the doctors and nurses from catching COVID was their N95 / FFP2 masks, plus their eye protection visors. 

 

If this protection had not worked, the doctors and nurses would have caught COVID themselves, within minutes of entering the COVID ward, and then would be unable to continue their work, as they would have to spend 14 days in isolation. 

 

So if N95 masks did not work, it would have been impossible for doctors and nurses to actually treat COVID patients. The fact that doctors and nurses were manning these wards all the time demonstrates the efficacy of these masks.

 

So I cannot understand anyone who questions the fact that these N95 masks were anything but highly effective. 

 

 

Of course, with the general public in a real world setting, where the masks may not sit tightly on the face, or when people may drop their guard and take off the mask for a while, they may not be 100% effective.

 

But when properly used, these N95 masks work extremely well. 

 

It's only on Longecity, which seems to attract people who doubt all conventional wisdom (probably including the fact that the Pope is Catholic), where people think that N95 masks do not work.

Edited by Hip, 27 March 2024 - 08:46 PM.

[Daniel Cooper]

You must surely be aware that in the COVID wards during the pandemic, doctors and nurses were surrounded by infected COVID patients, all coughing and spluttering everywhere. The air in these wards was laden with the COVID virus.

 

That's good anecdotal information. I hope someone thought to capture data and turn that into a paper.

[Florin]

Poor filtering and/or fit is why non-respirators masks failed.

 

 

 

Those videos were created by idiots for idiots.

 

As has been explained on these threads more than once: the size of the virus-containing water droplets emitted by virally infected people is around 0.1 μm to 10 μm. N95 masks block nearly all particles down to a size of 0.3 μm, and also block a lot of smaller particles down to 0.1 μm. So these N95 masks will trap nearly all viral aerosols. 

 

As for that twit in the Twitter video blowing e-cig smoke through an N95 mask, well e-cigarette smoke particles can be as small as 24–36 nm to 250–450 nm, so can easily pass through an N95. It does not prove these masks don't block viruses. 

 

 

As for that complete moron on the Twitter video, exhaling through a mask on a cold day to create dew, doesn't this halfwit realise that water vapour in the air is a gas, and a gas can easily pass through a mask. The water vapour then turns in visible dew when cooled by the cold weather to below the dew point.

 

AFAIK, N95s should be able to capture particulates of any size, including smoke particulates (see the good filter material/poor fit KN95 mask in the Youtube video above or this technical discussion). The problem with the X video is that the mask was just a crummy cloth mask.

 

Well, to be accurate I only acknowledged that they are more effective than cloth or paper masks, which is a pretty low bar.

 

As far as studies on the cloth/paper masks that were actually used being equivocal - in general when you study something that actually works the effects are usually pretty apparent and you don't get a bunch of studies that show either no effect or a small effect.

 

When antibiotics were introduced, there were no conflicting or equivocal studies on whether they worked. They had a large positive effect that was apparently to anyone that had see their use in the field. All our mask studies either seemed to say they either did nothing or there was a small positive benefit. I'm willing to say they probably had a small positive benefit, but probably quite small indeed.

 

Someone should do a study on N95s vs. the flu or some other upper respiratory virus if it hasn't been done. I'd bet that the effect is better than cloth or paper, but still smaller than you'd hope it would be. But evidence would certainly change my mind.

 

I doubt there will be a real-world, definitive study of respirators versus any respiratory virus any time soon. Study participants (including everyone in their household) would have to use respirators every time they'd go into an indoor space besides their home. This kind of study could have been done during the pandemic, but I doubt there's enough motivation to do anything like that today.

[Dorian Grey]

Problemo with N-95 is, you're never going to be able to require mass adaption all day every day for months or years at a time, without a massive mask police force.  

 

I've worn N-95s at work using the laser on venereal warts, where the smoke carries human papilloma virus that can infect your throat if inhaled.  Yes, we wore them tight to our faces with a surgical mask strapped tightly over to close any gaps.  After an hour or so wearing these, the fatigue would get intense, & you'd be longing for the exits.  Fortunately, a wort ablation is usually over pretty quick.  

 

There are claustrophobic folks who couldn't even keep one of these on their face for 5 minutes without frantically clawing it off to breathe freely again.  These guys would get desperate, and do bodily harm to anyone trying to force them into N-95s for pretty much any reason, for any length of time.  

 

Treat early, with whatever the front line docs see working, and you won't need everyone walking around like robots.  

[Advocatus Diaboli]

Re post # 1022

 

"The only thing that was protecting the doctors and nurses from catching COVID was their N95 / FFP2 masks, plus their eye protection visors."

 

"If this protection had not worked, the doctors and nurses would have caught COVID themselves, within minutes of entering the COVID ward, and then would be unable to continue their work, as they would have to spend 14 days in isolation."

 

Or maybe, for the most part, it wasn't primarily protection that worked. Perhaps it was that the doctors and nurses weren't obese 80 year-olds with comorbidites and age-compromised immune systems?  

[Daniel Cooper]

 

I doubt there will be a real-world, definitive study of respirators versus any respiratory virus any time soon. Study participants (including everyone in their household) would have to use respirators every time they'd go into an indoor space besides their home. This kind of study could have been done during the pandemic, but I doubt there's enough motivation to do anything like that today.

 

I would think you would see a signal just looking at people working in hospitals with masks vs. without masks during their work shifts. Most hospital works will be encountering hundreds of people at work versus a much smaller number off work.

 

Unless the effect is very small and then maybe it would get swamped by the fact that both groups are potentially unmasked during off work hours.  If the effects are that small, probably doesn't matter much anyway.

[Daniel Cooper]

Problemo with N-95 is, you're never going to be able to require mass adaption all day every day for months or years at a time, without a massive mask police force.  

 

I've worn N-95s at work using the laser on venereal warts, where the smoke carries human papilloma virus that can infect your throat if inhaled.  Yes, we wore them tight to our faces with a surgical mask strapped tightly over to close any gaps.  After an hour or so wearing these, the fatigue would get intense, & you'd be longing for the exits.  Fortunately, a wort ablation is usually over pretty quick.  

 

There are claustrophobic folks who couldn't even keep one of these on their face for 5 minutes without frantically clawing it off to breathe freely again.  These guys would get desperate, and do bodily harm to anyone trying to force them into N-95s for pretty much any reason, for any length of time.  

 

Treat early, with whatever the front line docs see working, and you won't need everyone walking around like robots.  

 

Breathing through an N95 can be laborious.

 

And unfortunately, the people that are most at risk from respiratory viruses (the aged, obese, cardiovascular disease, etc. etc.) are going to be the people that will have the greatest issues with wearing one.

[Florin]

Problemo with N-95 is, you're never going to be able to require mass adaption all day every day for months or years at a time, without a massive mask police force.  

 

Nah, if there's enough motivation, almost anyone would wear them. The real problem was that respirators weren't promoted, and a lot of high-risk people were stuck in nursing homes where the staff and visitors didn't wear them. After the vaccine arrived, motivation decreased even more.

 

I would think you would see a signal just looking at people working in hospitals with masks vs. without masks during their work shifts. Most hospital works will be encountering hundreds of people at work versus a much smaller number off work.

 

Unless the effect is very small and then maybe it would get swamped by the fact that both groups are potentially unmasked during off work hours.  If the effects are that small, probably doesn't matter much anyway.

 

There are confounders to studying hospital workers such as HEPA ventilation, not wearing respirators on breaks or outside of covid wards, and not wearing respirators during off-work hours, as you mentioned. So, if a respiratory virus passes some threshold of infectiousness, the rate of transmission wouldn't necessarily be all that different compared to the rest of population.

 

Breathing through an N95 can be laborious.

 

And unfortunately, the people that are most at risk from respiratory viruses (the aged, obese, cardiovascular disease, etc. etc.) are going to be the people that will have the greatest issues with wearing one.

 

Most of those people are able to use even ventless respirators without any issue. If some can't, there's always vented respirators and even PAPRs.

[Daniel Cooper]

Those videos were created by idiots for idiots.

 

As has been explained on these threads more than once: the size of the virus-containing water droplets emitted by virally infected people is around 0.1 μm to 10 μm. N95 masks block nearly all particles down to a size of 0.3 μm, and also block a lot of smaller particles down to 0.1 μm. So these N95 masks will trap nearly all viral aerosols. 

 

As for that twit in the Twitter video blowing e-cig smoke through an N95 mask, well e-cigarette smoke particles can be as small as 24–36 nm to 250–450 nm, so can easily pass through an N95. It does not prove these masks don't block viruses. 

 

 

As for that complete moron on the Twitter video, exhaling through a mask on a cold day to create dew, doesn't this halfwit realise that water vapour in the air is a gas, and a gas can easily pass through a mask. The water vapour then turns in visible dew when cooled by the cold weather to below the dew point.

 

 

I thought that SAR-CoV-2 was about 100nm in diameter. That's right within the range of the 24-450nm for e-cig smoke you quote above.

 

If you assert that all the covid-19 passed through the air is contained within larger droplets then maybe you've got a point, but has that truly been established? I do not think I've personally seen that proof.
 

[Hip]

I thought that SAR-CoV-2 was about 100nm in diameter. That's right within the range of the 24-450nm for e-cig smoke you quote above.

 

If you assert that all the covid-19 passed through the air is contained within larger droplets then maybe you've got a point, but has that truly been established? I do not think I've personally seen that proof.

 

Don't you remember that the COVID prevention measure naysayers were having this precise discussion during the early pandemic, when they started saying that SARS-CoV-2 particles are smaller than the holes in the N95 masks, so masks will not work.

 

It was then that the experts, the people who actually know what they are talking about, rather than the amateur cocky COVID critics and naysayers who are brand new to the subject, explained that viruses ejected from the respiratory tract always come in larger water droplets, comprising mucus or saliva from the respiratory tract. 

 

If like many people on Longecity, you do not trust mainstream science, and want detailed proof that viruses travel inside respiratory droplets, you will have to look for that proof yourself in textbooks and studies. But you may find some useful info in this post of mine from Feb 2020. 

 

Personally I generally trust the consensus view of the scientific community, and trust their view on the efficacy of masks.

Edited by Hip, 01 April 2024 - 07:53 PM.

[Florin]

I thought that SAR-CoV-2 was about 100nm in diameter. That's right within the range of the 24-450nm for e-cig smoke you quote above.

 

If you assert that all the covid-19 passed through the air is contained within larger droplets then maybe you've got a point, but has that truly been established? I do not think I've personally seen that proof.

 

N95 and better respirators can filter any aerosol and even individual virus particles as this technical bulletin explains (which I already linked to in an earlier post).

[Daniel Cooper]

Don't you remember that the COVID prevention measure naysayers were having this precise discussion during the early pandemic, when they started saying that SARS-CoV-2 particles are smaller than the holes in the N95 masks, so masks will not work.

 

It was then that the experts, the people who actually know what they are talking about, rather than the amateur cocky COVID critics and naysayers who are brand new to the subject, explained that viruses ejected from the respiratory tract always come in larger water droplets, comprising mucus or saliva from the respiratory tract. 

 

If like many people on Longecity, you do not trust mainstream science, and want detailed proof that viruses travel inside respiratory droplets, you will have to look for that proof yourself in textbooks and studies. But you may find some useful info in this post of mine from Feb 2020. 

 

Personally I generally trust the consensus view of the scientific community, and trust their view on the efficacy of masks.

 

You'll forgive me but I thought that were wasn't exactly a consensus on whether the main transmission path was free floating viral particles or it is were almost exclusively viral particles contained in droplets. 

 

My impression is that that discussion has gone back and forth a couple of times during the pandemic, but I'll confess that I haven't paid rapt attention to the subject.

[Daniel Cooper]

N95 and better respirators can filter any aerosol and even individual virus particles as this technical bulletin explains (which I already linked to in an earlier post).

 

My understanding is that N95 masks only catch particles in this (~100nm) range because of electrostatic charge due to the fact that the pores in the filter media are actually larger than this.

 

This works pretty well up until the filter media becomes heavily laden with water and water vapor at which point they can no longer maintain electrostatic charge and the efficiency drops off. This works fine say in a hospital setting where mask changes are frequent, but if someone is wearing a mask for an extended time then the efficiency of the filter falls off quite a bit after an hour or so.

 

I have absolutely no doubt that you can get a filter than will consistently catch 100nm particles, but you may have to change the filter frequently or you may need a mechanical (forced air) assist due to media with an inherently smaller pore size generating more resistance to air flow. 

 

As a good friend of mine notes "Time and money put men on the moon" - in other words given the resources and development time you can make almost anything that physics doesn't disallow. So I don't doubt that a filter can be had that will do what you want.

[Hip]

You'll forgive me but I thought that were wasn't exactly a consensus on whether the main transmission path was free floating viral particles or it is were almost exclusively viral particles contained in droplets. 

 

My impression is that that discussion has gone back and forth a couple of times during the pandemic, but I'll confess that I haven't paid rapt attention to the subject.

 

I believe in the very early pandemic, it was thought that airborne transmission of COVID was not common, and health authorities believed the most probable route of transmission was through contaminated surfaces (fomite transmission as it is called).

 

Hence the early advice from the health authorities about frequent hand washing, as it was thought we would be picking up the virus on our hands from contaminated objects that we touched, and then the virus would infect us if we touched our lips, or touched food items we consumed with contaminated fingers. 

 

I understand it is the heavier virus-filled water droplets which eject from our respiratory tract and quickly fall downwards which are the ones that contaminate surfaces. The smaller ejected water droplets, which are light enough to float in the air for a long time, are not much involved in contaminating surfaces, because they do not fall downwards. But these lighter droplets are the ones that you can breathe in, and catch the infection via airborne transmission.

 

I am not actually sure why surface transmission was initially considered the most probable route of transmission. 

 

 

 

Only a while into the pandemic was it realised that airborne transmission was a far more frequent route than surface transmission. So at that point, I seem to remember that health authorities stopped giving out the advice to wash your hands several times a day. 

 

And once it was realised airborne transmission was the major transmission path, obviously masks became more important. 

 

But I saw arguments online from non-experts that N95 masks (or the European FFP2 equivalent) would not work, because the pore size on these masks was larger than the viral particle size, so the virus would get through. But the experts explained that viruses usually travel in water droplets that are much larger than a single viral particle. 

 

 

Edited by Hip, 01 April 2024 - 09:27 PM.

[Hip]

My understanding is that N95 masks only catch particles in this (~100nm) range because of electrostatic charge due to the fact that the pores in the filter media are actually larger than this.

 

I believe the natural Brownlan motion of tiny particles in the air also helps trap them. Due to Brownlan motion, tiny particles do not travel in a straight line, but in a zig-zag path. With such a path, they are more likely to bump into the mask material and be absorbed as they pass through the pores of the mask. 

[Florin]

My understanding is that N95 masks only catch particles in this (~100nm) range because of electrostatic charge due to the fact that the pores in the filter media are actually larger than this.

 

This works pretty well up until the filter media becomes heavily laden with water and water vapor at which point they can no longer maintain electrostatic charge and the efficiency drops off. This works fine say in a hospital setting where mask changes are frequent, but if someone is wearing a mask for an extended time then the efficiency of the filter falls off quite a bit after an hour or so.

 

I have absolutely no doubt that you can get a filter than will consistently catch 100nm particles, but you may have to change the filter frequently or you may need a mechanical (forced air) assist due to media with an inherently smaller pore size generating more resistance to air flow. 

 

As a good friend of mine notes "Time and money put men on the moon" - in other words given the resources and development time you can make almost anything that physics doesn't disallow. So I don't doubt that a filter can be had that will do what you want.

 

Respirators such as N95s are able to catch particulates from the largest sizes of dust down to below the size of any virus (the smallest virus is about 20 nm). There's no particulate size where filtration dips below 95% for N95s. Just read the tech bulletin.

 

If humidity was a concern, there would be explicit instructions about changing filters more regularly, but since there aren't any such instructions, water vapor accumulation is unlikely to be relevant issue. If for some reason you're still concerned, elastomerics and PAPRs don't have this hypothetical issue.