Why Those Anti-Covid Plastic Barriers Probably Don't Help and May Make Things Worse (nytimes.com) 221
An anonymous reader quotes a report from The New York Times, written by Tara Parker-Pope: Covid precautions have turned many parts of our world into a giant salad bar, with plastic barriers separating sales clerks from shoppers, dividing customers at nail salons and shielding students from their classmates. Intuition tells us a plastic shield would be protective against germs. But scientists who study aerosols, air flow and ventilation say that much of the time, the barriers don't help and probably give people a false sense of security. And sometimes the barriers can make things worse. Research suggests that in some instances, a barrier protecting a clerk behind a checkout counter may redirect the germs to another worker or customer. Rows of clear plastic shields, like those you might find in a nail salon or classroom, can also impede normal air flow and ventilation.
Under normal conditions in stores, classrooms and offices, exhaled breath particles disperse, carried by air currents and, depending on the ventilation system, are replaced by fresh air roughly every 15 to 30 minutes. But erecting plastic barriers can change air flow in a room, disrupt normal ventilation and create "dead zones," where viral aerosol particles can build up and become highly concentrated. There are some situations in which the clear shields might be protective, but it depends on a number of variables. The barriers can stop big droplets ejected during coughs and sneezes from splattering on others, which is why buffets and salad bars often are equipped with transparent sneeze guards above the food. But Covid-19 spreads largely through unseen aerosol particles. While there isn't much real-world research on the impact of transparent barriers and the risk of disease, scientists in the United States and Britain have begun to study the issue, and the findings are not reassuring.
A study published in June and led by researchers from Johns Hopkins, for example, showed that desk screens in classrooms were associated with an increased risk of coronavirus infection. In a Massachusetts school district, researchers found (PDF) that plexiglass dividers with side walls in the main office were impeding air flow. A study looking at schools in Georgia found that desk barriers had little effect on the spread of the coronavirus compared with ventilation improvements and masking. Before the pandemic, a study published in 2014 found that office cubicle dividers were among the factors that may have contributed to disease transmission during a tuberculosis outbreak in Australia. British researchers have conducted modeling studies simulating what happens when a person on one side of a barrier -- like a customer in a store -- exhales particles while speaking or coughing under various ventilation conditions. The screen is more effective when the person coughs, because the larger particles have greater momentum and hit the barrier. But when a person speaks, the screen doesn't trap the exhaled particles -- which just float around it. While the store clerk may avoid an immediate and direct hit, the particles are still in the room, posing a risk to the clerk and others who may inhale the contaminated air. [...] While further research is needed to determine the effect of adding transparent shields around school or office desks, all the aerosol experts interviewed agreed that desk shields were unlikely to help and were likely to interfere with the normal ventilation of the room. Depending on the conditions, the plastic shields could cause viral particles to accumulate in the room. The report did mention a study (PDF) by researchers with the National Institute for Occupational Safety and Health in Cincinnati that tested different sized transparent barriers in an isolation room using a cough simulator. It found that "under the right conditions, taller shields, above 'cough height,' stopped about 70 percent of the particles from reaching the particle counter on the other side, which is where the store or salon worker would be sitting or standing." However, the research was conducted under highly controlled conditions and took place in an isolation room with consistent ventilation rates that didn't "accurately reflect all real-world situations," according to the study's authors. It also "didn't consider that workers and customers move around, that other people could be in the room breathing the redirected particles and that many stores and classrooms have several stations with acrylic barriers, not just one, that impede normal air flow."
Under normal conditions in stores, classrooms and offices, exhaled breath particles disperse, carried by air currents and, depending on the ventilation system, are replaced by fresh air roughly every 15 to 30 minutes. But erecting plastic barriers can change air flow in a room, disrupt normal ventilation and create "dead zones," where viral aerosol particles can build up and become highly concentrated. There are some situations in which the clear shields might be protective, but it depends on a number of variables. The barriers can stop big droplets ejected during coughs and sneezes from splattering on others, which is why buffets and salad bars often are equipped with transparent sneeze guards above the food. But Covid-19 spreads largely through unseen aerosol particles. While there isn't much real-world research on the impact of transparent barriers and the risk of disease, scientists in the United States and Britain have begun to study the issue, and the findings are not reassuring.
A study published in June and led by researchers from Johns Hopkins, for example, showed that desk screens in classrooms were associated with an increased risk of coronavirus infection. In a Massachusetts school district, researchers found (PDF) that plexiglass dividers with side walls in the main office were impeding air flow. A study looking at schools in Georgia found that desk barriers had little effect on the spread of the coronavirus compared with ventilation improvements and masking. Before the pandemic, a study published in 2014 found that office cubicle dividers were among the factors that may have contributed to disease transmission during a tuberculosis outbreak in Australia. British researchers have conducted modeling studies simulating what happens when a person on one side of a barrier -- like a customer in a store -- exhales particles while speaking or coughing under various ventilation conditions. The screen is more effective when the person coughs, because the larger particles have greater momentum and hit the barrier. But when a person speaks, the screen doesn't trap the exhaled particles -- which just float around it. While the store clerk may avoid an immediate and direct hit, the particles are still in the room, posing a risk to the clerk and others who may inhale the contaminated air. [...] While further research is needed to determine the effect of adding transparent shields around school or office desks, all the aerosol experts interviewed agreed that desk shields were unlikely to help and were likely to interfere with the normal ventilation of the room. Depending on the conditions, the plastic shields could cause viral particles to accumulate in the room. The report did mention a study (PDF) by researchers with the National Institute for Occupational Safety and Health in Cincinnati that tested different sized transparent barriers in an isolation room using a cough simulator. It found that "under the right conditions, taller shields, above 'cough height,' stopped about 70 percent of the particles from reaching the particle counter on the other side, which is where the store or salon worker would be sitting or standing." However, the research was conducted under highly controlled conditions and took place in an isolation room with consistent ventilation rates that didn't "accurately reflect all real-world situations," according to the study's authors. It also "didn't consider that workers and customers move around, that other people could be in the room breathing the redirected particles and that many stores and classrooms have several stations with acrylic barriers, not just one, that impede normal air flow."
It's all about giving people confidence (Score:5, Interesting)
I had presumed that many of the measures where not directly effective, but certainly helped calm the more risk averse members of society, and give them confidence that they were not alone, and things were being taken seriously. So, the effectiveness of barriers should I think be more to do with whether people feel safe in spaces where barriers are being used.
We're still (globally) unsure how to deal socially with barriers, masks etc. When is it right to wear a mask, when is it unacceptable to not.
Re:It's all about giving people confidence (Score:5, Insightful)
people feel safe in spaces where barriers are being used.
Making people feel safe when they are not is harmful.
People feel safe in the checkout lane because there is a barrier between them and the cashier, but they really should be using self-checkout or home delivery.
Re:It's all about giving people confidence (Score:5, Insightful)
people feel safe in spaces where barriers are being used.
Making people feel safe when they are not is harmful.
People feel safe in the checkout lane because there is a barrier between them and the cashier, but they really should be using self-checkout or home delivery.
Another thing is that these barriers are also obstructing sound. I've had plenty of occasions where a clerk has told me my check-out total is "mumble dollars and mumble cents and would I like mumble to mumble my mumble." That's the bit where I have to lean in or slightly around so they can point their mouth-canon at mean and speak up. I'm then more at risk than if I could have stayed five or six feet back and they just talked normally.
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They certainly have not raised voices to compensate. A little grille with angled vents would let sound through and still block large projectile particulates. But cutting holes in cheap plexiglass is not easy and most barely scrapped together what they have with the wrong tools already.
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The problem with self checkout is that the checkout itself is probably covered in COVID. Most of them are touch screens and often don't work with pointing devices (I use a brass key shaped thing).
I usually use the self-scan hand-held devices. They sanitize them before putting them on the shelf and there is usually a sanitizing station nearby so I can give it an extra clean. I use disposable gloves too. Unfortunately the checkout still requires using the touchscreen and it doesn't work with gloves, but at le
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I use disposable gloves too.
Wearing gloves is only useful if it's easier to remove the gloves than it would be to wash/sanitize your hands, which is almost never true outside of a doctor's office or hospital. The virus isn't absorbed through the skin, and gloves spread the virus just as much as skin does.
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I usually pull them off carefully and throw them away. It's wasteful though so maybe washing is a better option. Problem is at the supermarket all you have is bottles of sanitizer you bring with you, and I don't really trust them.
My wife uses re-usable gloves and is careful when removing them, and she uses industrial quantities of sanitizer on them at every opportunity.
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Most of what I have read indicates the likelihood of COVID transmission from touching surfaces is pretty low. It is higher for some other flu-like illnesses, which no one wants either. But you won't become infected with any of these by getting them on the skin of your hands only, and if you've not built the above habit you are just as likely to touch parts of your body that a
Easier said than done (Score:2)
> Why not just build the habit of not touching your eyes, mouth, nose, ears, open wounds unless you've recently sanitized your hands?
That would help. A public health person was talking about that in a news conference - while sub-conciously touching her face repeatedly. I'm sure she was quite surprised to discover that she had touched her face a dozen times while talking about not touching your face.
So it's a good thing to do, and not the least bit reliable.
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The food is mostly in packaging. My understanding is that COVID can't survive outside the body for up to 72 hours but usually much less, so by the time I get to opening the packaging if there is any inside it's probably long dead. Fresh stuff I wash of course, not perfect but again it usually gets left alone for at least a day before being eaten so the virus probably wouldn't survive on it anyway.
As for the brass key thingy I keep it in the car. Brass as well known anti-viral properties. For some reason vir
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And your best defense against Covid in this scenario is likely to be the immune system challenge from the small amount of infection you get from these very actions.
Idiots like you are the reason we can't have nice things.
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Making people feel safe when they are not is harmful.
Sure, but its profitable. Business only has a duty to make profit.
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Oof. Please, no! As someone who has gone to the grocery store during this time, those Instacart folks just make it worse for everyone else. Barreling around corners like their shopping cart is some kind of rig in a Mad Max movie. Blocking vast sections while they scan and bag their various items. Clogging up isles and crashing into me because they're too busy looking at their phones (ok, this last item is true of regular shoppers, but they seem to at least apologize when they notice).
Of course, that just d
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We knew they were ineffective by around May 2020. Japan had just build a new supercomputer and used it to simulate the effects of various barriers on virus-carrying particles emitted from the mouth and nose. They found that these plastic barriers do very little to protect you.
Re:It's all about giving people confidence (Score:5, Insightful)
I had presumed that many of the measures where not directly effective, but certainly helped calm the more risk averse members of society, and give them confidence that they were not alone, and things were being taken seriously. So, the effectiveness of barriers should I think be more to do with whether people feel safe in spaces where barriers are being used.
We're still (globally) unsure how to deal socially with barriers, masks etc. When is it right to wear a mask, when is it unacceptable to not.
Yet there's views, reports, and even books on the subject that the psychological effect they were seeking was to increase fear.
Whether increasing fear is a "good" thing or not is open to debate. Fear denier!! People weren't so much following the science on viruses, but following the science on psychological manipulation.
As another comment points out, giving people a false sense of security is harmful.
Likewise, censorship of ideas, telling scientists who have some data that they are being "misleading", and all that, is harmful to society and science.
There's a lot of stuff we've been doing which is irrational, unjustified, and in the end, just kinda bad. This includes the attitude of trying to make everything highly polarised and divisive. There's plenty of shit that we just don't understand well or know much about, but leadership continues to get all black and white and absolutistic.
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Back during Columbine, the same justification was given for every absurd measure by every petty tyrant, and was used as an effective cudgel against the least unable to assert themselves (namely kids, and even more every social outcast).
Same was given in the aftermath of 9/11, where every prejudice against swarthy people was justified in the name of "being safe".
It is a race to the bottom driven by the most neurotic. No good can come of it.
Re:It's all about giving people confidence (Score:5, Interesting)
I think the only unacceptable time to wear a mask is when you're being required to identify yourself to a government institution, so for example, your passport or driver's license photo, or if a police officer comes up to you and requests to verify your identity.
Any other time is perfectly allowable for any reason unless there are rules stating such.
Masking up is extremely common in Asia since the SARS outbreak 20 years ago and it wasn't unusual to see people wear masks when they were feeling a little ill. In some countries, it's almost always.
It's why the Hong Kong protestors all wore masks - it was perfectly legitimate and socially acceptable to wear a mask. It's why China had to outlaw the practice because it was interfering with their facial recognition systems, other then if you're sick, of course. (And a wave of hypochondria sweeps Hong Kong).
In places where they don't want you to wear a mask, they normally have signs saying so. But then again, they also usually also say things like no masks, no helmets, no sunglasses, or anything else that could obscure your identity. And those signs were usually in front of banks and a security guard would make you remove your mask/helmet/sunglasses/etc. (Yes, a number of people just leave their motorcycle helmets on when going about their day to avoid taking it off and having to carry it - if you're only going to be there for a few minutes).
And yes, I've noticed over the past decade or so. more of my Asian coworkers often wore masks to the office when they were sick.
I think what might happen these days is a normalization of mask wearing - whether you're sick, or you just want some privacy from surveillance cameras and facial recognition systems and such.
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Well, also in many countries there are laws that forbid wearing masks in demonstrations.
At least here that law was caused by many incidents where some masked anarkists joined normal demonstrations and tried to cause trouble.
Re: It's all about giving people confidence (Score:2)
We're still (globally) unsure how to deal socially with barriers, masks etc. When is it right to wear a mask, when is it unacceptable to not.
Bullshit. Much of the world has zero social issue with masks. If you're sick, or there's a pandemic, you wear one and nobody thinks twice about it. A good chunk of the world is still trying to figure out how to socially deal with women who aren't covering their faces.
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So you're saying it's all virtue signaling and medical theater?
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How is this a troll? He's mostly correct. Cloth masks rarely fit correctly and are nowhere near as effective as N95s.
Re:It's all about giving people confidence (Score:5, Informative)
How is this a troll? He's mostly correct. Cloth masks rarely fit correctly and are nowhere near as effective as N95s.
Because good-quality cloth masks are still good enough to make a significant difference, especially in moderate-exposure environments, such as grocery stores. One experiment I read about last year tested a bunch of different qualities and combinations of fabrics. A single layer of loose cotton wasn't all that helpful (something like 10% effectiveness), but multiple layers of different fabrics (I think one combination was a layer of cotton and a layer of silk) could get up over 90% effectiveness.
There are some numbers between 0% and 100% (Score:2)
N95 masks, used correctly, provide nearly 100% protection.
A cloth mask is only half as effective. It only cuts your chances of getting covid in half.
Re:It's all about giving people confidence (Score:5, Informative)
We have known for a long time now that mask mandates that include cloth/paper masks (non-N95) are essentially futile with this virus.
Have we really? Citation, please. My understanding several months into the pandemic was that even a reasonably-well-fitting two-layer fabric mask offered worthwhile protection for both the wearer and other people in the same breathing space. Covid is a numbers game - the amount of initial viral load can a) make the difference between contracting Covid and not, and b) be a determinant in how severe the illness is. This works in both directions, i.e. inhaling and exhaling. Such a mask is useless in a hospital setting where exposure levels can be high and constant, but for everyday use my understanding is that it can make a worthwhile difference.
To date I have heard and read nothing that contradicts what I just said, so if you have credible sources please cite them.
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They are ignoring the obvious evidence for wearing a mask because they don't want to wear one anymore, it is as simple as that.
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Here's your Citation(s): https://wwwnc.cdc.gov/eid/arti... [cdc.gov]
"we conducted a randomized controlled trial to compare the efficacy of cloth masks with that of medical masks and controls (standard practice) among [1607] healthcare workers in Vietnam. Rates of infection were consistently higher among those in the cloth mask group than in the medical mask and control groups. This finding suggests that risk for infection was higher for those wearing cloth masks. The mask tested was a locally manufactured, double-lay
Re:It's all about giving people confidence (Score:4, Informative)
That (2015) study does NOT says that cloth masks are ineffective, only that they are less effective than other types.
This is from 2021 (short version: masks work):
https://www.cdc.gov/coronaviru... [cdc.gov]
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That (2015) study does NOT says that cloth masks are ineffective, only that they are less effective than other types.
This is from 2021 (short version: masks work):
https://www.cdc.gov/coronaviru... [cdc.gov]
There are some pretty legitimate criticisms of those kinds of retrospective analyses. The biggest of which is the massive amount of confounding factors. It's pretty easy to imagine that when you're sampling "rigorous adherents" to mask wearing your biasing your population heavily towards individuals taking other precautions (social distancing, restricting activities, etc.). Additionally, we know that the virus has to date been driven by "super spreaders" with abnormally high viral loads and presumably ot
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This study only speaks to the efficacy of cloth masks vs medical-grade masks. It it silent on cloth masks vs no masks.
In other words.. this study is useless for this discussion.
The control arm was ‘standard practice’, which comprised mask use in a high proportion of participants. As such (without a no-mask control), the finding of a much higher rate of infection in the cloth mask arm could be interpreted as harm caused by cloth masks, efficacy of medical masks, or most likely a combination of both.
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You must have missed the part where the authors said:
"Medical and cloth masks were used by some participants in the control group, but the poor performance of cloth masks persisted in post hoc analysis when we compared all participants who used medical masks (from the control and the medical mask groups) with all participants who used only a cloth mask (from the control and the cloth mask groups)"
Re:It's all about giving people confidence (Score:5, Informative)
Again.. this is just saying that cloth masks are worse than medical masks. It doesn't say that cloth masks are worse than no masks.
The study is all about which types of masks *health care professionals* should use.
Conclusions
The filtration, effectiveness, fit, and performance of cloth masks are inferior to those of medical masks and respirators. Cloth mask use should not be mandated for healthcare workers, who should as a priority be provided proper respiratory protection. Cloth masks are a more suitable option for community use when medical masks are unavailable. Protection provided by cloth masks may be improved by selecting appropriate material, increasing the number of mask layers, and using those with a design that provides filtration and fit. Cloth masks should be washed daily and after high-exposure use by using soap and water or other appropriate methods.
Emphasis mine.
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Again, they had a control group. They compared medical masks, cloth masks, and no masks:
"The rate of CRI was highest in the cloth mask arm, followed by the control arm, and lowest in the medical mask arm. The same trend was seen for ILI and laboratory tests confirmed viral infections. In intention-to-treat analysis, ILI was significantly higher among HCWs in the cloth masks group (RR=13.25 and 95% CI 1.74 to 100.97), compared with the medical masks group. The rate of ILI was also significantly higher in th
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"It is important to note that some subjects in the control arm wore surgical masks"
from the study author's 2020 comment:
https://bmjopen.bmj.com/conten... [bmj.com]
Also from that comment:
"Our research does not condone health workers working unprotected. "
Re:It's all about giving people confidence (Score:5, Informative)
Again, they had a control group. They compared medical masks, cloth masks, and no masks:
No. The control group was definitively *not* "no masks"
The control group was "standard practice". I repeat, from my first response (from the "Strengths and limitations of this study" section at https://bmjopen.bmj.com/conten... [bmj.com]):
The control arm was ‘standard practice’, which comprised mask use in a high proportion of participants. As such (without a no-mask control), the finding of a much higher rate of infection in the cloth mask arm could be interpreted as harm caused by cloth masks, efficacy of medical masks, or most likely a combination of both.`
They *did not* have a "no mask" control group.
Re:It's all about giving people confidence (Score:4, Insightful)
Interesting moderation today..
Basically correct, but with couple of minor notes/nitpicks.
1) There are few outdoor situations where a mask will be useful, basically places where people cannot maintain distancing. If everyone is packed together then people will be breathing on each other.
But yes in most outdoor situations the natural airflow will be way more effective than a mask.
2) There is also another scientific mask: the surgical mask. It is not as effective as a N95 mask, but definitely scientifically proven to help against transmission of viruses. That is why they have been used in medical settings for quite a long time already.
Oh you're exempt? (Score:3, Funny)
"Why are you exempt?"
"Asthma"
"It has been proven that several masks at once do not restrict your breathing by both doctors and amateur athletes. Next excuse."
"I have trauma from being raped."
"Well if you get covid you can deal with the trauma of getting deepthroated by a plastic tube. Next excuse."
"I have autism."
"While I understand, the safety of society is more important than your needs. Next excuse."
"I have recovering burn marks on my face."
"Okay that's actually a viable excuse, but you should stay indoors until it heals in that case. Next excuse."
"I chopped my ears off."
"You can use a paper clip to secure the mask or wear a bandanna. Next excuse."
"I have a card that says I'm exempt."
"And I have a card that says I own a plot of land on the moon but NASA laughs at my littering fines. Next excuse."
"I think the pandemic is a hoax."
"Less oxygen to your brain wont do any more damage than it already has from moonshine and meth. Next excuse."
"I have the right to not wear one."
"No you don't. Next excuse."
WTB the doxx of all antimaskers.
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My store, my rules. You wear a mask or you shop somewhere else.
Yes, it is that simple.
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I was held up in line for ten minutes last wednesday because someone in front of me was demanding a cashier that was wearing a mask. Three people eventually just left the line and gave the cashier the stare of death and one gave the finger. I just wanted some 7-Up, JFC.
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I think that depends on the country. In mine, the whole masquerade is mandatory, so it's fairly easy for stores to tell these morons to put a damn mask on because else the store could face fines up to the point of them getting shut down.
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"My Licensed-Restricted Landlord-approved Zone-controlled Franchise"
Its still as simple as any other dress code enforced by your franchise, I don't get the point you are trying to make.
Re:Oh you're exempt? (Score:5, Insightful)
For many of them it is just, "If I wear a mask I don't feel macho."
Same as when I worked in a factory and morons would work with dangerous chemicals without a mask.
I told the boss, "I'm happy to do that job, but I need a safety mask."
"No you don't, it's not dangerous."
"The label says it can kill me."
"No it doesn't."
"Check the MSDS."
"OK lets go look a the label on the barrel, you'll see; you don't need a mask."
So we walk to the shack, outside the building, where they store the chemical... because it is dangerous... and the label has a big skull and crossbones "DO NOT INHALE, RISK OF DEATH."
So then he agrees to requisition a mask, but he says, "I don't think it is such a big deal though, Chuck does it without a mask all the time."
"Yeah, but Chuck is also a moron, and I'd like to keep my brain cells."
But if the Big Boss is coming around, and they're forced to wear their safety equipment... they whine and cry and whine and cry about it being too hot, too sweaty. Oh, cry me a river "macho man." A bunch of idiot wusses who are just scared of looking like they care about themselves, because what Manly Man cares about himself?
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So they were so macho, they couldn't take a little heat and sweat from the gear? Sounds like they were more like wimps who complain a lot rather than work through it like a real macho m
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Real men don't bring up their manliness.
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Re:Oh you're exempt? (Score:4, Insightful)
Idiot Management.
At a play I once worked at I refused to bypass the safety circuits to work in the electrical cabinet on a live 3 phase brakepress. We can't shut it down says manager as we will lose production for 30 mins while you do your job. I still refused so the manager got all angry and pushed me out of the way, bypassed the interlock circuit so he could open up the cabinet and then stuck his hand in. A second later his is on the other side of the room unconscious and did not come back to work ever.
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Comment removed (Score:4, Insightful)
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No, the real answer (and the one recommended by actual lawyers) to "I'm exempt" is "Then give me a list of what you need, and we'll gather it up while you wait in your car."
It's amazing how exempt people suddenly aren't any more when you respond with something that's actually legal and inconveniences them.
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Logic isn't welcome here.
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Over 600,000 dead so far. Including this genius https://www.nbcnews.com/news/u... [nbcnews.com]
Dead because of the vaccine approval strawman.
Re: Oh you're exempt? (Score:4, Informative)
It has 99.9% survival
You might want to check your math. In the US, 0.2% of the total population has already died from COVID-19. Unless you're suggesting that every person in the US has already gotten it twice?
I'm tired of being... (Score:5, Funny)
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But of course only 'til football season starts again, then I'll be back to being a coach.
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Rugby [wikipedia.org] changed from "ball in hand" to "no ball in hand" which makes it more like "soccer". [wikipedia.org]
Re: I'm tired of being... (Score:2)
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...an infectious diseases expert. I'm going to be an expert on Afghanistan instead now.
Versus all the experts on the border and trade policy from three years ago? Or the experts on Russia?
Provides concrete support for what we know (Score:4, Insightful)
Given our collective pandemic experience over the past 2 years, the study underscores what should now be common sense. Nothing here that we did not know already.
Barriers work but not in isolation of other measures and only if implemented correctly without interfering with ventilation or distancing.
To create significant reduction of transmission masks are still the primary barrier. Ventilation, social distancing are in the top three effective methods of pandemic control. Barriers prevent direct transmission of heavy droplets (sneezes) but do not prevent micro droplets which stay airborne for significant periods of time.
Face shields without a mask, chin masking, invading personal space, etc, are ineffective or defeat efforts to reduce transmission.
What seems to be missing are effective public information campaigns that pull this knowledge together and promote public compliance. Instead we get all sorts of posturing by public figures who would rather win a popularity contest instead of dealing effectively with public health issues. This is not a swipe at any particular politician or party. I have not been impressed by any of our leaders (Canada). They all equivocate and none of them have demonstrated exemplary leadership.
Aw fuck, I'm ranting again.
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I wouldn't be surprised if the kind of non-medical cotton face coverings pushed by mask policies in most countries have the exact same problem. The article is all about how barriers stop the larger particles produced by coughing or sneezing but not the finer aerosols that supposedly are responsible for most of the spread; this is exactly what you'd expect non-medical masks with relatively coarse pores and no filters to let through. Masks have just become a partisan battleground in the US which means there's
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Non-aerosol droplets (10 microns) that are captured by low-grade masks will otherwise evaporate and turn into aerosols before they hit the floor. That's the primary mechanism of cotton masks helping against outbound transmission, although it depends on temperature and humidity.
And there is the well known case of the two infected hairdressers that did not infect any of their 139 clients. Cotton masks on the hairdressers, various masks on the clients.
https://www.cdc.gov/mmwr/volum... [cdc.gov]
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Barriers work but not in isolation of other measures and only if implemented correctly without interfering with ventilation or distancing.
Do they though? I'm struggling to understand why they would. I can see they might stop droplets if someone sneezes at me. I don't see why particles which float wouldn't just float over and around the barrier.
I've assumed for the last year these were measures we put in place in a panic 18 months ago because we didn't know better (and better safe than sorry). Now they seem kind of futile and pointless and we just need someone to say the emperor is wearing no clothes.
Science shows that our intuitions are wrong. Again (Score:3)
Humans accumulate life experience and draw on it to assess the new situation they face. Sadly sometimes that experience points in the wrong direction, and this appears to be such an example; invisible aerosols don't do what we expect. Any research that shows us more of how the world actually works is good, but does upset people who are too confident in their current beliefs.
A deeper problem is that sometimes the science proves incorrect; the WHO and CDC's denial of the air borne transmission of Covid for many months is a fact that should make us hold 'science's' claims with some scepticism. OTOH there isn't a rational alternative... Well - it makes life interesting, as in the curse 'May you live in interesting times', which Terry Pratchett had so much fun with https://en.wikipedia.org/wiki/... [wikipedia.org]
Aerosols (Score:4, Informative)
If you can smell cologne or smoke through your mask, you can be infected with the virus, too. Aerosols are much smaller than you imagine. This is also why setting up barriers to air flow can concentrate the virus.
Re: Aerosols (Score:2)
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Covid-19 is the disease, SARS-CoV-2 is the virus. Covid-19 is named for 'corona virus of 2019'.
The disease is named after the virus, and somehow the virus is named for the disease, 'severe acute respiratory syndrome coronavirus 2'.
And I agree, it should probably get a new name, but only after we get it a new naming body [ictvonline.org].
Re: Aerosols (Score:2)
A particle doesn't need to be smaller than an aerosol droplet to be carried by them. The atmosphere is full of these particles, mainly dust, sulfur, volcanic ash and air pollution. A virus is 2,000 times smaller than a dust mite, but mites are everywhere. So too, viruses.
So the mitigation is not to try and prevent infection, a lost cause, but to prevent serious injury and death. That's the real value of a vaccine. Masks are security theater.
Re: Aerosols (Score:2)
Re:Aerosols (Score:5, Informative)
Gaseous fragrance molecules are not aerosols. If you want to filter those, you need an activated carbon filter. Volatile molecules: 1 nanometer. SARS-CoV-2 virion: 100 nm. Virion plus dried-up mucus and salt from a droplet: even larger.
Cigarette smoke is a mixture of aerosols of the hardest kind to filter (0.1-1 micrometers) and vapors (gas). You can still smell cigarette smoke after it has passed through a particle filter due to the gas-phase compounds, but it smells very different compared to unfiltered smoke.
Re: Aerosols (Score:3, Insightful)
Cloth masks are ludicrously ineffective given these particle sizes and transmission mechanisms. If the deal was "everyone must wear N95 masks" that might be an arguably reasonable position. But cloth masks? No way. That's just theater.
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That's why the focus should be on blocking outbound droplets rather than trying to solve inbound aerosols (which requires more like an N95).
Yet another one (Score:3)
Yet another article saying "X doesn't protect us 100% from COVID, so why bother? It gives people a false sense of security". Where X has been masks, travel restrictions, plastic dividers, closing shops and who knows what else.
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Not really? The article seems to indicate that, as implemented, most of these barriers are completely ineffective against transmission. In some cases they may put your coworkers at greater risk by limiting dispersal.
So which is it? (Score:2)
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"It" is a virus. If your mouth sprays out droplets, some of that will evaporate down quickly to aerosol in size in the air. Masks are effective at preventing droplets from becoming aerosols, but not effective at keeping you from breathing aerosols in. That's why they don't protect the wearer very much. They protect everyone else.
Re: So which is it? (Score:2)
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Viruses are just viruses. They do not "become" aerosols. They all weigh about the same amount so their ability to be carried by a particular droplet or aerosol size is not going to change much.
Re: So which is it? (Score:2)
Employee safety (Score:4, Interesting)
Those barriers are pretty effective at preventing customers from spitting on, getting in the face of, throwing things at, grabbing or hitting the employee. Yes, they can be knocked down by a determined customer, but they impose a sense of separation and safety from the increasingly deranged masses.
Next: seat-belts cause injuries in road accidents (Score:5, Interesting)
It appears that barriers intended to prevent airborne transmission of diseases might actually make things worse --- sometimes. I am sure it is possible to come with cases where injuries occurred related to wearing a seat-belt in a road accident. But I am pretty sure you can come up with far more cases where injuries occurred due to not being protected by a seat-belt.
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The difference with seat belts is that any time a seat belt causes an injury, it prevents a far worse injury. Would you rather have a broken collar bone or a steering column embedded in your chest?
Probably depends on how expansive ... (Score:3)
There's a Chinese food takeout place near my house that has completely walled off the customer/pickup area from the employee/register/kitchen area with plexiglass and they have a small double-door airlock for money exchange and a larger one for food. Looks a little startling when you first see it, but seems pretty solid barrier-wise.
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Chinese Restaurants and Covid (Score:2)
Around here, "all" the chinese restaurants have implemented such a similar policy like you have described that I wonder if somebody ran a workshop, or they were all talking to the same person(or own by the same company/family on the backend). Before that, the stores were the hardest shut down of the restaurants.
Anyways, at least in my area the customers now stay outside, so you effectively never enter the store. So I'd rate that barrier as "Very good"
Speaking strictly for myself... (Score:2)
Obviously. (Score:3)
The Actual Research Results (Score:3)
Johns Hopkins Study: [bolding by me] "By contrast, closing cafeterias and playgrounds and the use of desk shields are associated with lower risk reductions (or even risk increases); however, this may reflect saturation effects because these are typically reported along with a high number of other measures." In other words, the "odds ratio of COVID-19–related outcomes" for using desk shields was only increased "compared to the reduction resulting from a generic mitigation measure." It was not measured compared to NO MITIGATION whatsoever, which the summary insinuates.
MA Study: The plexiglass dividers were identified as one of three "possible risk factor" categories through "observation of smoke," not measurement. The other categories were "occasions of mask removal at distances less than 6', primarily for eating and drinking" and "high-traffic areas (especially in two-way entry/egress areas) and shared offices." Further, this was at ONE SCHOOL! "Because no additional cases were identified in screening among staff at other schools, or among middle school students, all other schools in the district continued hybrid or in-person learning." Of the three categories, I wouldn't put my money on the plexiglass dividers being the most likely contributing factor... but I'd also want to confirm with actual measurements across all of the categories, not just assumptions, guessing, and "observation of smoke."
GA Study: The summary already includes the qualifier "compared with ventilation improvements and masking," but doesn't include a comparison to NO MITIGATION. Looking at the study, classrooms with "desks or tables with barriers" for "all classrooms" had 2.92 cases per 500 students enrolled. That was better than the following mitigation characteristics that were also measured: Optional mask requirements for teachers and staff members (4.42), Optional mask requirements for students (3.81), Flexible medical leave policies for teachers not offered (3.98), No ventilation improvements (4.19), Unknown ventilation improvements (2.95), Desks or tables separated by greater than/equal to 6 ft in some/no classrooms (3.09), Desks or tables separated by greater than/equal to 6 ft in all classrooms (3.02), and desks or tables with barriers in some/no classrooms (3.13). Based on those numbers, it's pretty safe to assume that desks or tables with barriers for all classrooms also performed better than no mitigation whatsoever, especially when you look at the rates in Private/Parochial/Independent schools (4.05) and Nonmetropolitan schools (3.41) that likely had little/no mitigation.
Cubicle Study [1] [bolding by me]: The summary just plain got this WRONG! "The patient with the index case of TB was working as chief of staff in a large commercial business office [...] Screening was extended on two occasions to take in the whole ground floor, reception and mezzanine level, and to include staff who transited the area on a regular basis [...] The workplace had an open-plan design with low-profile cubicle dividers and closed air conditioning. The practice of 'hot-desking' (where most staff are not allocated a permanent desk) involved about 75%–80% of the staff in the main office area. The patient with the index case of TB had a permanent desk." In the discussion: "In our case, there were several factors in the workplace design that may have contributed to transmission including a closed air-conditioning system, modern open-plan office design with low profile design of cubicle dividers that allows workers to see and communicate directly with their colleagues without standing, and the practice of 'hot desking'." It was LOW dividers (essentially, NO DIVIDERS) that contributed to the spread, not HIGH dividers.
British Research: Meta analysis. They got the Lessler (Johns Hopkins) study wrong. Their take on the Johns Hopkins study completely ignores that it was a comparison to other mitigation, not a comparison to NO mitigation: "A
May make (Score:2)
speculation
It's airborne - and it's fresh air that's missing (Score:4, Insightful)
You can rearrange deck chairs and dividers all you like. But if your HVAC system keeps recirculating air, it won't do much good.
The solution to pollution (in this case) is dilution. Fresh air is what prevents viral load building up in ambient air.
Hunt down your HVAC person and force them to 'open the dampers'. Yes, it'll cost more, but not more than your life.
"Open outdoor air dampers beyond minimum settings to reduce or eliminate HVAC air recirculation." [cdc.gov]
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Here you big baby. It takes all of five seconds to open a new tab and paste the link. https://archive.is/o5zZK [archive.is]
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Worse, his is the generation the rest of us is depending upon to save us from Covid-19.
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