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Real-world data show that filters clean Covid-causing virus from air

nature.com

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Re: Real-world data show that filters clean Covid-causing virus from air

#131

Post by loonster »

Pxtl wrote: post #105
nprz wrote: post #74

Someone made an interesting point that we got rid of cholera by drinking cleaner water and that we'll get rid of Covid by breathing cleaner air.

"air is the new poop" is what public health dr David Fisman says... Which is hyperbolic but succinct.

After you read about the Amoy Gardens and SARS1, you will no longer think of it as hyperbolic.

https://pubmed.ncbi.nlm.nih.gov/16696450/

>Abstract

>Recent investigations into the March 2003 outbreak of SARS in Hong Kong have concluded that environmental factors played an important role in the transmission of the disease. These studies have focused on a particular outbreak event, the rapid spread of SARS throughout Amoy Gardens, a large, private apartment complex. They have demonstrated that, unlike a typical viral outbreak that is spread through person-to-person contact, the SARS virus in this case was spread primarily through the air. High concentrations of viral aerosols in building plumbing were drawn into apartment bathrooms through floor drains. The initial exposures occurred in these bathrooms. The virus-laden air was then transported by prevailing winds to adjacent buildings at Amoy Gardens, where additional exposures occurred. This article reviews the results of the investigations and provides recommendations for maintenance and other measures that building owners can take to help prevent environmental transmission of SARS and other flulike viruses in their buildings.

Re: Real-world data show that filters clean Covid-causing virus from air

#132

Post by TylerE »

berberous wrote: post #58
overton wrote: post #36

Earlier quoted context omitted.

Early on in the pandemic, the Canadian IPAC (Infection Control and Prevention) establishment came down hard against theories of airborne COVID transmission, at first even going so far as to not recommend masking. Even now that the science of airborne transmission has been established, they're waging a rearguard battle to obfuscate/deny it and airborne protections such as better ventilation and masking. If you go to a…

N95s often have exhaust filters which make a surgical mask safer for everyone else around you.

It's quite easy to find ones that don't.

Re: Real-world data show that filters clean Covid-causing virus from air

#133

Post by dmix »

_3ddw wrote: post #130
jbay808 wrote: post #53

Earlier quoted context omitted.

> If you go to a Canadian hospital wearing an N95 these days there's a good chance they will insist you to take it off in favour of a "clean" surgical mask with gaps around the sides and nose. Happened to me many times. Sometimes they let me wear it over my (certified) N95, sometimes they don't.

I am so confused… how do they think covid spreads, then? Why should you wear a surgical at all, then?

The sign I saw at a hospital in Toronto said no fabric masks, only surgical. It’s probably about uniform coverage not overall efficiency, a compromise of most big central systems.

Re: Real-world data show that filters clean Covid-causing virus from air

#134

Post by [deleted] »

dmix wrote: post #133
_3ddw wrote: post #130

Earlier quoted context omitted.

I am so confused… how do they think covid spreads, then? Why should you wear a surgical at all, then?

The sign I saw at a hospital in Toronto said no fabric masks, only surgical. It’s probably about uniform coverage not overall efficiency, a compromise of most big central systems.

[deleted]

Re: Real-world data show that filters clean Covid-causing virus from air

#135

Post by jrochkind1 »

asdff wrote: post #122
notatoad wrote: post #112

Earlier quoted context omitted.

>You won't often catch covid from... how do you know? it seems like most cases are attributed to the nebulous "community spread" and nobody is really sure who they're coming from or how we're catching it. maybe we are getting it from the person breathing near us - if masks help, i don't see a reason that improved air filtration wouldn't.

All the data suggest that its not someone breathing on you in passing that's going to result in covid infection, but spending long periods with someone indoors in close proximity. Within a half hour in the massive grocery store? I would be shocked if you caught it. Drinking in someones living room, swapping stories within arms length, swapping spit flecks for 5 hours straight? Definitely going to spread everything yo…

> but spending long periods with someone indoors in close proximity.

It's not obvious to me that in-room air filters wouldn't reduce the exposure in this case, as the original commenter claimed? If it reduces the virus in the air, as the OP study finds, it seems like it probably would reduce virus exposure and thus infection rate when spending long periods indoors in close proximity, no?

Sure, just because it reduces the virus in the air doesn't necessarily mean it reduces infection -- like hypothetically the virus could commonny be going right from someone's exhale to someone else's inhale without having a chance to be filtered -- which I think is what the original commenter was suggesting -- but that's not the "spending long periods" scenario at all. I think it's true that while you probably can get infected in as little as ~15 minutes (not necessarily in just a couple minutes), but also clear that the longer you are in the same room, the higher risk.

But sure, we don't know exactly everything. All we can do is build knowledge one brick at a time, AND all we can do is act on the bricks we already have (that we don't have the whole wall yet is not a reason to avoid acting on our best picture (mixed metaphor, sue me) form what we do have)... but reducing virus in the air is a pretty huge brick for a respiratory infection. Based on everything we do know, it is hard to believe what the original commenter asks us to, to believe that reducing viral concentration in the air would NOT significantly lower infection rate.

I think it's becoming increasingly clear we should be spending at least as much attention on HEPA air filtration as people have been on masks.

Re: Real-world data show that filters clean Covid-causing virus from air

#136

Post by Pxtl »

loonster wrote: post #131
Pxtl wrote: post #105

Earlier quoted context omitted.

"air is the new poop" is what public health dr David Fisman says... Which is hyperbolic but succinct.

After you read about the Amoy Gardens and SARS1, you will no longer think of it as hyperbolic. https://pubmed.ncbi.nlm.nih.gov/16696450/ >Abstract >Recent investigations into the March 2003 outbreak of SARS in Hong Kong have concluded that environmental factors played an important role in the transmission of the disease. These studies have focused on a particular outbreak event, the rapid spread of SARS throughout Am…

I assume those floor drains lacked a functional p-trap because I've read with covid that disease would spread through drains without a proper p-trap, but otherwise the p-trap prevents drains like toilets and sinks from stinking and allowing contaminated air through.

P-traps can dry out though, but they stink if they do. Maybe that's what happened there?

Edit: yes, that's the theory - floor drains with dry u-bends allowed the poop air out.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC539564/

Re: Real-world data show that filters clean Covid-causing virus from air

#137

Post by taeric »

asdff wrote: post #122
notatoad wrote: post #112

Earlier quoted context omitted.

>You won't often catch covid from... how do you know? it seems like most cases are attributed to the nebulous "community spread" and nobody is really sure who they're coming from or how we're catching it. maybe we are getting it from the person breathing near us - if masks help, i don't see a reason that improved air filtration wouldn't.

All the data suggest that its not someone breathing on you in passing that's going to result in covid infection, but spending long periods with someone indoors in close proximity. Within a half hour in the massive grocery store? I would be shocked if you caught it. Drinking in someones living room, swapping stories within arms length, swapping spit flecks for 5 hours straight? Definitely going to spread everything yo…

What data are you referring to? The protests and marches last year seem to be hard to ignore example of things that should have had more spread by these standards.

Re: Real-world data show that filters clean Covid-causing virus from air

#138

Post by bmeski »

drzaiusapelord wrote: post #115
notatoad wrote: post #112

Earlier quoted context omitted.

>You won't often catch covid from... how do you know? it seems like most cases are attributed to the nebulous "community spread" and nobody is really sure who they're coming from or how we're catching it. maybe we are getting it from the person breathing near us - if masks help, i don't see a reason that improved air filtration wouldn't.

Because understanding how viruses spread is a solved art. None of this is "unknown."

In the same way that people are dumbfounded that natural immunity from having it is superior than the vaccine.

It’s as if we all forgot how viruses work.

Re: Real-world data show that filters clean Covid-causing virus from air

#139

Post by cma »

diebeforei485 wrote: post #70
bsilvereagle wrote: post #23

Earlier quoted context omitted.

It’s worth noting that filter efficiency is a function of particulate size. A MERV13 and a HEPA filter are nearly equivalent for filtering pollen, but have drastically different performance for smoke and virus particles. There’s a plot 1/3 of the way down the page that shows the curves: https://frdmtoplay.com/nagivating-air-purification/

"Virus particles" do not float free in the air to spread disease. It's usually mostly salt water aerosols with a few virus particles in them.

The smaller a droplet is, the quicker it evaporates due to increasing surface area ratio.

Re: Real-world data show that filters clean Covid-causing virus from air

#140

Post by clairity »

auslegung wrote: post #124
clairity wrote: post #91

Earlier quoted context omitted.

using air purifiers like that for corona is mostly theater anyway, since air purifiers don't filter the air evenly (despite the misnomer metric "air changes per hour") in a room. mostly, it filters really well near the purifiers and poorly everywhere else. this of course depends on the strength of the fan, but for most consumer air purifiers, it's likely a few feet radius at best. that's not to say that even that isn…

So much of what you’ve said is wrong. Not saying you’re a terrible human being, but what we know about these things is still, unfortunately, not settled. Can you give citations for 1. Air purifiers don’t filter the air evenly (commercial ones since that’s the context). 2. Social distancing indoors is doing most of the work (ie is almost all that’s needed to stop the spread). 3. The virus isn’t free-floating live in t…

no, but you’re welcome to present your own perspective and rationale for discussion. research is ongoing, but we certainly have enough time and information to form and debate hypotheses by now.

for instance, this study did not link air filtration to a reduction in transmission, only that a hepa+uv filter can reduce sars-cov-2 from known aerosolized air, basically an expected result in a controlled study (not “real-world”, as claimed).

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