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

nature.com

41–50 of 176 posts

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

#41
post #28

> “This study suggests that HEPA air cleaners, which remain little-used in Canadian hospitals, What, they are "little used"? I'd assume that's the first place that would have adopted them. So strange how some hospitals operate.

I suppose the cost of installation outweighed the minor inconvenience of colds and flus spreading in the past. Only now that we have a deadlier virus does it make sense.

Most likely. Canada also has a habit of under-spending on healthcare in general. The system is also hypersensitive to political whims and can end up getting neglected as a result. This is because the provinces have direct control over every aspect of the healthcare system, and set the budget for them directly.

Unlike other nations like Germany and Estonia, Canada's healthcare system is fully dependent on the provincial government to exist and be funded. If I'm not mistaken, in the two countries I mentioned, clinics can get private funding while providing universal access in most cases, which means they have a larger buffer between the political whims of the state, and their ability to provide service. If the state under-provides, the clinics can seek investors to cover the new costs, all the while maintaining universal coverage.

That's not something Canadians can do. Talk of any private involvement, or restructuring in general, in Canada's healthcare system is often very politically charged and not particularly honest, so change is not happening any time soon.

I suspect the issue here is that the hospitals know that having HEPA filters would be a good idea, but political will isn't there to give them what they need. Canadian politics on both sides lately has been more about the appearance of progress through large gestures, rather than careful consideration of long term solutions. It's very unfortunate.

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

#42

Earlier quoted context omitted.

> 1x 20x20 MERV-13+ MPR-2400+ HVAC air filter ($20) That's a MERV-13 filter, not a HEPA filter. HEPA filters 99%+ of small (0.3um) particles per pass. A MERV-13 filter only filters like 60% per pass IIRC. That means that a 1000 cu. feet of air through the HEPA filter will result in 990+ cu. feet of clean air. While the MERV-13 filter will only produce 600 cu. feet of clean air. -------- A MERV13 filter would be good…

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/

Yeah, it's actually pretty complicated.

MERV13 also needs less pressure, and a box fan is bad with pressure. If you stuck a HEPA filter on a box fan, it might only do 100cu feet of airflow. MERV13 is maybe 200.

HEPA is designed for higher pressure centrifugal fans. MERV13 is likely the best balance for home made designs

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

#43
post #36
post #28

> “This study suggests that HEPA air cleaners, which remain little-used in Canadian hospitals, What, they are "little used"? I'd assume that's the first place that would have adopted them. So strange how some hospitals operate.

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…

Airborne transmission and the usefulness of filters still doesn't seem that clearly established - this study didn't find that much virus in the air even without the filters, and most of the real-world transmission seems to involve people who were directly exposed to virus particles before they even had a chance to go through a filter, via standing next to someone or directly in an airflow path coming from their direction.

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

#44

Earlier quoted context omitted.

I'm student teaching in a third grade classroom, and I want to add a least a small counter: We are required to have two HEPA filters always running in the classroom. They are loud. Combined with the fact that (1) children mumble, (2) the children have masks on, and (3) everyone is supposed to stay 3+ feet apart, it's quite hard to hear what a lot of kids are saying! I don't know what the right answer is, but what we…

The point would be to have the central HVAC system be renovated to boost circulation with HEPA filters in the loop precisely so that you don't have to have two noisy things doing a middling job of a similar task in the classroom itself.

> have the central HVAC system be renovated

Speaking for many schools in heating dominated climates: renovate the what? (Many schools have forced water radiators, which are obviously not able to be retrofitted for effective air filtration.)

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

#45
In Canada, Many school, and public buildings still have asbestos used throughout and very outdated ventilation systems. Schools in smaller towns were built in the 60s and 70s. Asbestos was a town in Quebec before they changed the name.

Vaccines are pushed in part so hard, because its the cheapest solution for government to implement. Not building extra hospitals. Firing unvaccinated nurses, and hospital employees during a pandemic is the other government solution. This of course will blow back hard, should the vaccine efficiency wane over winter.

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

#46

You can build your own high-flow HEPA filter for about $45: 1x 20-inch box fan ($20) 1x 20x20 MERV-13+ MPR-2400+ HVAC air filter ($20) 1x roll of duct tape ($2.50) Air particle meters and other testing show they work just as well as big expensive machines (it's just the filter doing all the work). This is indeed a dirt cheap way to improve overall health.

I see people post this all the time, but I really don't think an axial fan can pull air through a HEPA-like filter. You need to spend $150 on a real solution. It's really not much, includes the filters, and looks a hell of a lot better to boot.

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

#47

Earlier quoted context omitted.

I have believed this for about a year, based on things I was reading at that time. I thought this was widely known because as you point out, that’s kinda their purpose. This article acknowledges that it was shown to be effective in lab settings and this is mainly about seeing those results in real life settings. But come on, if anyone finds something that’s probably effective based on science and isn’t going to negat…

I'm student teaching in a third grade classroom, and I want to add a least a small counter: We are required to have two HEPA filters always running in the classroom. They are loud. Combined with the fact that (1) children mumble, (2) the children have masks on, and (3) everyone is supposed to stay 3+ feet apart, it's quite hard to hear what a lot of kids are saying! I don't know what the right answer is, but what we…

There's quiet filters. I can barely hear the one(s) in my house, and they're just cheapo ones. Typically the key is to keep the fan speed reasonable, if you crank it up all the way almost any fan is going to be loud.

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

#48
post #36
post #28

> “This study suggests that HEPA air cleaners, which remain little-used in Canadian hospitals, What, they are "little used"? I'd assume that's the first place that would have adopted them. So strange how some hospitals operate.

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…

> 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.

Wouldn't that just be because of protocol, ie. they don't know if you, a member of the public, actually have a legit N95 mask, or if you know how to correctly implement it, etc.

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

#49
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…

> 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. Wouldn't that just be because of protocol, ie. they don't know if you, a member of the public, actually have a legit N95 mask, or if you know how to correctly implement it, etc.

Is a surgical-mask better than a fake N95 mask?

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

#50

Earlier quoted context omitted.

The point would be to have the central HVAC system be renovated to boost circulation with HEPA filters in the loop precisely so that you don't have to have two noisy things doing a middling job of a similar task in the classroom itself.

> have the central HVAC system be renovated Speaking for many schools in heating dominated climates: renovate the what? (Many schools have forced water radiators, which are obviously not able to be retrofitted for effective air filtration.)

They probably have those with windows that open, too, thanks to the last pandemic.
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