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

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

but at least in my region, the majority of cases still don't have a known source. maybe that's because people are catching it in scenarios where they're in close proximity to somebody for extended periods of time but forget about it when the contact tracers call them, and all cases are spread that way.

or maybe it's spreading in grocery stores and other casual contact scenarios but that's just impossible to measure or count. we keep hearing that there's no evidence of it spreading in schools, and yet as long as students are in school it spreads a lot more among students. is it not spreading there, or is it just really difficult to find the evidence of that?

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.

The important takeaway is SARS 1 had significant fecal-oral transmission and not just respiratory.

And yet I'm supposed to believe that SARS 2 is respiratory only despite the fact that the government has detected SARS 2 in sewer systems, one of the early Covid symptoms is diarrhea, and SARS 1 had significant number of infections by fecal matter.

Hopefully this will help.

Personally, I’d caution not to over-generalize this fact.

(central) air filtration can be effective against harmful pollutants, but not really against infectious agents like corona.

Yes, I am a Canadian. I lived there for 25 years. I have Canadian citizenship. Most of my family still lives there. I also ended up stuck in Ontario for most of COVID. I have family in Ontario, in Quebec, and elsewhere in the country. I don't think Ontario had a very good handle on COVID. It's also no secret that Canada is suffering a major staffing, and funding shortage in the healthcare sector right now.

While most of your reply is about dentists (I'll get to that later), I see you're comparing Canada's healthcare system to the USA. I'm not. Compared to other systems in NA, yes, it's much better since it's free and somewhat fair. But that's the problem. Canadians should be looking to other developed nations with public healthcare. Not to the United States which operates on a completely different paradigm. My comment that you're replying to is entirely contrasting Canadian healthcare with EU systems, not Americans.

> dental office reopened

The majority of dentists are private entities, and are not subject to the same funding rules as hospitals. They're not licensed through the same entities, funded, or managed in the same way at all. Likely why they were able to adapt so quickly. See: https://www.cda-adc.ca/stateoforalhealth/servicescanada/

> [..] they checked vaccination status and accepted the mask she walked in with.

I'm not really sure what you're getting at here, this does not really relate to funding, or anything I'm talking about really. This is more about safety policy, not funding, which is what I'm trying to discuss.

Don't get me wrong, I've had some good experiences with the system as well, but that does not mean it shouldn't significantly improved.

Maybe they coughed over shared food/drink trays.

That depends completely on where you live, there are plenty of places that still have indoor or outdoor mask mandates, despite them being completely useless.

That's why it's farcical. In my area, you're required to wear your mask when you enter a restaurant and keep it on until you reach your table. Employees spend 8 hours breathing in the building through a cloth mask. Many places are still serving using single-use dishware to "stop the spread". Many people are still walking around with gloves on.

I'm not saying these were bad recommendations at the time, but they've turned into talismans and rituals we do to ward off the evil spirit of COVID while people broadly go about their lives as before.

Meanwhile, things like updating and repairing HVAC systems or restructuring buildings to maximize airflow, which both actually address COVID and have actual positive effects on health and wellbeing get short shrift, because we're wearing masks, so we're safe, and doing real work is expensive.

Now this pandemic started around 2020, which is more than decade later.

So recommending cloth masks was and is indeed farcical. Doing it after recommending against mask usage is idiocy. And no, the world’s collective scientific understanding of masks didn’t change between 2020 and 2021.

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.)

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 the classroom

There's only 4 coronaviruses that causes a cold: HCoV-OC43, HCoV-HKU1, HCoV-229E, and HCoV-NL63

The rest are rhinoviruses.

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That's literally only 7 coronaviruses to care about (including the 4 that cause "common cold").