My awesome dentist didn’t reopen until they upgraded their ventilation. Each room is sealed off and he tells me that by the time I walk to the door the air I was breathing has been evacuated. HEPA filtration.

I just can’t stop myself from going to my favourite lunch spot though. Mask off to eat. I keep my fingers crossed and hoping the huge volume of space keeps any viral count low. The vaccine passport system only ended March 2022 though, so there’s that.

The plexiglass barriers are ridiculous too since they impede airflow. Dirty air just lingers instead of mixing & dispersing. Same goes for staff who put a mask on as soon as you walk into the business like they didn’t just fill the room with virus loaded air.

Paul, I haven’t found the 96% statistic but it may have come from this article, which says:

“It can be shown that over 94% of COVID-19 superspreading events occurred in limited ventilation areas suggesting aerosolized transmission is a strong contributor to COVID-19 infections.”

Here’s the paper: https://www.medrxiv.org/content/10.1101/2020.10.03.20206110v6.full.

Your article will not persuade them, but it gives my co-habitants, who must toe the aerosol line or else (or else I have to move) some measure of comfort.

We are forgoing (and insulting) relatives who poo-poo our personal safety requirements…and in doing so prevent our close association.

Funny, now we are divided not only along race, wealth, and political lines, but split into aerosol vs droplets ‘scientists’….because our government has found it inconvenient to follow science.

Thanks for the work.

It sounds like the common wisdom says that up-drafting is the way to go, moving used air up to the ceiling and then removing and processing it. I wonder what air velocities are in the room. If doing a new install with this type system in mind, what would be the maximum spacing for makeup air registers in the floor? For collectors in the ceiling?

Tables would presumably be something of a dead space both because of obstruction but also because most people might get squirrelly about a strong draft blowing up their legs. With fully adequate central air volume (fans, ducts, registers, etc), would the flow around the tables be enough to carry upwards exhalations from customers or would there need to be some kind of fan at each table to move the air column above the table upwards? Like the little table filters in that example.

12 tables, four sensor locations if I read it right. That’s’ not too high a bar. Sounds like monitoring might be relatively easy.

This might impact wall-to-wall carpeting in public areas…

Cheers,
Rufus

Rufus, other people have been noodling over that problem, too. Here’s an article in the Washington Post showing how it can be done in a restaurant:

https://www.washingtonpost.com/health/interactive/2021/indoor-air-quality-safety-experiment/

They did it with portable air cleaners, but they paid careful attention to the air flow.

Say I’m a restaurant developer planning, oh, 12 tables in a room of, say, 400SF. Make it easy and allow full access below and 15-20′ ceiling height above. Registers, ducts, maybe a few <4' high dividers or some sort… Room penetrations (doors, windows) controlled anyway you like. Not limited to existing HVAC fixtures, but if you make up something new, it must be manufactureable with existing tech. Central system can be augmented with micro control by in-room fans. Monitoring needed and archived to document room's design performance and reduce legal liability from any customer illness… What monitoring would be helpful and possible? What room airflow plan is possible? "Active" system adjustments for different crowds. Minimize air flow velocity in room (no drafts…).

Maybe just one big down draft spread over the whole floor space, like a huge Jennair downdraft stove top. Or a room sized air hockey board in reverse? Or should the flow be up? Or individual table registers?

Or tweek the example. Say a hospital waiting room. ER. Whatever.

Ideas? All this technology piling up in the world, seems like this might be a worthy problem.

Regards,
Rufus

Paul, I’ll have to dig that up. I should have put in the reference when I wrote the article, but I’ll find it and come back with the source.

Allison
I wrote an article indicating aerosol was the main culprit, but this is the first time I’ve seen 96% or any percent.
If you have a link on that, it would be great to have it.