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The experiment that proved airborne disease transmission

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Re: The experiment that proved airborne disease transmission

#81

Post by ISL »

nostromo wrote: post #13
lucb1e wrote: post #12

TL;DR: the actual experiment: > they constructed an air-tight closed ventilation system that connected a six-room tuberculosis ward to an exposure chamber with 150 guinea pigs. (Among rodent animal models, only guinea pigs could cough and sneeze, making them ideal for studying how respiratory diseases spread.) The guinea pigs were exposed to the infected air over a four-year period. A second group of 150 guinea pigs…

Today I learned: > The animals were used so frequently as model organisms in the 19th and 20th centuries that the epithet guinea pig came into use to describe a human test subject. https://en.wikipedia.org/wiki/Guinea_pig

In the same spirit, I offer Tami Knight's Avalanche Poodle: https://www.snowmediazone.com/the_zone/data/500/medium/Avi_p...

Among my friends, to go first in an uncertain situation is sometimes called, "poodling it".

Re: The experiment that proved airborne disease transmission

#82

Post by praptak »

sharpercoder wrote: post #7

Can ultra-high resolution, ultra-high framerate and ultra-high zoom camera's measure exhalation of virii particles out of a humans mouth?

Resolution of plain optics only goes up to the diffraction limit, which is not enough to see a virus.

Then there are super-resolution techniques which can go beyond that, but I don't think any of them could be adapted to scan the vicinity of the coughing human in real time.

Re: The experiment that proved airborne disease transmission

#83

Post by R0b0t1 »

computator wrote: post #55
ajb wrote: post #32

Ok, dumb idea time: suppose that everyone in an office sits on a chair that raises their body to X volts. At the same time a collector mesh is provided at each desk, at -X volts, but shielded so that you can't touch it and shock yourself. What X is large enough to ensure that all the virus particles you cough out end up at the collector? Is it possible to do this without electrocuting everyone?

This seems to assume that virus particles are charged. If they are neutral, they wouldn't be driven in any direction by an electric field. Am I missing something? Is it known that virus particles have a charge?

Particles in the air respond to charges. https://en.wikipedia.org/wiki/Electrostatic_precipitator

Re: The experiment that proved airborne disease transmission

#84

Post by R0b0t1 »

ajb wrote: post #32

Ok, dumb idea time: suppose that everyone in an office sits on a chair that raises their body to X volts. At the same time a collector mesh is provided at each desk, at -X volts, but shielded so that you can't touch it and shock yourself. What X is large enough to ensure that all the virus particles you cough out end up at the collector? Is it possible to do this without electrocuting everyone?

You don't need to raise the person's potential for this to work, though it could make it more effective. https://en.wikipedia.org/wiki/Electrostatic_precipitator

Places like hospitals filter the air internally to reduce infection.

Re: The experiment that proved airborne disease transmission

#85

Post by Adferdfqwer »

sudosysgen wrote: post #76
mantap wrote: post #68

Earlier quoted context omitted.

If you could really positively charge your whole body to +X volts wouldn't that interfere with your nervous system?

The electric potential is relative. It's potential differences that matter.

Eueu

Re: The experiment that proved airborne disease transmission

#86

Post by Apofis »

saalweachter wrote: post #73
ajb wrote: post #32

Ok, dumb idea time: suppose that everyone in an office sits on a chair that raises their body to X volts. At the same time a collector mesh is provided at each desk, at -X volts, but shielded so that you can't touch it and shock yourself. What X is large enough to ensure that all the virus particles you cough out end up at the collector? Is it possible to do this without electrocuting everyone?

The mass difference between humans and viruses is something like 10^19. So if you take the naive approach -- which is wrong, because charges live on surfaces, not in volumes -- you would want the person to have about a coulumb of charge to ensure that 1 extra electron was allocated to each virus particle. Whether or not 1 electron per virus is enough is a separate question, but that gives you a lower bound -- if you…

Somebody get Elon on the horn, we have the world to save!

Re: The experiment that proved airborne disease transmission

#87

Post by neilwilson »

contravariant wrote: post #16
lucb1e wrote: post #12

TL;DR: the actual experiment: > they constructed an air-tight closed ventilation system that connected a six-room tuberculosis ward to an exposure chamber with 150 guinea pigs. (Among rodent animal models, only guinea pigs could cough and sneeze, making them ideal for studying how respiratory diseases spread.) The guinea pigs were exposed to the infected air over a four-year period. A second group of 150 guinea pigs…

Some things worth pointing out about the linked article (not by Riley), regarding masks and disinfecting air: https://ajph.aphapublications.org/doi/10.2105/AJPH.2006.0962... - It contains no experimental data, it's a review of possible methods. - It's not about Covid-19, although that's to be expected. - The masks it talks about are N95 and N100 respirators (which it notes aren't in adequate supply). Some interesting…

The logic is short in other terms.

It requires you wear the mask at all times. And that you change it regularly by removing folding inwards and disposing securely.

Otherwise you may pick up an infection and then put a mask on afterwards which necessarily means that much of the shedding caught in the mask will be breathed back in - From mouth to nose and vice versa.

Or put the mask back on backwards or wave it around in the air, put it on surfaces and the like.

All of which amplify the current infection you have making you more infectious when you take the mask off.

And may explain why at a local Covid secure school they all went down with the usual back to school viral cold far more rapidly this year than they normally do.

What we don’t know - because we’re not hamsters permanently in cages - is what the network effects are.

Re: The experiment that proved airborne disease transmission

#88

Post by ajb »

saalweachter wrote: post #73
ajb wrote: post #32

Ok, dumb idea time: suppose that everyone in an office sits on a chair that raises their body to X volts. At the same time a collector mesh is provided at each desk, at -X volts, but shielded so that you can't touch it and shock yourself. What X is large enough to ensure that all the virus particles you cough out end up at the collector? Is it possible to do this without electrocuting everyone?

The mass difference between humans and viruses is something like 10^19. So if you take the naive approach -- which is wrong, because charges live on surfaces, not in volumes -- you would want the person to have about a coulumb of charge to ensure that 1 extra electron was allocated to each virus particle. Whether or not 1 electron per virus is enough is a separate question, but that gives you a lower bound -- if you…

Wow, okay - that explains why we're not doing this already!

I'm curious as to why this logic doesn't apply to the electrostatic precipitator. Or maybe it does and we just have too much capacitance?

https://en.m.wikipedia.org/wiki/Electrostatic_precipitator

ETA: the EP causes Corona discharge, which doesn't sound like it would be too pleasant if you were the electrode.

Re: The experiment that proved airborne disease transmission

#89

Post by dehrmann »

femto wrote: post #42
lifeisstillgood wrote: post #23

UV-C lights that irradiate an air duct is literally the most surprising (and in retrospect obvious) thing I learnt today. Is this something a household HVAC could be upgraded to. Do HNers in areas that have air con think it's a "yeah people will want that" idea?

If DIYing, choose your UV wavelength wisely. UVC (around 254nm wavelength) is germicidal and doesn't produce ozone (it actually dissociates ozone). "Vacuum UV" (in the range 185nm) converts oxygen in the air to ozone, which is highly toxic. [1] http://www.uvresources.com/blog/the-ultraviolet-germicidal-i...

Also the whole skin cancer thing.

Re: The experiment that proved airborne disease transmission

#90

Post by dehrmann »

ajsnigrutin wrote: post #28
lifeisstillgood wrote: post #23

UV-C lights that irradiate an air duct is literally the most surprising (and in retrospect obvious) thing I learnt today. Is this something a household HVAC could be upgraded to. Do HNers in areas that have air con think it's a "yeah people will want that" idea?

I always wondered just how much UV-C do you need to effectively kill the virus (power vs duct diameter and air speed).... because, instead of traditional masks, you could take a small fan, blow air into a pipe with a UV-C bulb inside, and pump the sterilized air to the human... basically something like this: https://www.youtube.com/watch?v=fzGrh2io9Ds&app=desktop

The real question is is there a safe wavelength and low enough power where you could swap out fluorescent tubes and effectively manage the virus.
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