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The experiment that proved airborne disease transmission

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Re: The experiment that proved airborne disease transmission

#71

Post by jchw »

hahajk wrote: post #45
jchw wrote: post #27

Earlier quoted context omitted.

While I understand the frustration, the reality is we shouldn’t be making fun of either. Just because the end result of something is inarguably “stupid” does not mean that any of the things that went into it are “stupid.” To do the Hacker News thing and make a bad analogy to computer science topics in a totally irrelevant thread, this is how I view a lot of stuff people complain about these days (think JavaScript, or…

Keeping information from the public to avoid mass hysteria is one thing, but keeping information from hospitals so they don’t have to implement prohibitive protocols is daft. If the healthcare response would be unreasonable, the right thing to do is to deliberately modify the protocols, not pretend the problem isn’t happening.

I'm not saying that the end result isn't stupid, just that sometimes no stupidity is actually required for us to end up in situations like this.

Re: The experiment that proved airborne disease transmission

#72

Post by jchw »

wbl wrote: post #38
jchw wrote: post #27

Earlier quoted context omitted.

While I understand the frustration, the reality is we shouldn’t be making fun of either. Just because the end result of something is inarguably “stupid” does not mean that any of the things that went into it are “stupid.” To do the Hacker News thing and make a bad analogy to computer science topics in a totally irrelevant thread, this is how I view a lot of stuff people complain about these days (think JavaScript, or…

The people who will die because we haven't told them how to protect themselves don't care.

OK. But not caring about how we get into no-win situations is exactly how we get into no-win situations.

Or perhaps in a different light, neither do the people who would've died if we had chosen a different branching path with negative consequences. There is some implication that there was a better outcome easily available and that is not clear at all. There should've been one, but there wasn't necessarily.

Re: The experiment that proved airborne disease transmission

#73

Post by saalweachter »

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 are allocating, say, 0.1 electrons, only 10% of your virus particles will have a charge.

Edit: so, given the capacitance of humans as 200 pF, that would be 5 gigavolts?

Re: The experiment that proved airborne disease transmission

#74

Post by dreamcompiler »

fyfy18 wrote: post #56
dangrossman wrote: post #33

Earlier quoted context omitted.

Any HVAC company can install this for you right now, or you can buy a kit and do it yourself. A UV light bulb to install in your central air system is an off the shelf product. "Whole house UV air purifier" as a search term will pull these up.

Are these products actually effective though? I mean the duration and intensity required to kill viruses in moving air must be quite high? Or is it just snake oil, like how a lot of hand dryers have bluish/purple LEDs (which emit no UV) that shine on your hands?

Yes, they're effective. But near-UVC is dangerous to your skin and eyes, so it absolutely must be shielded. Far-UVC is quite safe to humans, and just as effective against coronaviruses, but it's rather expensive at the moment.

https://www.researchsquare.com/article/rs-25728/v1

Re: The experiment that proved airborne disease transmission

#75

Post by [deleted] »

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…

[deleted]

Re: The experiment that proved airborne disease transmission

#76

Post by sudosysgen »

mantap wrote: post #68
nkurz wrote: post #63

Earlier quoted context omitted.

I think you are missing the OP's assumption that by raising the subject's entire body to +X Volts, any virus particles they breath out will start out with this same positive charge. I'm not sure this assumption is true, but it seems plausible.

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.

Re: The experiment that proved airborne disease transmission

#77

Post by curryst »

imposterr wrote: post #53
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?

Free electrons tend to distribute themselves on an object as to minimize the repulsive forces between them. This usually means that they distribute evenly on the surface of objects. Humans are a bit more complicated in structure than say a metal ball, but my guess would be that there would be a similar situation where all the free electrons would just build up on the skin. Therefore, I don't think the particles one w…

Alveoli are basically small air sacs in your lungs, so they're a surface (it's just an inverted ball, a hollow sphere in a not-so-solid object).

No idea how that influences where the electrons go.

I wonder how the nervous system would interact with that as synapses fire. I'm curious if they would build up, or if the synapses all over the body firing would make them bounce around constantly.

Re: The experiment that proved airborne disease transmission

#78

Post by 31337 »

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?

Germicidal irradiation via UV light on HVAC is just not possible. Due to the amount of energy it requires to be effective is ridiculously high.

https://www.climask.com.tr is interesting. Like a face mask on AC unit. Nano-silver is effective against bacterias and viruses. And having a filter with nano-silver coated surface is just a simple yet an effective approach. Cost-wise changing a good quality air filter every 2-3 months is much cheaper than having a UVGI installed and paying higher electricity bill every month.

Re: The experiment that proved airborne disease transmission

#80

Post by Gibbon1 »

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

I tried looking into that this spring. I suspect the answer is for this virus not much. Nothing to indicate that any part of it's life cycle involves hanging around latent.

Interesting bit on how UV-C works to sterilize.

https://en.wikipedia.org/wiki/Pyrimidine_dimer

Interesting thing bacteria and some viruses have DNA repair enzymes that can fix damage from UV-C. Medically you're always bedeviled by bacterial and fungal spoors.

Limitations with UV-C sterilization I think prevents wider use. Not a magic bullet. Though it probably works well for influenza, colds, and this bat virus.

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