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UV Devices Could Keep Indoor Air Free of Viruses

nature.com

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Re: UV Devices Could Keep Indoor Air Free of Viruses

#61

Post by Khelavaster »

raverbashing wrote: post #29
clumsysmurf wrote: post #16

Earlier quoted context omitted.

Interesting, does this also apply to far-UVC (222nm)? Its not surprising that UV would be a catalyst in some undesirable scenario. I'm thinking about toxic residues left by cigarette smoking reacting with household surfaces. Research suggests that rooms facing the sun (with blinds open) have less bacteria and viruses because it is a disinfectant. I would have to imagine in many homes, UV is somewhat pervasive anyhow.…

Yeah While glass blocks some of UV light I'm not sure it would be a big problem. Especially if it's constrained to a tube, for example Couple it with an activated carbon filter and it should be good (also a HEPA filter of course)

Doesn't bacteria break down in activated carbon and release VOOCs?

Re: UV Devices Could Keep Indoor Air Free of Viruses

#62

Post by oifjsidjf »

> But the reasoning makes sense: down in that range, the penetration of such light is only a few microns, and it doesn't even get past the dead cells on the surface of the skin and the cornea of the eye!

Ah yes, scientists saying "trust us, it won't harm the body" for the 1000th time, and then after a decade and two they will be proven wrong again.

They never learn...

Re: UV Devices Could Keep Indoor Air Free of Viruses

#63

Post by crazygringo »

ciconia wrote: post #39

I find the obsession with having a sterile environment ridiculous. Our bodies themselves are teeming with microbes and viruses, actually our bodies contain more of them than our own human cells. They play an important role in our digestive system, as well as our metabolism and also keeping our immune system on its guard. What needs to be done is not to eliminate those actors, but rather to make our bodies resilient t…

Well now I'm curious. Do you feel the same way about malaria, which kills half a million people a year?

That we shouldn't attempt to remove malaria from our home environment with things like mosquito nets, but rather "make our bodies resilient"?

And... how exactly are we supposed to be making our bodies "resilient" against COVID and the flu and malaria? Seems like you've left out that crucially important detail.

To be clear, the microbiome in our gut has nothing to do with continued exposure to lethal airborne viruses. Sterilizing against one thing doesn't sterilize against everything.

Re: UV Devices Could Keep Indoor Air Free of Viruses

#64

Post by crazygringo »

cfn wrote: post #26
Auracle wrote: post #20

Earlier quoted context omitted.

That’s not an option for most climates.

Yes it is. I used to ventillate my room in Uni when it was way past -20 C outside. As long as you have decent heating it is not a big deal if you do it periodically.

"Not a big deal"...?

My electric bill would go up 4x if I was periodically ventilating my whole living space in the winter. Good lord. Are you going to pay that for me?

I mean, I understand that at Uni, you probably weren't the one paying your heating bill, so you didn't have any responsibility for your actions.

But in the real world, that's incredibly expensive, wasteful, and terrible for the environment (depending on your source of power).

So, yes, it kind of is a "big deal". Even if you didn't realize it at Uni because you were burning through someone else's money.

Re: UV Devices Could Keep Indoor Air Free of Viruses

#65

Post by mensetmanusman »

jansan wrote: post #58
a1371 wrote: post #4

When you talk to Indoor Air Quality (IAQ) most are uncomfortable with UV. Reason being that while you can get rid of viruses, you can also create volatile compounds. Our homes' air is like a soup of natural and synthetic chemicals. From your flooring wear to your decor off-gassing to cooking, there are elements in your air that may be safe as they are, but they can completely change when they hit something volatile l…

I have a cheap UV-C lamp that I purchased from ebay. Aside from the danger to your skin and eyes, after running for a few minutes there will be a distinct ozone smell in the room. Once I keept it on for a few hours in a small room (windows and door closed, no people inside). The ozone smell was still there after one week. So at least the lamp that I own would not be suitable for killing virii in indoor environments,…

If a cheap UV lamp doesn’t have a sub 200 nm absorber layer, it will generate orders of magnitude more ozone than it should:

https://www.uvccleaningsystems.com/cm/dpl/downloads/content/...

Be wary of cheap electronics. E.g. People have been blinded by green laser pointers that convert 1064 nm IR light because of removed ir blocking filters that certain low cost manufacturers remove out of ignorance.

Re: UV Devices Could Keep Indoor Air Free of Viruses

#66

Post by ciconia »

parkingrift wrote: post #57
ciconia wrote: post #39

I find the obsession with having a sterile environment ridiculous. Our bodies themselves are teeming with microbes and viruses, actually our bodies contain more of them than our own human cells. They play an important role in our digestive system, as well as our metabolism and also keeping our immune system on its guard. What needs to be done is not to eliminate those actors, but rather to make our bodies resilient t…

> What needs to be done is not to eliminate those actors, but rather to make our bodies resilient to potentiel pathogens. If we expose ourselves to these pathogens and wait a few thousand years we might naturally evolve to be resilient. …otherwise I have no idea what you’re proposing here. You can’t just decide to be resilient. Pathogens kill people. They don’t die because they lacked willpower.

How to make ourselves more resilient to disease:

- Less air pollution. - Less water pollution. - Pesticide-free food. - Less sugar consumption. - Physically active lifestyle. - Less stressful life.

Re: UV Devices Could Keep Indoor Air Free of Viruses

#67

Post by knodi123 »

pifm_guy wrote: post #41

Purifying air seems like a tricky challenge. How much energy would it take to fractionally distill air? Ie. Liquify all the air in your house, boil off just the gasses you want, and pipe that back? Then you could choose for example to have 23% oxygen instead of 20% for a little more alertness, 0 ppm CO2 for a fresh feeling, and get rid of all the trace offgasses, even those that wouldn't be absorbed by activated char…

We did that for my house for a while. It wasn't too expensive, just a couple million a month (after initial one-time costs like buying equipment and building the physical plant on a couple of neighboring acres). But in the end, factoring in plant maintenance and all the employees that it required, my family decided it would be more cost effective to just have weekly shipments of bottled gasses from a scientific supplier.

Re: UV Devices Could Keep Indoor Air Free of Viruses

#68

Post by Animats »

epicureanideal wrote: post #21
joe_the_user wrote: post #18

Earlier quoted context omitted.

All that makes sense - for an ordinary product in an ordinary market. But this seems like something that could make a serious dent in the covid situation and so government mandates and money could flow and get these much more widely deployed with strong standards.

Also possibly useful military applications. Heck, have the soldiers wear some goggles that have UV protection and just saturate the room in virus killing UV periodically if there’s a suspected biological attack. Although, why not just put this UV emitter in a big box that has some kind of light filter on it to keep the UV inside rather than worrying about top of the room and so on?

Because you have to push the air through the box with fans. If you can make the ceiling area a kill zone for viruses, ordinary convection effects will push all the air through it regularly.

Re: UV Devices Could Keep Indoor Air Free of Viruses

#69

Post by agumonkey »

slimsag wrote: post #15
wesapien wrote: post #9

Earlier quoted context omitted.

My uncle has ozone generators in his home. One of them is industrial strength and he only runs it when he is leaving his house for awhile. Does ozone produce by products? I vaguely recall hospitals used ozone to clean n95 masks.

Ozone is very dangerous. The EPA concluded it poses serious health risks back in 2013 (causes asthma and respiratory harm, short and long term exposure is linked to likely early death, and even linked to cardiovascular problems.) Cleaning air is simple; you don't need to look to obscure Ozone/UV devices. For gasses/VOCs, you need a carbon filter. The larger the filter and more air that moves past it, the better. You…

Do you know about carbon filter recycling ? if you pyrolyze the filter would it evaporate the toxic compounds and leave pure carbon lumps ready to reuse ?

Re: UV Devices Could Keep Indoor Air Free of Viruses

#70

Post by ac29 »

crazygringo wrote: post #64
cfn wrote: post #26

Earlier quoted context omitted.

Yes it is. I used to ventillate my room in Uni when it was way past -20 C outside. As long as you have decent heating it is not a big deal if you do it periodically.

"Not a big deal"...? My electric bill would go up 4x if I was periodically ventilating my whole living space in the winter. Good lord. Are you going to pay that for me? I mean, I understand that at Uni, you probably weren't the one paying your heating bill, so you didn't have any responsibility for your actions. But in the real world, that's incredibly expensive, wasteful, and terrible for the environment (depending…

Anecdotal, but: I have found opening windows to be very effective at reducing C02 (as measured with a good sensor) and not very effective at changing the temperature even when it is significantly colder outside than inside. I live in a single family detached house, so I'm not just getting someone elses heat through the walls.

My suspicion is that this has to do with the thermal mass of air versus the thermal mass of the rest of the house - bringing in ~10,000 cubic feet of fresh air with a fan doesnt take long and dramatically improves indoor air quality but doesnt change the temperature much.

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