It's a minor point, but it's interesting that they used having AC as a proxy for mechanical ventilation and conclude that it's rare in Europe. At least where I live (NL), mechanical ventilation is common - I think required in some situations - even though AC isn't. It's basically a fancy extractor fan that pumps air outside, so bringing fresh air in. That said, you'd need to reverse that flow to add filters.
Germicidal UV could make airborne diseases as rare as those carried by water
31–40 of 70 posts
Re: Germicidal UV could make airborne diseases as rare as those carried by water
#32Idiotic and massively overlooks/underestimates how complex biology is. What about beneficial and neutral but important bacteria and viruses? "Air" is actually a complex soup of all types of things. This like applying HCl to a skin infection.
I doubt it would be a problem for the microbiome [1] but I would worry about the immune system. Would being inside in sterilized air all the time mean you can't go outside or into a forest without getting really sick?
[1] but who am I, it would still be worthwhile to check obviously
Re: Germicidal UV could make airborne diseases as rare as those carried by water
#33Wont micro-organisms quickly adapt and start producing UV resistant strains?
There is a giant orb in the sky that emits UV and has for billions of years. I think the microbes are still trying to figure this one out.
> I think the microbes are still trying to figure this one out.
They mostly figured it out a couple billion years ago. Cyanobacteria oxidized Earth's surface until the atmosphere was flooded with molecular oxigen, that gets turned to ozone in the stratosphere, filtering most UV. Pretty large engineering feat for a bunch of microbes.
Re: Germicidal UV could make airborne diseases as rare as those carried by water
#34It's a minor point, but it's interesting that they used having AC as a proxy for mechanical ventilation and conclude that it's rare in Europe. At least where I live (NL), mechanical ventilation is common - I think required in some situations - even though AC isn't. It's basically a fancy extractor fan that pumps air outside, so bringing fresh air in. That said, you'd need to reverse that flow to add filters.
Yes, few people have AC but almost everyone living in a semi recent place has mechanical ventilation in, at the very least, kitchen and bathroom, which thanks to physics renew the air of the entire falt/house.
Re: Germicidal UV could make airborne diseases as rare as those carried by water
#35Wont micro-organisms quickly adapt and start producing UV resistant strains?
I also wonder about stuff like this. I think some things are just a bridge-too-far for organisms to evolve protections against. For instance, are we worried about using too much bleach? Or stepping on cockroaches?
There are radiotrophic fungi that thrive in Chernobyl, so I wouldn't hold too much hope for UV either. It probably won't be able to penetrate a decent biofilm.
Re: Germicidal UV could make airborne diseases as rare as those carried by water
#36No mention of ozone. The more directly dangerous 254nm UV light has the advantage that it doesn't create ozone. Viruses and bacteria aren't the only bad things you don't want in your air. Ozone is thought to be a carcinogen in its own right and aggravate the health effects of particulate pollution. We want filtering and air circulation anyway, we don't want anything that makes it worse. The consumer electronics indus…
Could accumulate in an isolated room, but following normal building ventilation standards, really shouldn't be an issue as shown by Brenner in 2023: https://pubmed.ncbi.nlm.nih.gov/38037431/
article specificaly mentions rooms with poor ventilation. if you have proper ventilation, then you don't need this system in the first place, because you will get ouside air UV sterilised by the sun...
Re: Germicidal UV could make airborne diseases as rare as those carried by water
#37I have worked on such systems at Signify: There are numerous barriers to wider adoption except for very high risk situations. For instance: there have yet to be lawsuits to determine the risk of exposing people to UV. As you see in the comments below, any "UV" is considered dangerous by people not aware of the biological effects of various wavelenghts. Besides this, excimer lamps have a low expected lifetime, of both…
Every year our HVAC company tries to sell us UV lights for the HVAC system. They claim it's only about $1500 to install. Are these snake oil?
Depends on your HVAC system and the maintenance cost in your area. For me at 150€ per intervention it wouldn't make any sense, but I have heard some HVAC develop a smell and in that case, UV is likely to prevent it.
Re: Germicidal UV could make airborne diseases as rare as those carried by water
#38Idiotic and massively overlooks/underestimates how complex biology is. What about beneficial and neutral but important bacteria and viruses? "Air" is actually a complex soup of all types of things. This like applying HCl to a skin infection.
> What about beneficial and neutral but important bacteria and viruses? Such as what? There are some located in the gut, but pretty much everything else out there is in conflict with our immune system.
where are you getting this info?
almost every mucosal surface has commensal bacteria which can provide colonization resistance by other bacteria. lungs, skin, vagina, etc..
Re: Germicidal UV could make airborne diseases as rare as those carried by water
#39UV causes melanoma which is why we wear sunscreen.
too much UV all at once, you mean. melanoma is not common and face and arms - the regions which receive the most sunlight
a moderate amount of UV stimulates vitamin D production, suppresses inflammation, and turns on DNA repair pathways
Re: Germicidal UV could make airborne diseases as rare as those carried by water
#40Interesting, but I use a much more powerful germicidal UV source. Because of the power requirements it uses a fusion energy source located ~150M km away. (sunlight in fresh air.)
In fairness to the article, ventilation was mentioned, but also quickly dismissed. The 60% efficiency figure quoted for ERV is also a bit on the low side for many contexts. And sure, ERV fans themselves use some power (say 50W) but that's about what you'd use in a decent size room with some UV lamps and a fan.