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Comment by Perz1val | Hacker News Reader

Oh yeah, why don't we put an air purifier, UV lamp box combo in each office/classroom? I've never thought about that, but it seems like such an obvious thing to do now

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> Studies have shown that various immunological and autoimmune diseases are much less common in the developing world than the industrialized world and that immigrants to the industrialized world from the developing world increasingly develop immunological disorders in relation to the length of time since arrival in the industrialized world.[23] This is true for asthma and other chronic inflammatory disorders.[18] The increase in allergy rates is primarily attributed to diet and reduced microbiome diversity, although the mechanistic reasons are unclear.

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

That certainly seems reasonable -- that the immune system needs practice or otherwise it will start using its ammo on other "hey that's me!" stuff and cause auto-immune diseases.

But I also have to wonder if the kids with auto-immune diseases or "common" allergies elsewhere might just die the first time they encounter some event that'd otherwise be caught and treated in "the first world" ?

From the same wikipedia page:

> The hygiene hypothesis has difficulty explaining why allergic diseases also occur in less affluent regions. Additionally, exposure to some microbial species actually increases future susceptibility to disease instead, as in the case of infection with rhinovirus (the main source of the common cold) which increases the risk of asthma

I think having a common cold infection each year does not bring any benefits, it certainly does not make anybody immune to common cold

I remember having a lot of colds as a kid but haven't had one for years now. I may have gained immunity to a good number of the 200+ different types.

I would be surprised if there is no dire second order consequences to raising kids 8h per days in a sterile environment (or more if you also adopt this setup at home). The immune system needs to be used in order to work properly. Unless we want a life where we cannot step outside of the range of our UV lamps.

Maybe fewer consequences than you'd think...

https://rachel.fast.ai/posts/2024-08-13-crowds-vs-friends/

"Your Immune System is Not a Muscle"

> Four main categories of pathogens that humans deal with are viruses, bacteria, fungi, and parasites. The evidence for pathogens that may be beneficial to the immune system is almost entirely for parasitic worms and friendly (commensal) bacteria. In contrast, many viruses can even trigger the onset of autoimmune diseases or allergies.

The air outside is constantly sterilized by UV light.

Care to taste a spoonful of dirt in a sunny day to see how sterile it is?

I've done it, and aside from not being able to breathe well for a while while you douse your mouth and throat with a garden hose, nothing bad will come of it.

This is a pretty common thing kids do. They're generally fine.

As a kid that ocassionally ate dirt, you're usually fine after it, if you ignore the worms you'll poop afterwards. My point was that it's not sterile even if it's under the sun all day, as UV rays don't penetrate deep, and dirt is a good thermal insulator. Bacteria and parasites, specially their spores/eggs, can be very hardy. It's amazing what our digestive system is capable of handling.

> My point was that it's not sterile even if it's under the sun all day, as UV rays don't penetrate deep…

Then why make the point at all as a response to "The air outside is constantly sterilized by UV light"?

Because if sunlight really sterilized the air, which is transparent, it surely would disinfect every surface it touches. In reality, sunlight does disinfect, but life has evolved to withstand it enough to find a safe environment.

BTW, hospital UV sterilizers work better because they're more intense than sunlight's UV.

It certainly isn't sterile but if a spoonfull of dirt makes you sick then you should already be considered immune compromised.

Absolutely not, most UV is blocked by the ozone layer, this is why we don't all develop skin cancer at 15. Otherwise, what would be the point of the UV-sterilization method?

I'm one of those that tries to jokingly correct the proponents of an often touted phrase by retorting "If it doesn't kill you, it makes you stranger".

The anecdotic evidence they present of immune-system-is-not-a-muscle contradicts anecdotal evidence of doctors, nurses, kids who grew up in a dump, etc. never getting sick due to having amazing immune system.

I mean, we evolved in these conditions - plenty of UV rays, fresh/clean pre-industrial air, and quite a bit of built-in social distancing between ape tribes.

Putting people in a small poorly-ventilated box with a bunch of strangers (some of whom perhaps recently flew to the other side of the planet and back) is the abberant behavior, really.

We do. They are called windows. A simple open window lets in fresh air and piles of free UV light.

UVC is blocked by the ozone layer.

Plus the air is not always “fresh” depending on where you live and what time of year. Ozone, smog, smoke, etc.

Plus for those of us with allergies, an open window during for example ragweed season can be a nightmare.

And lots of other UV gets though. Sunlight remains a great disinfectant, maybe not as much as a narrow-spectrum bulb, but it still carries plenty of microbe-killing power. From the actual article:

>> In a paper submitted to the Royal Society of London, they described how over the course of six months they had used sunlight to prevent bacteria from growing in a tube.

Humans have known about this for millennia, with ancient doctors regularly telling people to expose wounds to sunlight. Even animals have been seen instinctively "sunning" a wound. (I remember a BBC doc about Antarctica where a penguin was shown exposing a bite wound to the low-angle sunlight.) Only in recent years has a fear of cancer caused us to retreat from any and all sunlight, a fear revisited as we learn the downsides.

https://pmc.ncbi.nlm.nih.gov/articles/PMC2290997

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