[HN Gopher] Study: Air purifier use at daycare centres cut kids'...
       ___________________________________________________________________
        
       Study: Air purifier use at daycare centres cut kids' sick days by a
       third (2023)
        
       Author : mji
       Score  : 326 points
       Date   : 2024-08-25 15:15 UTC (7 hours ago)
        
 (HTM) web link (yle.fi)
 (TXT) w3m dump (yle.fi)
        
       | unglaublich wrote:
       | Yes, please. My colleagues, who are parents, are constantly sick
       | whenever their children are at daycare, and I have no interest in
       | the constant coughing and/or getting sick myself.
        
         | BenoitP wrote:
         | On child #2, can confirm. We actually planned for it. By
         | planning for no activities. Just bunkering and resting for 2
         | months straight.
         | 
         | We began partial daycare on Thursdays + Fridays in winter.
         | Daycare is like Cancun for bacteria. Dry cold can weaken the
         | skin, and cold is good for bacterial protein stability.
         | 
         | The cycle begins: kid starts incubating on Thursday. On
         | Saturday he's sick, and you hope for a good lottery. Diarrhea?
         | Puking? Maybe not. But a runny nose most probably. These may
         | ruin your nights, still.
         | 
         | Sunday they are sick, and you begin to feel unwell. Monday the
         | kids is recovering, but you're still in it. By Wednesday you
         | should be good though. And then it's Thursday again.
         | 
         | On another topic air filtering is great for the kids I'm sure;
         | but I can't help wonder if it's just kicking the can down the
         | road.
        
         | wredue wrote:
         | There's some studies showing parents of kids in daycare are
         | sick upwards of 90% of the time.
         | 
         | I don't know if it was that much, but when my kids were in
         | daycare, it was definitely A LOT for sure. Work doesn't provide
         | nearly enough sick time for that period of being a parent. So
         | what are parents to do if they're not able to work from home?
        
           | tuna74 wrote:
           | I totally felt that!
           | 
           | My kids almost never got sick in daycare (1-2 days per year),
           | but especially the first year I felt like I had a cold most
           | of the time. But it improved later years.
        
       | switch007 wrote:
       | Good news. Hopefully a country as wealthy as Finland can just
       | roll this out countrywide without much thought, if not already
       | standard
        
         | readthenotes1 wrote:
         | Without much thought? Without much thought I would say that the
         | recent experience of preventing children from catching
         | communicable diseases have shown it to be a devil's bargain and
         | we would be wise to keep their immune systems constantly
         | exercised
        
           | switch007 wrote:
           | Without much thought regarding cost. Calm down lol
        
           | unsupp0rted wrote:
           | What evidence is there that it's possible to "exercise" an
           | immune system?
        
           | hirsin wrote:
           | What recent experience? Do you mean keeping them home from
           | school for covid? I don't think the knock on effects from
           | that are remotely traceable to their immune systems.
        
           | error_logic wrote:
           | As mentioned elsewhere in the thread, one can be exposed (and
           | have an immune response) to a viral load below what's
           | normally considered symptomatic. Then the immune system
           | learns, but doesn't have to go into over-drive which taxes
           | the rest of the body more destructively.
           | 
           | In other words: Filtering part of it from the air can make
           | exposure more like vaccination than full blown infection,
           | which is great.
        
           | terminatornet wrote:
           | Getting sick to stay healthy. Makes sense to me. Now will you
           | be exposing yourself to zika virus or HIV? Seems like those
           | would exercise your immune system quite a bit.
        
       | swagasaurus-rex wrote:
       | There was a great deal of interest in how to remove airborne
       | viruses during Covid.
       | 
       | One of the biggest takeaways seemed to be that UV light destroys
       | viruses in seconds.
       | 
       | Seems like there a lot of things we could do
        
         | plasticchris wrote:
         | Yeah, even a single UV bulb in the cold air return might be
         | effective. This is well known in hiking circles where UV is
         | used to sanitize water.
         | 
         | I might hook one up now that I have the idea.
        
           | morkalork wrote:
           | You can use UV to sanitize water to drink? Must be better
           | tasting than those gross iodine tablets!
        
             | amluto wrote:
             | You can! It works best if the water isn't cloudy.
             | 
             | You can also get chlorine dioxide tablet systems that are
             | less nasty tasting.
        
             | mauvehaus wrote:
             | You can, but it does not leave any residual ability for the
             | water to neutralize pathogens once you're done treating the
             | water.
             | 
             | If you dip a Nalgene bottle to fill it, then purify the
             | contents, you would typically then bleed the threads by
             | holding the bottle upside down and loosening the cap.
             | 
             | With chemical treatment, the iodine in the water works to
             | neutralize any pathogens that aren't flushed out of the
             | threads. If you've used UV, you're kind of hoping that the
             | flushing action has physically washed out anything
             | lingering in the threads.
             | 
             | Anecdotally, people using UV get more cases of waterborne
             | illness, but I don't know if anyone has rigorously studied
             | this. Hikers are naturally resistant to controlled
             | experiments.
             | 
             | If you don't like the flavor of iodine tablets, I recommend
             | AquaMira instead.
             | 
             | Source: AT ME-MA 2003, GA-ME 2010. UV was pretty popular by
             | 2010 and for a couple years after. Not planning a thru hike
             | at the moment, but I believe the Sawyer squeeze filter is
             | super popular now.
        
             | mdp2021 wrote:
             | It is a standard method for disinfecting water in
             | aqueducts.
             | 
             | https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradi
             | a...
             | 
             | > _UVGI for water treatment // Using UV light for
             | disinfection of drinking water dates back to 1910 in
             | Marseille, France. The prototype plant was shut down after
             | a short time due to poor reliability. In 1955, UV water
             | treatment systems were applied in Austria and Switzerland;
             | by 1985 about 1,500 plants were employed in Europe. In 1998
             | it was discovered that protozoa such as cryptosporidium and
             | giardia were more vulnerable to UV light than previously
             | thought; this opened the way to wide-scale use of UV water
             | treatment in North America. By 2001, over 6,000 UV water
             | treatment plants were operating in Europe_
             | 
             | And yes, there are also commercial products for home use.
        
           | amluto wrote:
           | If you have an appropriately sized filter holder, I would
           | just install a MERV 13 or 16 filter. They're very cost
           | effective, widely available, and they will remove non-living
           | crud, too.
           | 
           | The main problem is that many central air systems use crappy
           | _thin_ filter holders. A good low-resistance filter needs a
           | lot of area, and a 4" or 5" thick format works well, 2" is
           | marginal, and 1" sucks. A good filter holder costs under
           | $200, takes very little effort to install in a new system,
           | and is an incredible pain to retrofit into an existing
           | system. And good filters are essentially unsupported in
           | ductless systems.
        
           | elric wrote:
           | Hmm, I wonder how effective that would be. My small home's
           | ventilation system is currently taking in about 100m3 of
           | fresh air per hour. That's about 1600L/minute. Let's assume
           | the intake duct is about 20cm in diameter, and assume we can
           | place a bulb to illuminate a 50cm stretch of pipe. That's a
           | volume of about 16 liters. So the air would be in visible
           | range of the bulb for about half a second. Would that be
           | enough for a UV bulb to do anything?
           | 
           | This was back of napkin maths, could be way off.
           | 
           | Edit: sanitizing incoming air is probably pretty useless, as
           | the outdoor concentration of pathogens is likely very low to
           | begin with.
        
             | thelastparadise wrote:
             | Low in pathogens, maybe, but high in pollutants such as
             | diesel particulates, second hand cannabis, wildfire
             | emissions, etc.
        
           | schiffern wrote:
           | I looked into implementing this once. Some surprising things
           | I learned:
           | 
           | 1. You need UV-C (typically 222 nm), not just any old UV bulb
           | off Alibaba/Wish/Amazon.
           | 
           | 2. You need an extremely high UV light intensity to kill
           | viruses if the air is just flowing past the bulb (vs shining
           | UV on a coil to prevent bacterial/fungal growth, which is the
           | typical usage), and you need more intensity the faster the
           | air is flowing. Usually this requires multiple bulbs.
           | 
           | 3. You need to replace your UV-C bulbs every 1,000 hours or
           | so, because they rapidly lose intensity with operating time.
           | 
           | Just putting a "black light poster" bulb in your ducts won't
           | accomplish anything, other than perhaps giving you a false
           | sense of security.
        
             | bri3d wrote:
             | > You need to replace your UV-C bulbs every 1,000 hours or
             | so
             | 
             | I don't think this should need to be the case. Low pressure
             | mercury arc lamps (253.7nm) last 10,000 hours in water
             | treatment applications - a much more palatable replacement
             | timeline (1 year) vs every few weeks!
             | 
             | The short-lifetime bulbs are usually 222nm Far-UVC bulbs,
             | which are safe for human exposure. These shouldn't be
             | necessary to treat air as part of an enclosed HVAC system.
             | I feel that the hype around 222nm / "safe" UVC has done a
             | disservice to just using "dirty" 253nm UVC, which kills
             | everything just as well as long as you keep people from
             | being able to look at it.
        
               | schiffern wrote:
               | Thanks for the correction. It's been a while since I
               | looked into it!
               | 
               | Even replacing bulbs every 1 year seems like a lot more
               | than people are bargaining for. Most people seem to
               | expect UV will be a "Set It And Forget It" solution
               | (hence why they prefer it over filters), so they risk
               | neglecting the necessary replacement interval.
        
         | viraptor wrote:
         | I found it interesting that I haven't really seen the UV
         | sterilisation to be popular at healthcare points at large.
         | Where I grew up, the local surgery had the UV on in the whole
         | building after hours, and that was in early 90s EE. None of the
         | places I've seen since then used it (as far as I'm aware),
         | across many countries.
        
       | taeric wrote:
       | So from 10-13 down to 7-9? Nice.
       | 
       | Will be neat to see if the kids were still carriers, but managed
       | to keep the viral loads down such that they weren't "sick" during
       | that time. I recall a study a few years back that said kids at
       | that age were basically always sick, just not often symptomatic.
        
       | funnym0nk3y wrote:
       | However I think it is important for children to get sick. Humans
       | need pathogens to train their immune system.
        
         | AwaAwa wrote:
         | While I personally agree with this sentiment, the last few
         | years have made it amply clear that the population prefers
         | padded rooms to icky playground sandlots.
        
           | error_logic wrote:
           | Nuance: They're still getting exposed and thus gaining
           | immunity with the environmental filtering, just not so much
           | viral load as to be out of school [as often].
           | 
           | It's a win-win from that perspective and dismissing that
           | serves no one in the end.
        
             | Sakos wrote:
             | This tiny but significant factor is also why masks, even
             | surgical masks, are so helpful. They don't need to prevent
             | 100% transmission, just reduce the viral load received or
             | passed on.
        
         | WithinReason wrote:
         | How often and how sick? The more the better?
        
           | appplication wrote:
           | It's a good question. Obviously infinite sick is not
           | desirable. If it were possible to induce antibodies via e.g.
           | broad spectrum vaccinations would we see less sick kids in
           | total?
           | 
           | After all the merits are supposedly eventual conferred
           | immunity, not physically being ill. No reason to think you
           | need to be sick to benefit.
        
         | candiddevmike wrote:
         | The hygiene hypothesis is tenuous at best and dangerous
         | (especially for immunocompromised peers!) at worst:
         | https://publichealth.jhu.edu/2022/is-the-hygiene-hypothesis-...
        
           | elevatedastalt wrote:
           | Hardly anyone even thinks about peanut allergies in a nation
           | of 1.4 billion people (India) and kids don't drop dead like
           | flies here.
           | 
           | But sure, let's just call the hygiene hypothesis tenuous.
        
             | candiddevmike wrote:
             | That's not at all the same thing.
        
             | yreg wrote:
             | Peanut allergy prevalence in India seems to be 0.3%, while
             | in the western countries it's 1.5-3%.
        
             | kylehotchkiss wrote:
             | Or even seasonal allergies to like pollen too, right?
             | There's just much more pressing breathing related issues to
             | be concerned with (AQI etc)
        
             | bn-l wrote:
             | A: different genes, B: Different reporting standards, C:
             | different access to healthcare for it to be reported
        
             | elric wrote:
             | I thought the recommendation was to introduce some peanuts
             | at an early age in order to reduce the risk of getting
             | peanut allergies?
        
           | actuallyalys wrote:
           | Like your article states, there's some evidence for exposure
           | to _benign_ microbes reducing _allergies_ , but that is
           | completely different than pathogens strengthening the immune
           | system. Unfortunately some people seem to have remembered the
           | hygiene hypothesis as meaning that microbes of all kinds are
           | actually good.
           | 
           | There's also a concept of immunity debt, although that's more
           | of an explanation for certain diseases being especially bad
           | the year following COVID restrictions than an argument for
           | exposure.
        
           | dabedee wrote:
           | From the linked article:
           | 
           | "Almost no virus is protective against allergic disease or
           | other immune diseases. In fact, infections with viruses
           | mostly either contribute to the development of those diseases
           | or worsen them.
           | 
           | The opposite is true of bacteria. There are good bacteria and
           | there are bad bacteria. The good bacteria we call commensals.
           | Our bodies actually have more bacterial cells than human
           | cells. What we've learned over the years is that the
           | association with family life and the environment probably has
           | more to do with the microbiome. So one thing I would say is
           | sanitizing every surface in your home to an extreme is
           | probably not a good thing. Our research team showed in
           | animals that sterile environments don't allow the immune
           | system to develop at all. We don't want that."
        
             | jph00 wrote:
             | Commensal bacteria are generally not airborne, whilst
             | viruses that harm the immune system often are. So surface
             | hygiene can be overdone, but air hygiene is a good idea.
        
         | Arnt wrote:
         | That sounds plausible, but do you think it's better to be more
         | sick than less?
         | 
         | Or do you just think that having a few sick days per year is
         | better than marching into work no matter what state you're in?
         | A very different proposition.
        
           | nradov wrote:
           | I suspect it's probably better to shift the sick days earlier
           | in life. We probably can't significantly reduce the total.
           | There are hundreds of endemic upper respiratory viruses and
           | we all eventually get infected with most of them. It's just a
           | matter of time. Our immune systems generally degrade as we
           | age, so over the long run it's probably better to get
           | infected when we're younger so that we can build immunity
           | that protects us when we're older.
        
             | coryrc wrote:
             | > We probably can't significantly reduce the total
             | 
             | That's ridiculous. During the crisis times of covid, the
             | incidences of other communicable disease dropped
             | significantly. Plus, to be frank, this is just an idiotic
             | suggestion with zero reasons to think there's some set
             | number of days people are sick. Before having kids in
             | daycare I was rarely sick. I had a child not in daycare and
             | was never sick. Now we're sick all the time, which wouldn't
             | happen if my wife could stay home with them or we didn't
             | have kids.
        
               | nradov wrote:
               | That's ridiculous. The interventions put in place during
               | the crisis times of COVID were obviously unsustainable.
               | When restrictions were lifted, the incidence of all other
               | types of respiratory viruses spiked up.
               | 
               | I've had kids in daycare as well. Occasionally you get
               | the sniffles. So what.
        
               | Izkata wrote:
               | "Other" meaning "flu", which only dropped because they
               | stopped tracking it to give resources to SARS-CoV-2.
               | There was a note on the CDC website that very few people
               | actually noticed, and almost all claims of reduced
               | transmission used the CDC's FluView as their evidence.
        
             | pjc50 wrote:
             | > We probably can't significantly reduce the total
             | 
             | We can and we have. Through things such as the measles
             | vaccine.
             | 
             | People forget that child mortality used to be a thing.
        
               | nradov wrote:
               | Sure, childhood immunization is great but we're not
               | discussing measles here. Measles is a single, relatively
               | stable virus that's easy to vaccinate against. But
               | children in daycare facilities mostly get infected with
               | upper respiratory viruses. There are literally hundreds
               | of such endemic viruses, especially rhinoviruses but also
               | coronaviruses and others. We aren't likely to have
               | effective vaccines against those any time soon. If
               | children aren't exposed to them in daycare then they'll
               | be exposed somewhere else. Those viruses aren't going
               | away and will continue circulating through the population
               | no matter what we do.
        
         | _dain_ wrote:
         | Immune system won't help against air pollution from traffic and
         | factories and forest fires.
        
         | Etheryte wrote:
         | This oversimplifies the original idea behind what you're trying
         | to recall. Being sick in and of itself is not the beneficial
         | part, it's exposure that can be beneficial in certain cases. If
         | you can get the exposure without actually falling ill it's all
         | the better, it's a win-win. Note that not all exposure is good,
         | for example you never want to be exposed to the bubonic plague
         | if at all possible.
        
         | duxup wrote:
         | They're still getting sick.
        
         | switch007 wrote:
         | I've had COVID multiple times and each time my immune system
         | takes a bigger and bigger battering, leading to many other
         | issues.
         | 
         | Are the benefits of this theory meant to start appearing any
         | time soon...?
        
         | lbrito wrote:
         | Don't worry, there will still be plenty of sickness. The
         | article says 1/3 reduction. If you have kids, you'll know that
         | the resulting number of sick days is still huge.
        
       | LinuxBender wrote:
       | Anecdotally can vouch for air purifiers. I bought an old earth
       | bermed home. I suspected radon may be an issue. Purchased 2
       | AirThings and they were off the government charts so to confirm
       | Radon Daughters were being produced I bought more air purifiers
       | and an Alpha Geiger Counter. I can hold it 2 inches from any of
       | my filters and the alarm sounds. 640 CPM alpha radiation. That
       | changed my project priorities. The filters only bought me some
       | time as the air away from the filters is the same level of
       | radiation as outdoor background noise but obviously the source is
       | still emitting gas. I will probably just bulldoze this place.
        
         | ComputerGuru wrote:
         | Radon mitigation systems work. And they're cheap.
        
           | LinuxBender wrote:
           | You're right but it won't help in my case. I created an ad-
           | hoc system that does the same thing but the source is not at
           | ground level. Through some form of convection _I suspect
           | around the chimney_ the gas is being pushed into the attic
           | and then coming down in rooms they did not join the wall to
           | the ceiling correctly. Most of the radioactive dust is being
           | produced in the attic which nobody has touched for 60+ years.
           | If I put the geiger counter in the attic it goes nuts. I 'm
           | just going to level this place and build something correctly.
        
             | ComputerGuru wrote:
             | That sounds wild. I don't know where you are but in the USA
             | you could reach out to a university extension
             | program/office and ask them to look into it. It's bizarre
             | enough to catch their interest and come at no cost to you.
             | 
             | Edit: it really is bizarre because Radon is primarily
             | produced by reactions underground/in the earth and has a
             | relatively short half life (3.5 days). I don't see how it
             | could be atmospherically sourced without it being a hazard
             | to the whole community, regardless of the bizarre
             | convection currents that bring it into your house. It's
             | unlikely to be produced in your attic.
             | 
             | If I were you, I'd want to know more and understand how
             | this is all happening lest you raze and rebuild and find
             | you still have a problem.
        
               | rightbyte wrote:
               | Some forms of uranium rich slate when mixed into concrete
               | can dispose radioactive gases.
        
               | rini17 wrote:
               | Radon decays into other longer lived radioactive
               | elements, mostly isotopes of lead, which then condense
               | down as dust and cause more problems than radon itself.
               | So it might happen that these cumulate in the attic if
               | circulation is just right.
        
               | amluto wrote:
               | Can you share your math? Radon does indeed have extremely
               | nasty decay products, but they are very short lived
               | (which is why they're so nasty). They're not accumulating
               | in your attic.
               | 
               | I would suspect fly ash as a possible source if the house
               | ever had a coal-burning furnace. Or maybe someone had a
               | watch-painting operation or mixed radioactive glazes or
               | paints there. Someone with appropriate equipment could do
               | a much better job identifying the source.
        
             | Vecr wrote:
             | Have you done the risk calculations? Are you assuming LNT?
             | Really, at the construction costs now you could probably
             | pay someone to do it and have that be profitable.
        
             | pbowyer wrote:
             | With the mention of "radioactive dust" are you sure it's
             | radon, as that should not produce dust, and not some other
             | source of radiation in the attic? Like I don't kow what, a
             | lot of old gas mantle filaments.
             | 
             | Any notion of whether it's b or g radiation you're
             | detecting?
             | 
             | Demolition is going to need careful monitoring to ensure
             | you don't contaminate the entire site.
        
       | thinkcontext wrote:
       | If borne out this is pretty big. A huge amount of productivity is
       | lost by parents taking care of sick kids or who get sick from
       | their kids. Further it might even lessen the overall spread of
       | seasonal diseases.
        
         | readthenotes1 wrote:
         | If it reduces the strength of the child's immune system, this
         | may rebound in horrible ways
        
           | pjc50 wrote:
           | There's no good evidence for "you need to get sick in order
           | to have a healthy immune system", and it leads to dangerous
           | nonsense like measles parties.
        
             | The28thDuck wrote:
             | Silly question: how does an immune system get "trained"? I
             | imagine some of it is through familial transmission but
             | getting sick seems to kick it into high gear.
        
               | loloquwowndueo wrote:
               | Vaccines. Vaccines teach your immune system to fight
               | specific viruses.
        
               | calmbonsai wrote:
               | Ideally, their own mother's milk.
        
               | jacoblambda wrote:
               | So this is an extremely simplified answer but essentially
               | some pathogen gets into the body. If they find a cell
               | first, they generally get to do their job and try to kill
               | the cell and replicate. But if a macrophage (a type of
               | white blood cell) finds them first betfore they've
               | intruded upon a cell, the macrophage eats it and
               | disassembles it into little tiny pieces.
               | 
               | The macrophage then hands over some of the important
               | pieces to undifferentiated T cells. Those T cells then
               | "differentiate" into one of two forms.
               | 
               | The first are "Helper T cells" which carry the "design"
               | for antibodies (immunoglobulins, i.e. proteins that bind
               | to pathogens directly. These then share those antibody
               | designs with B-Cells.
               | 
               | The other type are "Killer T cells" which carry the
               | "design" for T-cell-receptors that can detect "sick"
               | cells for this specific pathogen or defect. They go hunt
               | after the specific cell and essentially cause them to
               | explode with the power of hydrogen peroxide. Then the
               | macrophages eat up the dead infected cell and all the
               | pathogens inside it and start the process anew.
               | 
               | Now those B-Cells get the "design" for antibodies from
               | the helper T cells and differentiate into two types.
               | 
               | The first is essentially a factory that mass produces the
               | antibodies and dumps them into the body. Those antibody
               | proteins then bind to the pathogens and the macrophages
               | can then directly attack the pathogens (because they have
               | a bunch of big flags/alarms on them).
               | 
               | The other type of B-Cell that they can differentiate into
               | are memory B-cells. These keep the designs stored inside
               | them and keep detectors for the pathogen on their cell
               | membrane. Then they "go to sleep" until their detectors
               | are activated by the pathogen. They live out their lives
               | and replicate as needed to continue their lineage. When a
               | pathogen shows up, they bind to either the pathogen
               | directly or to some of the proteins it produces and they
               | turn their factories on at full speed and start mass
               | producing antibodies to start the immune response as fast
               | as possible locally before the pathogen can do damage.
               | They get depleted in this effort of course but if things
               | go okay, the following immune response should trigger the
               | creation of more memory B cells. (and when they don't you
               | get stuff like immune amnesia).
               | 
               | There are also "memory T-cells" but how they come about
               | and how exactly they work is fuzzy and not super well
               | understood. It's similar to memory B-cells but it's way
               | more complicated and a bit "magic".
               | 
               | But yeah eventually then your body beats the infection
               | and things go back to normal with the memory cells
               | hanging out in the body.
               | 
               | Now the important thing with intensity of infection is
               | that a mild infection will generally guarantee your body
               | learns a sane, moderate response but a major infection
               | can send your body into a panic and put the immune system
               | into overdrive. That can train a response that attacks
               | the pathogen but also attacks a lot of other stuff in the
               | process (auto-immune response).
               | 
               | You can think of this kind of like an analog version of
               | machine learning on proteins (the training input). A bad
               | fit can end up mischaracterizing healthy cells and bodily
               | structures as "pathogens" and cause long term issues or
               | even just severe reactions when you get a reinfection.
               | 
               | Now for getting "trained" from the parent, this happens
               | during pregnancy by diffusion of a subset of the
               | antibodies from the mother to the fetus (not all types
               | can but many do). Those stick around for a good while and
               | eventually the child gets minor exposure to various
               | pathogens and those shared antibodies kickstart the
               | child's immune response enough to build up its own
               | memory.
               | 
               | Hope this helps.
               | 
               | https://upload.wikimedia.org/wikipedia/commons/4/41/Prima
               | ry_...
        
             | DiggyJohnson wrote:
             | There's a lot of evidence that exposure is required for
             | immunity. That's how immunity works, no?
        
               | thebruce87m wrote:
               | Maybe there is still exposure, but at a lower viral load?
        
               | api wrote:
               | In the extreme there is evidence that _no exposure_ to
               | pathogens might weaken immunity, but that is not going to
               | be a problem unless someone is living in a bubble or on a
               | space station.
        
               | maxerickson wrote:
               | The other poster made a statement about the strength of
               | the immune system. I don't think there's much evidence
               | that exposure to virus A ends up contributing to a robust
               | response to virus Z. There's some benefit if the
               | infections are somewhat related, but not if they are
               | dissimilar. So sure, exposure to a particular infection
               | is likely to make your immune system more responsive to
               | that infection, but it's probably not reasonable to say
               | that it has gotten stronger.
               | 
               | And then, measles in particular can actually damage
               | existing immunity to other infections, making exposure to
               | it quite a lot more dangerous than just the immediate
               | infection. https://asm.org/articles/2019/may/measles-and-
               | immune-amnesia
        
               | DistractionRect wrote:
               | This is what they were talking about, exposure __does not
               | require__ you get sick. You can still be exposed, but you
               | don't need to let the concentrations of pathogens to
               | build up in stale air over the course of a school day.
               | 
               | The results aren't in yet, and of course will be subject
               | to reproduction/duplicatation, but I suspect that's what
               | we're seeing here. People (children) are still getting
               | sick, just less so, presumably because they're getting
               | exposed to lower concentrations of pathogens. The article
               | doesn't make it clear (or I missed it) if the reduction
               | is in severity (time spent recovering from being sick),
               | frequency (number of times one gets sick), or a
               | combination thereof. If I'm right, I'd expect it to be a
               | reduction stemming from both reduced frequency/severity.
        
               | dv_dt wrote:
               | There is a lot of evidence that exposure to Covid induces
               | long term permanent damage to tissue and the ability of
               | the immune system to fight off other infections.
        
               | ClumsyPilot wrote:
               | > There's a lot of evidence that exposure is required for
               | immunity
               | 
               | Think about - immune system evolved over millions of
               | years, is it plausible that it needed wild tribes of
               | hunter gatherers to huddle in a nearly airtight box for 8
               | hours and infect each other to work
        
             | sitkack wrote:
             | I think measles parties are hold over from before the
             | advent of the measles vaccine (early 1970s). Now that we
             | have a vaccine for it, the vaccine is vastly superior for
             | many reasons.
             | 
             | https://www.phind.com/search?cache=va2btahy5d5gjx0ejd888ue5
             | 
             | https://historyofvaccines.org/history/measles/timeline
        
               | pjc50 wrote:
               | Still a problem: https://inews.co.uk/news/measles-
               | parties-risk-children-life-...
               | 
               | Vaccine misinformation has been a disaster.
        
           | bluGill wrote:
           | The immune system isn't a muscle.
        
             | ipsum2 wrote:
             | Memory B and T cells would disagree with you. This is the
             | basic knowledge for how vaccines work.
        
               | jph00 wrote:
               | They would not disagree with you after, say, a measles
               | infections, which thoroughly destroys the immune system
               | at many levels.
               | 
               | It's not a good idea to confuse the impacts of vaccines
               | and infections. Vaccines are carefully developed
               | specifically to help the immune system. Viruses evolve to
               | hurt it.
        
           | nemonemo wrote:
           | "sick days reduced by a third" does not seem to be a level of
           | reduction that could induce a problematic rebound.
        
           | Terr_ wrote:
           | What you've written is unproven, and I see two facets of
           | confusion:
           | 
           | First, there's a huge difference between "strong" immune
           | responses and "good" immune responses.
           | 
           | Triggering the adaptive immune system is dangerous, like
           | unleashing Skynet robots against a zombie apocalypse. You
           | don't nuke a city at the first police report of one person
           | biting another. Your body has a ton of cascading safety
           | interlocks to try to avoid triggering more than is absolutely
           | necessary.
           | 
           | Second, there's a difference between "we need dangerous
           | exposure to actual pathogens" versus "we need calibration
           | against a mileu of benign species we co-evolved with."
           | 
           | There's no evidence our immune systems are somehow "weaker"
           | than our ancestors', but they do seem to be miscalibrated and
           | trigger-happy.
        
             | sitkack wrote:
             | There _are_ immune system benefits to vaginal delivery
             | which is primarily about the the transfer microbiota from
             | the mother to the child.
             | 
             | I am not disagreeing with anything you are saying, but
             | often these are often conflated.
             | 
             | https://www.phind.com/search?cache=f5pj4u7f9v0y8ri853qmaxg1
        
               | thelastparadise wrote:
               | What is the primary source of the bacteria? Is it somehow
               | the vagina/labia itself?
               | 
               | It seems C-section would have about as much overall fluid
               | exchange, if not more.
        
               | amanaplanacanal wrote:
               | I believe some of it is from the rectum, which you
               | wouldn't get from a c-section.
        
               | chongli wrote:
               | No, it's the vagina itself which is heavily colonized
               | with bacteria (lactofermenting bacteria and friends).
               | With a C-section you're removing the baby directly from
               | the amniotic sac into the world.
        
             | MichaelZuo wrote:
             | Practically 100% of children will have "dangerous exposure
             | to actual pathogens" multiple times before they turn 20.
             | 
             | If parents only get a choice as to when, I think nearly all
             | would choose for them to be exposed younger and before the
             | critical high school/college years, when the stakes are
             | much higher.
        
               | cogman10 wrote:
               | When a disease is dangerous depends a lot on the specific
               | disease. Measles for an adult is mostly a non-issue.
               | Measles for a child carries a high risk of deafness and
               | blindness. Chickenpox for an infant can be deadly, for a
               | child is normal, and for an adult man can cause
               | sterility.
               | 
               | There's no blanket "best time" to get sick with an
               | infectious disease. And some diseases, like chickenpox,
               | later surface as painful shingles (which in the worst
               | case can result in permanent nerve damage).
               | 
               | The best thing to do is vaccination. It's safe for the
               | vast majority of the population and sidesteps
               | complications completely. Get your flu shot.
        
               | bugglebeetle wrote:
               | It's funny on how we can be on a site where people spend
               | all day working on how to account for things like dynamic
               | conditionals, but immediately become absurdly reductive
               | and incapable of applying the same logic to anything
               | outside software. Real life also has a lot of if
               | statements!
        
               | cogman10 wrote:
               | Life is a bunch of statistics and probabilities and we
               | humans have a strong tendency to want to simplify those
               | away. We are further very naturally bad at stats
               | (probably due to our amazing pattern finding abilities).
               | 
               | Heck, I think what makes a programmer good is something
               | that can easily get in the way of fields like medicine.
               | Good programmers like to create abstractions to put
               | things into neat boxes. Programming is an exercise in
               | generalization and specialization and, unfortunately,
               | that can drive people to thinking "Oh, these diseases are
               | alike so lets put them in the same box". That
               | particularly gets in the way because MOST people won't
               | experience complications from illness. Consider measles
               | blindness, 30 million people get measles a year, 60,000
               | will get blindness. That's a 0.2% chance of developing
               | blindness as a result of measles (1 in 500). That can
               | lead to unfounded skepticism because your observed
               | reality "I don't know anyone that's been blinded by
               | measles!" might make you think that the risks are lower
               | than they are.
               | 
               | And, heck, as a programmer if you have a method that
               | fails at 1 in 500 cases you might even be justified in
               | punting fixing that thing.
        
               | bugglebeetle wrote:
               | > And, heck, as a programmer if you have a method that
               | fails at 1 in 500 cases you might even be justified in
               | punting fixing that thing.
               | 
               | I don't necessarily disagree, but if I intentionally
               | ignored a fix to a method that resulted in a service-
               | level equivalent to a user going blind every 1 in 500
               | times it ran, I'd get fired pretty quickly. But then
               | again, I have also met many programmers who, when
               | presented with such cases, pretend they do not exist.
        
           | jph00 wrote:
           | This is a common misunderstanding of the poorly-named
           | "hygiene hypothesis". For a fuller explanation of how
           | immunologists think about this today, see this article:
           | https://rachel.fast.ai/posts/2024-08-13-crowds-vs-friends/
           | 
           | In short - viruses can actually harm your immune system and
           | lead to long term problems. OTOH, we co-evolved with certain
           | parasites that can help us.
           | 
           | Airborne pathogens are not likely to be the helpful type
           | we've co-evolved with -- they're much more likely to be the
           | type we've only had to deal with since the creation of higher
           | density living and rapid long distance travel. Therefore air
           | filters are likely to help children's health both short and
           | long term.
        
             | dennis_jeeves2 wrote:
             | To sort of complement what you are saying, the 'hygiene
             | hypothesis' also ends up being a an excuse for not looking
             | at other factors. (very similar to blaming genes alone for
             | health issues)
        
       | thrance wrote:
       | I'd like to see the study first, how can we know that this year's
       | flu variant wasn't just less infectious ? What was the sample
       | size ? What's the p-value ?
        
         | Retric wrote:
         | I get your concern, but large effect sizes make up for a
         | multitude of sins.
        
         | vhcr wrote:
         | Flu variants infectionness variability is just a so well known
         | variable that the researchers would have to be really mediocre
         | to not take that into account, the official press release
         | mentions they're performing the studies on four kindergartens,
         | so they're most probably comparing against each other.
         | 
         | https://www.pandemicresponse.fi/post/can-the-spread-of-flu-b...
        
       | lurking_swe wrote:
       | have we learned nothing from the covid pandemic?
        
         | pjc50 wrote:
         | Evidently not. There was lots of early good results on air
         | purification and UV, but there was absolutely no action or even
         | official advocacy as a result.
        
           | mdp2021 wrote:
           | Probably a matter of cost. E.g. in some territories
           | plexiglass screens were put everywhere between clerks and
           | customers - as a measure that was considered more easily
           | mandated and done (basically, simply cheaper) than modifying
           | air treatment infrastructure.
        
         | elric wrote:
         | What do you mean?
        
       | _dain_ wrote:
       | This is one of the three educational interventions with solid
       | evidence of it working. The other two are air conditioning and
       | free school lunches. People don't get excited over them though,
       | because they have nothing to do with teachers or curriculum or
       | educational theory.
        
         | stevenwoo wrote:
         | There's also the accidental study of air filters where the
         | outside air quality was not that bad. study
         | https://www.edworkingpapers.com/ai20-188 background
         | https://wfis.org/installing-air-filters-in-classrooms-has-su...
        
           | amluto wrote:
           | Wow. That paper made no effort to even contemplate whether
           | the improvement was related to reduced particulate matter or
           | to reduced organic gasses. The filters were installed in
           | response to a _gas_ leak -- one would imagine they were
           | carbon filters.
           | 
           | Sadly, the literature on the effect of gas concentrations on
           | human intellectual function is incredibly muddy.
        
         | mmcloughlin wrote:
         | Perhaps there is some evidence that people do get excited about
         | free school lunches: Governor Tim Walz's lunch policy in
         | Minnesota has been a part of the buzz surrounding his recent
         | Vice Presidential nomination.
         | 
         | https://www.cnbc.com/2024/08/19/universal-free-school-lunche...
        
         | olalonde wrote:
         | > free school lunches
         | 
         | What are you referring to?
        
           | pjc50 wrote:
           | They're referring to free school lunches. That is, a lunch,
           | at school, which is free. In the sense that it does not have
           | to be paid for on the spot or by the child or family on
           | account. i.e. part of the educational provision itself.
           | 
           | (carefully phrased to avoid "no free lunch" nonsense)
        
             | olalonde wrote:
             | I understand, I meant what solid evidence that it is
             | working?
        
       | photochemsyn wrote:
       | I wouldn't call this a statistically significant result, and the
       | fact that the buildings in question had good mechanical air
       | ventilation could very well explain the results:
       | 
       | > "Utilizing the model, we used portable air cleaners in two day
       | care units (A and B, number of children participating in the
       | study n = 43) and compared infection incidents between the two
       | intervention units to the rest of the units in city of Helsinki
       | (n = 607). The intervention buildings had mechanical supply and
       | exhaust air ventilation."
       | 
       | https://www.sciencedirect.com/science/article/pii/S295036202...
       | 
       | You also have to consider external air quality, as ventilating a
       | building with polluted air would have negative effects like
       | increased asthma. In that case perhaps a sealed building with air
       | purifiers is a better option, but then CO2 buildup is a concern,
       | so you'd need CO2 scrubbers, which are expensive.
       | 
       | That's why clean air regulations matter, and getting off fossil
       | fuel combustion as an energy source (and limiting
       | pesticide/herbicide use in agricultural zones) is the easiest
       | route forward.
        
       | elevatedastalt wrote:
       | Could this be combined with masks for greater efficacy?
        
         | bluGill wrote:
         | Most likely but nobody will allow you to suggest that.
        
           | roywiggins wrote:
           | Kids of daycare age probably can't wear masks effectively
           | enough to make a difference, and if they can, it's not
           | obvious that it's worth the effort.
           | 
           |  _Adults_ could probably reduce how many colds they get by
           | wearing masks everywhere, but most people don 't think it's
           | worth the effort.
        
         | dumbo-octopus wrote:
         | Masks have directly contributed to a speech development
         | epidemic amongst youth who were deprived of their ability to
         | see and mimic mouth movements during their prime developmental
         | stages. This has hit underprivileged kids who do not have
         | english spoken at home especially hard. Masks aren't free.
        
           | maeil wrote:
           | Is there research that shows this? Should be incredibly easy
           | to prove given a large percentage of the world consistently
           | masked and another large percentage of the world consistently
           | did not mask.
           | 
           | For reference, I live in a country that had one of the
           | highest masking rates in the world (probably top 10), and
           | this does not seem to be an issue here whatsoever. Not a
           | single time I've heard it mentioned, and given just how huge
           | the focus on child development is here, there's no way it
           | wouldn't be a massive topic.
        
             | dumbo-octopus wrote:
             | I've spoken at length with individuals directly responsible
             | for rehabilitation of such children. But of course if the
             | facts go against the government narrative, the "studies"
             | will not report them. Talk to people, not studies.
             | 
             | Do you have many cases of children being in homes where
             | they have limited access to people speaking the national
             | language? Do you talk to individuals who are directly
             | responsible for teaching those folks the language?
        
               | maeil wrote:
               | I think it was clear from my comment that I haven't heard
               | a single person (not just study) here talk about it.
               | 
               | While it's reasonable such an adverse effect would be
               | stronger in cases where at home a different language is
               | spoken than the national language, it's very unlikely
               | that it would _only_ have a noticeable effect for exactly
               | those families, with zero noticeable effect otherwise.
               | And here, where masking rates were extremely high and
               | amount of attention put on /money spent on child
               | development is higher than almost anywhere else in the
               | world, no one has ever brought it up.
               | 
               | This doesn't even touch upon the fact that unprivileged
               | families are much harder hit by epidemics (let alone
               | Covid) in general, due to a host of other factors.
               | 
               | > But of course if the facts go against the government
               | narrative, the "studies" will not report them.
               | 
               | The studies showing that masks were incredibly effective
               | at preventing disease spread went against the US
               | "government narrative" at the time, since I imagine
               | you're talking about the US.
        
               | NorthTheRock wrote:
               | > Talk to people, not studies.
               | 
               | So literally calling for anecdotes over data?
        
               | dumbo-octopus wrote:
               | Anecdotes are data.
        
               | dumbo-octopus wrote:
               | "Data" is anecdotes obfuscated and p-hacked to fit the
               | narrative the reviewers mandate. Anyone who has published
               | in journals knows this.
        
           | terminatornet wrote:
           | not true
           | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9637007/
        
             | dumbo-octopus wrote:
             | I've talked to the boots on the ground. Government
             | scientists publishing the official narrative are useless.
        
               | immibis wrote:
               | Why can't you provide any information, then?
        
               | dumbo-octopus wrote:
               | I just did. The specifics are of course confidential
               | personal information from minors, you want me to publish
               | them here?
        
               | terminatornet wrote:
               | source: trust me
        
               | dumbo-octopus wrote:
               | Even if you do elect to trust the government mandated
               | studies more than the special education teachers directly
               | involved in the situation, the very study the parent
               | cited attempting to discredit me also reaches the same
               | conclusion as me: masks cause developmental damage and
               | their use must be carefully considered, especially as it
               | pertains to forcing young children who can't say "no" to
               | comply.
        
               | jbm wrote:
               | I'm sympathetic to your views about government policies
               | manipulating which items get studied (see: previous
               | conservative Canadian government muzzling scientists who
               | made comments about oil)
               | 
               | I also agree that personal anecdotes from trusted parties
               | are more valuable to my decision making than "data" --
               | but those are personal anecdotes, not anecdotes from
               | anonymous Internet personas.
               | 
               | We aren't your friends and we don't know you. Why should
               | we trust you if you are vaguebooking about something that
               | is a common conspiracy trope?
        
         | PaulKeeble wrote:
         | N95/FFP2 Masks are even higher effectiveness. Even just one
         | wearer can often avoid infections for years if the mask is used
         | and fitted well. If most people are wearing them we would wipe
         | out most respiratory disease spread. They are ridiculously
         | effective and it's why they have been used in hospitals for
         | decades when dealing high contagious conditions.
        
         | tgsovlerkhgsel wrote:
         | Certainly, but the cost (in this case probably even the
         | _actual_ cost, but mostly in terms of impact on everyday life)
         | is vastly higher with masks - they 're inconvenient and
         | annoying, and make social interaction harder.
         | 
         | Meanwhile, air purifiers use a bit of power (probably less of
         | an environmental impact than the inevitable littering of masks
         | which are basically all microplastic while looking like
         | harmless paper), probably cost less per filter change than a
         | week's supply of mask, and have a relatively negligible comfort
         | impact.
        
       | encoderer wrote:
       | Even better (where weather allows) is fully outdoor daycare. We
       | were fortunate to have only the briefest of shut downs during
       | COVID.
       | 
       | Obviously impractical in many areas but it's part of the
       | California dividend
        
         | Rendello wrote:
         | It was a big thing in the early 1900s too:
         | 
         | https://en.wikipedia.org/wiki/Open_air_school
        
         | esafak wrote:
         | And it's good for your eyesight.
        
           | euroderf wrote:
           | Yes. Lots of new results in this topic. Get outside and
           | exercise those eyes.
        
         | kjkjadksj wrote:
         | So long as you are far enough from a major freeway, major road,
         | major airport, or major port. With those requirements the
         | number of californian daycares or schools that meet that
         | criteria shortens significantly.
        
       | modeless wrote:
       | Near UV seems really promising for preventing indoor disease
       | transmission as well. Has there been any more research on it
       | lately?
        
         | amluto wrote:
         | Do you mean far-UVC, around 222nm? It seemed like the major
         | issues were the sources being expensive, the sources being from
         | dubious vendors with no standard certification (I would be
         | concerned that my "222nm" source might have a lot of
         | inadvertent emission at other wavelengths), and possible damage
         | over time to whatever you aim it at.
        
           | PaulKeeble wrote:
           | The bulbs only last maybe 1000 hours as well which combined
           | with their price narrows their usage.
        
           | modeless wrote:
           | Yes. Those problems seem relatively easy to fix compared to
           | the immense benefit of a significant reduction in disease
           | transmission across the board.
        
         | emeril wrote:
         | isn't UV light dangerous for people?
         | 
         | perhaps there's certain wavelengths that kill viruses/bacteria
         | but don't increase cancer risk?
        
           | PaulKeeble wrote:
           | 254nm is used as part of GUV and it's not good for people and
           | black out blinds are used in hospitals where they are
           | installed when sanitising. Far UV 222nm is not damaging to
           | humans that we know of but it's a peak of destruction for
           | viruses, bacteria and fungus.
        
       | duxup wrote:
       | Is there any information on the type / price of these air
       | purifiers?
       | 
       | There's a lot of "air purifiers" out there on the market.
        
         | PaulKeeble wrote:
         | In a lot of tests Corsi Rosenthal boxes tend to outperform most
         | commercial offerings and they are very cheap as they are a box
         | fan duct taped to some MERV13 filters. Effectiveness is a lot
         | about air exchanges an hour.
        
           | amanaplanacanal wrote:
           | I have one of these set up on each floor of my two story
           | house to cut down on particulates from dust, pets, and
           | cooking. If they also help protect from disease that's just
           | icing in the cake.
        
           | djmips wrote:
           | Box fans are noisy and in my experience fail early when
           | running constantly. When their bearings fail they can atomize
           | the grease.
        
         | amluto wrote:
         | It would be awesome if they were IKEA purifiers. Cheap media
         | and excellent CADR/W.
        
       | plasticchris wrote:
       | With my experience around poorer schools in the USA I would worry
       | that the filter wouldn't get replaced for decades and itself
       | become a breeding ground for molds.
        
       | PaulKeeble wrote:
       | There has been a number of these studies in schools and hospitals
       | showing HEPA filters reduce up to about 2/3rd of infections. We
       | now know many viruses are airborne including Covid and Al
       | Hubbard's studies on how long virus is viable has shown it can be
       | hours and it's helped by high CO2. Air circulation and reducing
       | CO2 makes a big difference as well.
        
         | lolinder wrote:
         | Do we have evidence that CO2 is causal or is it still just a
         | correlation? In general, poor ventilation + humans = high CO2,
         | so unless there was a controlled experiment done that's a
         | pretty strong confounding factor.
        
           | icelancer wrote:
           | CO2 in terms of illness is merely a proxy for good air
           | movement and exposure to the outside environment. It has its
           | own impact on mental capacities of course.
        
           | rockinghigh wrote:
           | > Results showed increasing the CO2 concentration to just 800
           | ppm, a level identified as well ventilated, resulted in an
           | increase in viral aerostability. After 40 minutes, when
           | compared to clean air, around 10 times as much virus remained
           | infectious when the air has a CO2 concentration similar to
           | that of a crowded room (3,000 ppm).
           | 
           | > Dr Haddrell said: "This relationship sheds important light
           | on why super spreader events may occur under certain
           | conditions. The high pH of exhaled droplets containing the
           | SARS-CoV-2 virus is likely a major driver of the loss of
           | infectiousness. CO2 behaves as an acid when it interacts with
           | droplets. This causes the pH of the droplets to become less
           | alkaline, resulting in the virus within them being
           | inactivated at a slower rate.
           | 
           | https://www.bristol.ac.uk/cabot/news/2024/virus.html
           | 
           | Ambient carbon dioxide concentration correlates with SARS-
           | CoV-2 aerostability and infection risk
           | 
           | https://www.nature.com/articles/s41467-024-47777-5
        
             | lolinder wrote:
             | Thanks! This is exactly what I was looking for.
        
           | LordKeren wrote:
           | I have never seen a evidence that CO2 is a casual agent of
           | disease (extremely obvious exceptions excluded)
        
         | dzhiurgis wrote:
         | Do you still need HEPA/air purifier if you have decent ERV/HRV?
        
       | xyst wrote:
       | Any HVAC professionals or plumbers know if a mini-split A/C
       | system can be outfitted with UV bulbs?
       | 
       | Have a few Levoit air purifiers that sit flush against the wall.
       | But would be nice to have an extra layer at the source.
        
       | Fire-Dragon-DoL wrote:
       | This would he huge. Aside from the huge benefit, it would be
       | great not having runny nose or cough 6 months of the year.
        
       | elric wrote:
       | I installed a Zehnder ComfoAir Q ventilation system in my home.
       | It has heat and moisture recuperation capabilities. It's
       | currently refreshing the air at around 100m3/hour. It has an F7
       | (aka "ISO Fine" or "MERV 13") filter. Since installing it, my
       | asthma has improved a fair bit, and I'm sneezing a lot less.
       | Added benefit, virtually no mosquitoes have been able to enter my
       | home. I'm still considering getting an extra filter addon to
       | filter out more fine soot from car exhaust etc, but even without
       | that option I've been very happy with the results.
       | 
       | Edit: hit reply too soon. Wanted to add: are air purifiers as
       | effective as increased ventilation? Should we combine the two?
        
         | turtlebits wrote:
         | Get an AQ monitor and a standalone filter, it will be able to
         | constantly filter air vs the once during fresh air intake.
         | 
         | Also my ERV only runs on demand (~1/3 of the time, which is not
         | enough filtration)
        
           | elric wrote:
           | Why does it run on demand? Mine runs 24/7, though it ramps
           | down to lower speeds at night or when I'm away.
        
         | dzhiurgis wrote:
         | I've installed HRV myself too. I have a reasonably easy to
         | access roof space, but for a large guy still took over half a
         | day. Cost 1.5k NZD, but not mosquito free, it's warmer indoors
         | plus when neighbours fire up their fireplaces I only get an
         | occasional little whiff of it.
         | 
         | Best thing I did for my house so far!
        
       | tgsovlerkhgsel wrote:
       | It's amazing that this seems surprising to people after COVID.
       | 
       | Next up:
       | 
       | * Air purifiers in schools cut parent's sick days too (not just
       | "I need to care for my kid" days - "parent is sick" and
       | "childless coworker of parent is sick" sick days)
       | 
       | * Air purifiers in strategic locations (high density offices,
       | public transit, schools, ...) cut sick days across the
       | population.
       | 
       | I think this will be our generations "realizing that washing your
       | hands before surgery makes patients die less", and it's quite
       | embarrassing that with all the knowledge about viral transmission
       | we couldn't figure this out _before_ the pandemic, and even more
       | embarrassing that we couldn 't figure it out immediately after we
       | tested many of these things at a large scale.
        
         | mdp2021 wrote:
         | > _I think this will be our generations "realizing that washing
         | your hands before surgery makes patients die less"_
         | 
         | Surely not the same thing as Semmelweis. We want to destroy
         | microbes (and viruses) in specific contexts, not
         | indiscriminately.
        
           | pjc50 wrote:
           | > We want to destroy microbes (and viruses) in specific
           | contexts, not indiscriminately.
           | 
           | Apart from the known useful ones, like gut flora: no, we
           | really do want to destroy them indiscriminantly. We bleach
           | surfaces to do this, we can bleach air too.
        
             | jMyles wrote:
             | Let's be a little more cautious and observant in our
             | approach to antimicrobial stewardship.
             | 
             | Yes, we can bleach surfaces, but pathogens (in relatively
             | rapid terms) develop resistance [0].
             | 
             | Yes, we can reduce bacteria at factory farms to small
             | numbers with the indiscriminate use of antibiotics in
             | animal feed, but it's easy to observe that this trains
             | pathogens to avoid our most powerful chemical antibiotics.
             | 
             | And so it is with fomites, respiratory pathogens, STDs, and
             | probably even with measures to control arboviruses.
             | 
             | We live in an ecological balance, and discretion is the
             | better part of valor with regard to ensuring that this
             | ecology becomes more likely to nurture increasingly better
             | health outcomes.
             | 
             | 0: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7464077/
        
               | immibis wrote:
               | Humans actually live way outside of the ecological
               | balance point. We can move the balance point, or the
               | ecology will return us to that balance point.
        
         | JoshTriplett wrote:
         | The challenge isn't just "figuring it out"; the challenge is
         | also _actually putting it in place_ even knowing that. Because,
         | astonishingly, there seem to be _actual people against the
         | concept of air purification_. (Just read through this comments
         | section.)
         | 
         | There were doctors and surgeons against the concept of
         | handwashing, too, but fortunately they lost. Unfortunately, it
         | took a long time for them to lose, and a lot of people died as
         | a result. How do we skip that part?
        
           | mdp2021 wrote:
           | > _air purification_
           | 
           | <<Air purification>> interpreted as "destroying all life in
           | the air you breathe"? That would be an extraordinary claim
           | and you would have to prove that it is a good idea.
           | 
           | ("Air purification" can be interpreted to be about chemical
           | and mechanical qualities, before the consideration of the
           | living entities in the air.)
        
             | jstummbillig wrote:
             | Let's go with "air purification" as in "what air purifiers
             | are supposed to effect, as observed in the study being
             | discussed in this thread"
        
               | mdp2021 wrote:
               | > _what air purifiers are supposed to effect, as observed
               | in the study_
               | 
               | Which would be? Have you seen details in the submitted
               | article? I suppose this is the study (but the page is
               | bouncing me): https://www.sciencedirect.com/science/artic
               | le/pii/S240584402...
               | 
               | I have an air purifier working not two meters from me -
               | and it is an HEPA filter with forced ventilation. Not an
               | "air disinfectant".
        
               | jstummbillig wrote:
               | Per this study, the number of sick days.
        
           | maxerickson wrote:
           | Lots of places are going to do the regulatory minimum for
           | ventilation, and I sure haven't seen any much change to
           | regulations.
        
           | schiffern wrote:
           | >fortunately they lost
           | 
           | ...only after they caused a delay of 2-3 decades, directly
           | leading to thousands of unnecessary patient deaths.
           | 
           | https://www.sciencedirect.com/science/article/abs/pii/S18788.
           | ..
           | 
           | https://www.npr.org/sections/health-
           | shots/2015/01/12/3756639...
        
             | bugglebeetle wrote:
             | Yeah and we're also going to end up with decades worth of
             | dead and disabled people to end this willful
             | ignorance/malicious stupidity. The "COVID is over" crowd
             | already demonstrated this. Bad ideas rarely die until all
             | or most of the people who have them do. And even then, only
             | sometimes!
        
               | immibis wrote:
               | This is downvoted because it is true but inconvenient.
               | Humans tend to prioritize feelings over facts - just like
               | with handwashing, "if this were true, I'd have killed
               | people, therefore it is not true."
        
             | JoshTriplett wrote:
             | Yeah, I'm very aware. I'd love to know what it'd take to
             | skip over that part.
        
           | euroderf wrote:
           | > There were doctors and surgeons against the concept of
           | handwashing, too, but fortunately they lost.
           | 
           | Did the thinking go something like "Every pathogen that does
           | not kill our patients only makes them stronger"?
        
             | schiffern wrote:
             | The controversy predates the germ theory of disease and the
             | concept of "pathogens."
             | 
             | https://en.wikipedia.org/wiki/Ignaz_Semmelweis
        
             | immibis wrote:
             | The thinking went something like "If this were true, I'd be
             | wrong, therefore it is not true."
             | 
             | and possibly "If this were true, I'd be responsible for
             | killing a hundred people, therefore it is not true."
        
               | JoshTriplett wrote:
               | Those are definitely dangerous patterns. Another
               | dangerous one doesn't even perfunctorily start with "if
               | this were true", but instead starts with dismissal as a
               | perceived status-challenge ("Bah, why would we do a low-
               | status thing?")
               | 
               | > some doctors were offended at the suggestion that they
               | should wash their hands and mocked him for it
               | 
               | The common thread in _all_ of these, though, is not
               | embracing a fundamental mindset of  "If I'm wrong I want
               | to know that and change and improve".
        
             | mminer237 wrote:
             | It was more thinking that made no logical sense and was a
             | bit of personal insult. Remember, the leading scientific
             | theory at the time was that illness was caused by bad air.
             | It would be the same as you suggesting to your doctor today
             | that he wouldn't have killed his patient if he was wearing
             | more deodorant. He would both think you are completely
             | crazy and insulting.
        
               | JoshTriplett wrote:
               | If you had evidence showing that it seems to _work_ ,
               | then whether the mechanism of action was understood yet
               | or not, they _shouldn 't_ be perceiving it as crazy or
               | insulting; they should be _doing_ it, and in parallel
               | seeking to _understand_ it.
               | 
               | (It's also possible for a study to be flawed, but even
               | then, the reaction should be to do better, not to react
               | with "crazy and insulting".)
        
         | AtlasBarfed wrote:
         | The medical establishment for years told everyone that viruses
         | were spread by contact and not by air.
        
       | throw7 wrote:
       | Indoor air environments are usually poor. Just having outside air
       | from open windows would be an improvement.
        
       | coding123 wrote:
       | I actually hope building codes eventually include some kind of
       | positive pressure system in the future where incoming air is
       | hepa'd. PPSystems tend to clean the air the most.
        
       | chriscjcj wrote:
       | Can anyone provide or link to some solid guidelines on what
       | kind/brand of air purifiers actually do real effective filtration
       | vs. garbage products? I have found that a great many of these
       | "air purifiers" have great marketing and make amazing claims.
        
         | sbochins wrote:
         | I've been happy with Austin Air purifiers. Most of the other
         | brands help, but don't handle most VOCs. If you have allergies
         | or other issues, it's better to stick with top quality brands.
         | https://housefresh.com/austin-air-healthmate/
        
         | tiahura wrote:
         | A 20" box fan and 4 20" furnace filters
        
           | Rebelgecko wrote:
           | Unless you live in a place with very cheap electricity,
           | you'll save money in the long run by getting a purpose built
           | air purifier
        
             | tedunangst wrote:
             | How much money over how much time?
        
             | alliao wrote:
             | nothing comes close to crbox in terms of performance... the
             | gold standard IQAir do give you close to perfect single
             | pass filtration but the cfm is so low and noise much
             | higher...
        
         | bjoli wrote:
         | 4x merv 13 filters.
         | 
         | A fan.
         | 
         | Now you have yourself a high performing air purifier.
        
           | ceejayoz wrote:
           | Yup. We have several of these running. Helps with allergies
           | and when one of us got COVID the rest did not.
           | 
           | https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box
        
         | alliao wrote:
         | cr box basically owns everything else go build a couple
         | yourself, it's great, if you live in the US you can order kits
         | too
        
       | retrochameleon wrote:
       | https://youtu.be/gaQTYrisieA
       | 
       | This is an extremely well researched and presented video that
       | exposes the fact that HEPA purifier marketing is a bit of a scam.
       | The most important factor in air purifiers is not the filter but
       | Clean Air Delivery Rate. You can only make a difference if you
       | are moving air through the filters faster than particulate is
       | introduced into the air.
       | 
       | I just returned a Medify filter because their advertised square
       | footage is way higher than what the purifier should support based
       | on the info in the video; it is inadequate. No idea how they are
       | calculating their numbers - not to mention it's probably at the
       | max speed setting - but it doesn't align with the sources from
       | the video.
       | 
       | On top of that, smaller air purifiers must move air faster, be
       | noisier, and the smallest sizes of particulate are captured most
       | effectively at low velocities.
       | 
       | Use something like this to make a nicer version of a CR box:
       | https://acinfinity.com/component-cooling/cabinet-fan-systems...
       | 
       | Or buy one of these: https://www.cleanairkits.com/
       | 
       | Those seem to be the best options that ACTUALLY work.
        
         | schiffern wrote:
         | Yes, almost all websites give the filter "square footage" at a
         | measly 1 air change per hour. So essentially they take the
         | CADR, divide it by the (assumed) height of the room, and that's
         | the square footage or square meters. Very flawed methodology!
         | 
         | Typically for respiratory pathogens you want to shoot for 6+
         | ACH, so as a very rough initial guess I often simply divide the
         | rated area by 10.
         | 
         | And yes, every manufacturer only gives specs for the highest
         | fan setting. This is misleading because typically this fan
         | setting is very loud, so few people actually run it 24/7 (and
         | those who do will probably suffer hearing loss).
        
       | jimberlage wrote:
       | As much as I hate the amount of illnesses my kids get from
       | daycare - maybe this shouldn't be a goal? In workplaces,
       | hospitals, etc. we definitely want to reduce illness. In
       | daycares, the kids are all building their immune systems and the
       | contact with germs is a vital part of that.
       | 
       | I definitely understand the teachers don't want to be sick, and
       | it's a hardship on parents to keep kids home, so it's not all
       | about the kids' health. But the kids' health might be better
       | served by letting them get more minor illnesses, not less.
        
         | analog31 wrote:
         | Even a third less is probably still plenty. And the putative
         | immune system benefit strikes me as hypothetical unless the
         | exposure and effect are quantified.
        
           | stoperaticless wrote:
           | What do you think about vaccines?
        
             | analog31 wrote:
             | Well, I've got all mine, unless another booster is
             | available that I don't know about. One thing about vaccines
             | is that you know exactly who got them, and who didn't. This
             | probably makes it a lot easier to study.
             | 
             | And I'm willing to believe that some childhood exposure to
             | pathogens is beneficial, but I don't think we know how much
             | of a good thing is enough, or too much.
        
         | 4fterd4rk wrote:
         | There is zero proof that this is the case.
        
         | alliao wrote:
         | I'd agree based on my own bias which appeals to nature, and
         | thus can only agree if the environment's somewhat untouched.
         | but we've introduced so much into our environment, from
         | tyre/brake dust to micro plastic to covid, I'd really much
         | rather we just clean the air. we are not anime protagonist that
         | evolve in real time, evolution in the real world consists of
         | the unfit dying, and the ones that lives reproduce etc
        
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