Study: Air purifier use at daycare centres cut kids' sick days by a third (2023)

https://yle.fi/a/74-20062381

by mji • 2 years ago

433 264 2 years ago

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• 2 years ago

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• 2 years ago

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• 2 years ago

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.

__turbobrew__• 2 years ago

An unpopular opinion: one of the parents is a full time care giver.

MikeRichardson• 2 years ago

I was a kid in daycare a lot. Also, my mom (sole caregiver, besides daycare) was a registered nurse and at the time specialized in staff (i.e, direct patient care) nursing.

No way was she sick 90% of the time, or even 10% of the time, despite the numerous alleged opportunities for infection ("daycare", staff nursing, etc).

eleveriven5• 2 years ago

And reducing the productivity loss associated with parental responsibilities could benefit everybody!

eleveriven5• 2 years ago

Schools and daycares are often places where illnesses spread quickly

switch0073• 2 years ago

Good news. Hopefully a country as wealthy as Finland can just roll this out countrywide without much thought, if not already standard

readthenotes12• 2 years ago

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

switch0073• 2 years ago

Without much thought regarding cost. Calm down lol

unsupp0rted• 2 years ago

What evidence is there that it’s possible to “exercise” an immune system?

hirsin• 2 years ago

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_logic2• 2 years ago

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.

terminatornet5• 2 years ago

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• 2 years ago

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

plasticchris2• 2 years ago

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• 2 years ago

You can use UV to sanitize water to drink? Must be better tasting than those gross iodine tablets!

amluto8• 2 years ago

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.

elric7• 2 years ago

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.

schiffern5• 2 years ago

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.

viraptor• 2 years ago

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.

slyall• 2 years ago

Naomi Wu did some videos/articles about this and was working on some sort of product you could setup. Things like a light that shone upwards in a room to clean the air above people's heads.

My main take-away was this was very easy to screw up and cause eye damage, especially in an home setting where less care would be taken.

taeric• 2 years ago

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• 2 years ago

However I think it is important for children to get sick. Humans need pathogens to train their immune system.

AwaAwa• 2 years ago

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_logic2• 2 years ago

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.

WithinReason• 2 years ago

How often and how sick? The more the better?

appplication• 2 years ago

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.

candiddevmike2• 2 years ago

The hygiene hypothesis is tenuous at best and dangerous (especially for immunocompromised peers!) at worst: https://publichealth.jhu.edu/2022/is-the-hygiene-hypothesis-...

elevatedastalt2• 2 years ago

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.

actuallyalys• 2 years ago

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• 2 years ago

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."

Arnt2• 2 years ago

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.

nradov3• 2 years ago

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.

_dain_2• 2 years ago

Immune system won't help against air pollution from traffic and factories and forest fires.

Etheryte• 2 years ago

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.

duxup2• 2 years ago

They're still getting sick.

switch0073• 2 years ago

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• 2 years ago

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.

LinuxBender4• 2 years ago

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.

ComputerGuru2• 2 years ago

Radon mitigation systems work. And they’re cheap.

LinuxBender4• 2 years ago

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.

thinkcontext• 2 years ago

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.

readthenotes12• 2 years ago

If it reduces the strength of the child's immune system, this may rebound in horrible ways

pjc506• 2 years ago

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.

bluGill2• 2 years ago

The immune system isn't a muscle.

nemonemo• 2 years ago

"sick days reduced by a third" does not seem to be a level of reduction that could induce a problematic rebound.

Terr_• 2 years ago

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.

jph003• 2 years ago

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.

DrNosferatu2• 2 years ago

They might have a point. Only anecdotes, but I hear that kids born during Covid (and therefore confinement) get a lot sicker than other generations.

Your experience?

wiether• 2 years ago

Dwight, is that you?

thrance• 2 years ago

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• 2 years ago

I get your concern, but large effect sizes make up for a multitude of sins.

vhcr• 2 years ago

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• 2 years ago

have we learned nothing from the covid pandemic?

pjc506• 2 years ago

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.

mdp20218• 2 years ago

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.

elric7• 2 years ago

What do you mean?

_dain_2• 2 years ago

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• 2 years ago

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...

amluto8• 2 years ago

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• 2 years ago

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...

olalonde2• 2 years ago

free school lunches

What are you referring to?

pjc506• 2 years ago

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)

photochemsyn• 2 years ago

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.

elevatedastalt2• 2 years ago

Could this be combined with masks for greater efficacy?

bluGill2• 2 years ago

Most likely but nobody will allow you to suggest that.

roywiggins• 2 years ago

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-octopus11• 2 years ago

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.

maeil2• 2 years ago

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.

terminatornet5• 2 years ago

not true https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9637007/

PaulKeeble5• 2 years ago

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.

tgsovlerkhgsel2• 2 years ago

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• 2 years ago

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• 2 years ago

It was a big thing in the early 1900s too:

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

esafak• 2 years ago

And it's good for your eyesight.

euroderf2• 2 years ago

Yes. Lots of new results in this topic. Get outside and exercise those eyes.

kjkjadksj• 2 years ago

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.

dzhiurgis6• 2 years ago

Unless you don't want to expose your kids to sun screen, eeek /s

modeless3• 2 years ago

Near UV seems really promising for preventing indoor disease transmission as well. Has there been any more research on it lately?

amluto8• 2 years ago

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.

PaulKeeble5• 2 years ago

The bulbs only last maybe 1000 hours as well which combined with their price narrows their usage.

modeless3• 2 years ago

Yes. Those problems seem relatively easy to fix compared to the immense benefit of a significant reduction in disease transmission across the board.

emeril• 2 years ago

isn't UV light dangerous for people?

perhaps there's certain wavelengths that kill viruses/bacteria but don't increase cancer risk?

PaulKeeble5• 2 years ago

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.

duxup2• 2 years ago

Is there any information on the type / price of these air purifiers?

There's a lot of "air purifiers" out there on the market.

PaulKeeble5• 2 years ago

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.

amanaplanacanal2• 2 years ago

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• 2 years ago

Box fans are noisy and in my experience fail early when running constantly. When their bearings fail they can atomize the grease.

amluto8• 2 years ago

It would be awesome if they were IKEA purifiers. Cheap media and excellent CADR/W.

plasticchris2• 2 years ago

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.

erikvanoosten• 2 years ago

You don't need poor schools for that. Just ~3 years ago exactly this happened to a public primary school in a rich neighborhood of Haarlem (The Netherlands). If I remember correctly, the filters had not been replaced for 8 years.

PaulKeeble5• 2 years ago

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.

lolinder2• 2 years ago

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• 2 years ago

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• 2 years ago

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

LordKeren• 2 years ago

I have never seen a evidence that CO2 is a casual agent of disease (extremely obvious exceptions excluded)

dzhiurgis6• 2 years ago

Do you still need HEPA/air purifier if you have decent ERV/HRV?

amluto8• 2 years ago

Maybe.

I have a “decent” ERV. The manufacturer claims that it’s great against air pollution, wildfire smoke, etc, and those claims do not come with numbers. Empirically (as measured by an actual particle counter), it’s crap. It does have real numbers for ventilation rate, and it works great for ventilation. This is a high end ERV, and I see no evidence that any other model is better. And it can’t be: a good, energy efficient filter is large, and all the manufacturers want their devices to be small.

My solution: put a great honking filter in front of it. This increases the lifetime of its crap internal supply filter to effectively infinity (or I could remove it), adds basically no resistance, and reduces supply particulates to effectively zero.

“Great honking” here means a 24"x24"x12" “nominal” HEPA filter with a MERV 8 prefilter. The prefilter costs basically nothing. I expect the HEPA filter to last for years. I would have preferred a not-quite-HEPA 99.5% or 99.9% filter instead, but those are surprisingly hard to buy. Big HEPA filters are easy to buy. Two big MERV 16 filters in series would do the trick, too.

(The filter efficiency math is entirely different for a ventilation system than for a recirculating filter. For recirculation, MERV 13 is fine and MERV 16 is a bit better. For once—and-done ventilation, you want to reduce outdoor crap to your preferred levels in a single pass, and MERV 13 is not even close to good enough in places with pollution or smoke issues.)

Coversely, a poorly filtered fresh air system is fine for reducing air contaminants from indoors but will actively fight against a standalone air purifier if your goal is to reduce outdoor pollutants.

eleveriven5• 2 years ago

I think using a HEPA air purifier can still be beneficial. ERV and HRV typically have standard filters that may not capture very fine particles, allergens, or airborne pathogens as effectively as HEPA filters do.

bradlys• 2 years ago

Probably depends more on the air changes per hour. You'd have to compare running a filter in your room/house and the air changes it'd go through in an hour compared to your ERV/HRV. My bet is that an ERV is better if they're the same. But, it is much easier to add capacity to individual rooms with a standalone air filter than it is to change your ERV to be higher output.

xyst• 2 years ago

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.

abracadaniel• 2 years ago

REME Halo was recommended to me and I bought one. Hard to know if you’re making a difference, but it’s something.

thedougd2• 2 years ago

I would imagine it would destroy the plastic. A common problem with retrofitting stardard split systems. They require a UV resistant drain pans.

Fire-Dragon-DoL• 2 years ago

This would he huge. Aside from the huge benefit, it would be great not having runny nose or cough 6 months of the year.

elric7• 2 years ago

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?

turtlebits2• 2 years ago

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)

elric7• 2 years ago

Why does it run on demand? Mine runs 24/7, though it ramps down to lower speeds at night or when I'm away.

dzhiurgis6• 2 years ago

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!

amluto8• 2 years ago

That Zehnder unit is fantastic. The filter, not so much. (“ISO Fine” is IMO particularly embarrassing. It should say something more like “ISO ePM 1 40%”, and then buyers would think “40%? that’s lousy!”). Even the fancier ComfoWell filter is crap. And they’re overpriced, have lots of resistance, and don’t last long. You can confirm how poorly it works with a portable particle counter.

Get something like this if you have space:

https://www.hvacquick.com/products/residential/Air-Filters/P...

And consider putting it upstream of the Zehnder unit in the outdoor intake duct. Then it will extend your ISO Fine filter’s lifetime to effectively infinity. Or you could replace it with ISO Coarse. Or with nothing :)

elric7• 2 years ago

I did consider filter addons, but sadly my house is too small, fitting the unit was already a pretty big challenge.

tgsovlerkhgsel2• 2 years ago

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.

mdp20218• 2 years ago

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.

pjc506• 2 years ago

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.

JoshTriplett4• 2 years ago

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?

mdp20218• 2 years ago

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.)

maxerickson2• 2 years ago

Lots of places are going to do the regulatory minimum for ventilation, and I sure haven't seen any much change to regulations.

schiffern5• 2 years ago

  >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...

euroderf2• 2 years ago

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"?

AtlasBarfed• 2 years ago

The medical establishment for years told everyone that viruses were spread by contact and not by air.

dzhiurgis6• 2 years ago

Hand washing mania throughout the respiratory virus pandemic was comical tho.

throw7• 2 years ago

Indoor air environments are usually poor. Just having outside air from open windows would be an improvement.

dzhiurgis6• 2 years ago

Which easily excludes 80%+ of the places either due cold, heat or pollution.

ClumsyPilot6• 2 years ago

Proper ventilation systems address that issue

coding123• 2 years ago

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• 2 years ago

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• 2 years ago

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• 2 years ago

A 20” box fan and 4 20” furnace filters

Rebelgecko2• 2 years ago

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

bjoli• 2 years ago

4x merv 13 filters.

A fan.

Now you have yourself a high performing air purifier.

ceejayoz• 2 years ago

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

alliao3• 2 years ago

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

ClumsyPilot6• 2 years ago

Basically all filters work l, they just need to be big enough. The largest air purifier from Xiaomi is okay, ones from ikea are a little small but nicely made

evilmusic• 2 years ago

Some good tips here https://youtu.be/nE3u-2EyW-s

retrochameleon• 2 years ago

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.

schiffern5• 2 years ago

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).

jimberlage2• 2 years ago

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.

analog313• 2 years ago

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• 2 years ago

What do you think about vaccines?

4fterd4rk• 2 years ago

There is zero proof that this is the case.

alliao3• 2 years ago

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

patrickhogan1• 2 years ago

Now if they would just open the windows :)

rajnathani• 2 years ago

Given that air purifiers could increase airborne endotoxin levels [0], that instead better ventilation should be prioritized as it also solves the higher CO2 problem, where we know cognitive function slows down due to higher CO2 levels [1]. Given that OSHA sets an upper limit on CO2 in the workplace, I wonder whether daycare centers have such norms enforced too.

[0] https://www.sciencedirect.com/science/article/pii/S016041202...

[1] https://www.ucl.ac.uk/bartlett/energy/news/2018/dec/study-mi...

DrNosferatu2• 2 years ago

What kind of purifiers did they use?

(couldn’t find in the posted article)

optymizer• 2 years ago

This 󠁗󠁥is 󠀠󠁤silly. 󠁯󠀠We 󠁩󠁴can 󠀠󠁦encode 󠁯󠁲data 󠀠󠁴in 󠁨󠁥plaintext. 󠀠󠁬What 󠁵󠁬then?

(this 󠁺󠀮message contains a hidden secret)

eleveriven5• 2 years ago

Improving indoor air quality could be a simple yet impactful measure to promote health and reduce the spread of infections

Study: Air purifier use at daycare centres cut kids' sick days by a third (2023)

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