12/12/2025 at 11:37:05 PM
On a tangent note: don’t use ultrasonic humidifiers. Unless distilled water is used, they create a shit-ton of pm2.5 particles.Use evaporative humidifiers (just disks with myriads of small notches for water to cling on and a fan): https://us.smartmiglobal.com/pages/smartmi-evaporative-humid...
by piskov
12/13/2025 at 4:58:03 AM
> On a tangent note: don’t use ultrasonic humidifiers. Unless distilled water is used, they create a shit-ton of pm2.5 particles.Not according to my uHoo air quality monitor. I have had one running a few feet from the monitor for over a week and there hasn't been any notable increase in PM2.5 particles.
by wnevets
12/13/2025 at 3:26:16 PM
Last time I checked (brought my sensor to the office to one room with ultrasonic) it showed 101/105 ug/m3 for pm2.5/pm10In the next room (where there were none) it was 6.
Depends on the water, I guess.
by piskov
12/13/2025 at 5:21:14 PM
How large is the space with the humidifier? My space is wide open and that might be the biggest reason for my lack of increased PM2.5 readings.by wnevets
12/13/2025 at 7:33:18 PM
I think the parent poster is correct that it depends on the water.I have a couple ultrasonic humidifiers, if tap water is put in them it immediately sends the AQI on my air quality monitor into the "Dangerous" level. I have the monitor upstairs and it detected it when my girlfriend put tap water in the humidifier downstairs.
Purified or distilled water works fine. I bought a counter top water distiller because it was a pain lugging 15 gallons of water into the house every week all winter. You can see the residue of whatever was in the tap water at the bottom of the distiller after it runs and it doesn't look like anything I would want to be breathing.
by klatchex_too
12/13/2025 at 5:51:35 AM
> any notable increase in PM2.5 particlesWhat's your PM2.5 baseline, and did you measure TDS in the water?
by Elucalidavah
12/13/2025 at 6:07:49 AM
Since Nov it's been fluctuating between 5-7 ug/mg, with a few spikes hitting 9 and 10. At this moment its a 6.I haven't checked the TDS but when I used a water test strip for an aquarium early this year it was in the hard water range.
by wnevets
12/13/2025 at 3:30:27 PM
Thanks to this post, I checked my ultrasonic filled with tap water. With it running all night in a bedroom with an open door, morning pm2.5 readings are ~30 and the meter is in the kitchen.by wintermutestwin
12/13/2025 at 8:12:04 PM
The ones I had for a bit basically fogged out the apartment immediately and left white (i’m guessing salt) deposits all over everything. I know you are supposed to use distilled but it’s cost prohibitive at the rate these blow through water unless you also have a home distillery.by kjkjadksj
12/13/2025 at 1:07:47 AM
> Use evaporative humidifiersYou don't have to buy one either. A suspended wet towel with a fan blowing on it will work very well. If you want to get fancy, have the last inch or two of the towel sitting in a tray of water.
by esaym
12/13/2025 at 1:27:10 AM
But then I have to buy the towel and the fan, the tray, something to suspend the towel at the right height …by loloquwowndueo
12/13/2025 at 2:52:53 AM
This is cheaper, and the towel and fan can be repurposed. Just buy a 3D printer for making the the suspension part (/jest)by dependency_2x
12/13/2025 at 5:42:41 PM
My brother's house in Perth, Australia has an antique air conditioning system in the roof space that works in exactly this principle. 4 blankets that wick up water and have air drawn through them and into the house by a fan. It's in disuse now but I understand they were common and quite effective in the day.by abraae
12/13/2025 at 2:00:57 PM
That's a permanent bachelor design aesthetic.by jgalt212
12/13/2025 at 3:57:21 PM
Turns out young me was on to something, I wasn't just leaving wet towels laying around, I was fixing the air humidity problem.by Etheryte
12/14/2025 at 12:59:10 AM
I’m not sure that has a performance of 0.3L per hour (needed when it’s real cold outside).But any thing beats nothing, I guess. Kudos to you
by piskov
12/13/2025 at 7:30:04 PM
Don't use evaporative humidifiers(the motorized wet towel). I don't know if it actually cause legionellosis, but it's not very sanitary, and the sanitizing additives for those are known to be actually harmful.Use boiling type humidifiers (basically just electric tea kettles).
by numpad0
12/13/2025 at 11:17:36 PM
Water evaporates alomost completely and is changed daily (I rinse both container and disks in the tub with high-pressure mode from showerhead), so I don’t think any contamination is likely.Been doing this for years.
by piskov
12/12/2025 at 11:52:33 PM
Alec from Technology Connections also has a great video comparing humidifiers hereby jborichevskiy
12/13/2025 at 2:05:14 PM
Are pm2.5 particles a problem if they are water soluble? After entering the body they will just dissolve.by marcinpieczka
12/14/2025 at 9:34:42 AM
Hard water often contains hard to dissolve minerals. An evaporative humidifier over the time accumulates limescale and it’s very difficult to remove it, you cannot just dissolve it. With ultrasound humidifier all this limescale will be in the air. Admittedly not in all regions the water is hard but if it is then ultrasound humidifier will be a bad choice.by citrin_ru
12/13/2025 at 11:08:50 PM
Depends whether you want that stuff in kidneys and what have you.Bigger particles are known to irritate the lungs and even cause asthma (google or ask gpt)
by piskov
12/13/2025 at 1:06:04 AM
Distilled water isn’t strictly necessary. I use mine with purified water with a reverse osmosis purifier. I periodically test the TDS of the water to confirm it is low. It’s fine.by kccqzy
12/13/2025 at 3:28:51 PM
I’ve run dyson ultrasonic humidifiers for a few years. The whole appartment was in white dust.Especially evident on some black leather bags in the wardrobe.
by piskov
12/13/2025 at 10:06:40 PM
You can buy a cheap tester for TDS (total dissolved solids) for <$20. Test the water before pouring it into any ultrasonic humidifier.by kccqzy
12/13/2025 at 11:10:26 PM
I just switched to evaporative ones like smartmi I’ve mentioned.by piskov
12/13/2025 at 1:27:29 AM
The best solution I've found a few years ago is one Venta LW 45 for every 30 m² of space. That's enough to run them on the lowest speed while maintaining acceptable humidity and CO₂ levels.Higher speeds are too noisy. Smaller machines evaporate less.
For sub-zero outside temperatures, it's necessary to add at least 5 g of water to each cubic metre of air coming from outside.
The recommended ventilation rate of 30 m³/h per person requires to evaporate 4 liters of water per day.
by nvch
12/13/2025 at 2:53:37 PM
That’s a lot of refilling. You might want to look into a whole house humidifier, I added an aprilaire 700 evaporative to my hvac ducts, it costs a few hundred $. Plumbed in, automatic. So much less screwing aroundby dalyons
12/13/2025 at 3:33:23 PM
What sort of maintenance do you have to do on it?by gessha
12/13/2025 at 9:36:19 PM
Once a season / 6 mo of running you replace the evaporator panel, which is ~$50 for branded or $10 for amazon copies.by dalyons
12/14/2025 at 12:50:47 AM
Chinese I’ve mentioned blew Ventra out of the water. I’ve been using humidifiers for the last 15 years and switched to smartme around 5 or something like that (liked the idea of auto speed and was tired of aged squickness after many years of its predecessor).Haven’t used the first generation. Had a couple of the second (they notoriously had water level sensor issue that could be fixed just enabling “drying mode” that always ran for 8h after the sensor thought there were no water).
Third gen is the charm.
Cheap, effective (pump, double-bottom for rounded instead of flat tank — uses evry last drop), quiter, 5L tank, less creak after a few years.
tldr; I only wish it lasted whole 24 hours when it is -5C and lower outside, but I guess that requires 7-8L.
Also, having a few helps with the noise (I have total of three in my apartment).
by piskov
12/13/2025 at 1:55:34 AM
Which venta are you referencing here?by noitpmeder
12/13/2025 at 2:02:58 AM
They are referencing https://www.venta-air.com/en_us/product/lw45-original-humidi...I also have one and love how easy it is to clean.
by mercnet
12/13/2025 at 3:11:40 AM
For $500 it better clean itselfby SauntSolaire
12/13/2025 at 7:30:48 AM
I bought two Ventas well over a decade ago, and they still work as well as the day I bought them. They're an expensive initial investment, but IMO worth it over the long run.They are also mechanically simple, so I trust that if they ever break, I will be able to repair them.
by InsideOutSanta
12/13/2025 at 12:03:39 AM
That Smartmi model seems to have toxic IoT in it.I'm currently using the Vornado EV100 non-IoT evaporative humidifier, and my only complaints are relatively minor, as humidifiers go (consumable wick, fan noise, insanely bright blue LEDs). https://www.vornado.com/shop/humidifiers/evaporative/ev100-e...
by neilv
12/13/2025 at 12:22:13 AM
You don’t need to connect it — works completely offline.Also no consumable parts there: just plastic disks which you clean with couple of spoons of citric acid dissolved in water from time to time.
by piskov
12/13/2025 at 1:02:36 AM
Couldn't you just use vinegar?by NewJazz
12/13/2025 at 4:51:00 AM
I found this too. I wonder why they don't just accept a PUR water filter on the input side.I also wonder why mini-split heating systems drip and pool water outdoors instead of pumping that distilled water back indoors for humidification.
by dheera
12/13/2025 at 5:58:06 AM
It's funny in an ironic way because the original purpose of air conditioners was to remove humidity from the air, the mechanism used was to cool the air down thus forcing some of the moisture out. The general public quickly caught on that having cool air was nice in it's own right and that is the main purpose these days. however the dehumidifying function is still sometimes used, people are surprised when their air conditioner turns on at the same time as the heater (why are they fighting each other?) but that is because the system is trying to remove moisture from the air before it is heated. Mainly seen in cars so the windows don't fog up.Probably something wrong with me but I just find it humorous trying to add moisture to a system designed to remove it. Really a reasonable request however, depending on where you live the air can get quite dry.
by somat
12/13/2025 at 1:19:19 PM
You’d need a reverse osmosis system, not just he charcoal filters like thatAnd the condensate water from an AC evaporator coil is not anything like distilled water, dust/bacteria are also in it.
by throwawaysoxjje
12/13/2025 at 10:06:27 AM
> I also wonder why mini-split heating systems drip and pool water outdoors instead of pumping that distilled water back indoors for humidification.Do you want Legionnaire's Disease? Because that's how you get Legionnaire's Disease.
https://en.wikipedia.org/wiki/1976_Philadelphia_Legionnaires...
by ErroneousBosh
12/13/2025 at 12:35:19 PM
During summer dehumidification is needed in most areas.And it is really not distilled water. It gathers dust and so on from air. Distilling in more so closed circuit, where as those are very much open.
by Ekaros
12/13/2025 at 1:54:58 AM
This is pretty crappy one-size-fits-all advice in itself.If you’re willing to use distilled water, ultrasonic humidifiers have their own advantages over evaporative.
I’m personally willing to buy distilled water. It’s a dollar per gallon, and we only need the humidifier during a short few months. You can even buy a small countertop water distiller for under $60.
by dangus
12/13/2025 at 2:37:34 AM
I'm thoroughly unconvinced.Doing some basic research... hard water is overwhelmingly various carbonate and bicarbonates of magnesium, calcium, sulfur, iron, maganese, and aluminum. All of which are essential nutrients and readily soluable in water.
The other proposed problem was pathogen aerosols- however I was unable to access anything but an abstract. So, I don't know if they survived being aerosolized, produced more and/or worse pathogen count than evaporative humidifiers, Nor the size of the pathogens.
It seems to me the known risk is mostly mechanical (Asthma, exacerbated COPD, etc) and nonpersistent (particles dissolve and are used or excreted via the same pathways as when consumed). With an unknown risk on the pathogen side.
by butvacuum
12/13/2025 at 2:43:07 AM
> If you’re willing to use distilled water, ultrasonic humidifiers have their own advantages over evaporative.Unless you are anally retentive about cleaning it, ultrasonic humidifiers vaporize microbes into the air. There have been loads of studies about this.
The only real way to avoid this is to use the humidifiers that are boiling the water.
by bsder
12/13/2025 at 8:29:35 PM
The real pro tip is to get a whole home humidifier. They aren’t even that expensive. But I haven’t taken the plunge yet.They avoid all these issues and require way less maintenance than any other solution.
by dangus
12/14/2025 at 1:15:28 AM
Can’t do that in the city :-)by piskov
12/14/2025 at 4:43:36 PM
I've seen multi-unit condos with the ability to modify your own HVAC, but I get where you're coming from.by dangus
12/13/2025 at 1:38:24 AM
How did we survive the last 3.5 billion years?by mytailorisrich
12/13/2025 at 1:50:58 AM
We didn't have access to modern technology... like ultrasonic speakers?Also we died at a young age. Everyone dying at 40 isn't incompatible with the species surviving but it's what advice like that is usually trying to avoid (and even less extreme outcomes).
by gpm
12/13/2025 at 2:05:42 AM
The concept of everyone dying at 40 is a myth/misunderstanding anyways - the reality was a lot more bimodal than that.by SauntSolaire
12/13/2025 at 2:19:21 AM
Eh, here it's more of a simplification than a myth as used in my comment. There are two effects:1. We've reduced infant (and childhood) mortality. My comment isn't talking about this effect but it did drag down average life expectancy substantially. Including this effect life expectancy at birth in the stone age might have been as low as 20... but as you say the bimodality means this is a deceptive statistic when used this way.
2. We've made it so you on average live longer even if you survive childhood, my comment is really just about this part of the effect. It's still a simplification because saying "on average if you survive childhood you die at 40" isn't the same as "everyone dies at 40" but closer to "adults die at all ages in a reasonable smooth monotonic curve and 40 is about the average age they live to but some get lucky and live to 80 or whatever". But then "don't use ultrasonic dehumidifiers" is like this too, using one won't kill you at some specific age, it will just slightly increase your chance of death every year for the rest of your life however long that ends up being.
The number 40 was picked out of a hat, too. It should be right for some areas at some times just by coincidence though and since I was non-specific that makes me right ;)
by gpm
12/13/2025 at 12:25:29 PM
The age 40 includes childhood mortality! It's difficult to get records from prehistoric humans for obvious reasons, but as early as Ancient Greece you had the upper class living about as long as we do now a days. A study of men of the time found the average life expectancy to be 71.3 years. [1]And while the Bible includes plentiful mythological components, it also includes many historical and contemporary accounts. And this verse is certainly of the latter: "The length of our days is generally seventy years, or eighty years if one is strong, yet even the best of these years are filled with toil and sorrow, for they pass quickly and we fly away." That is part of the Old Testament (Psalms 90:10) that is believed to have been written somewhere from 1400-1200BC.
If you want more contemporary stuff that's completely indisputable you can also take random selections of people of renown. For instance the main Founding Fathers are a great example because they all were relatively young when their names become inexorably etched into history, yet their final life expectancy is again well into the 70s. The youngest major founding father to die was Hamilton, in a duel - at 49. Then Hancock died at 56 - likely of gout which can be caused by things like excessive indulgence. Next up was Washington who died at 67, probably more of the cure than the disease - he was leeched to the point of being pale as a ghost on his death bed. Jefferson, Franklin, Madison, Sam Adams, John Jay all lived to their 80s. John Adams made it to his 90s.
---
I am not trying to claim these samples are representative. These were wealthy individuals who would be relatively immune to famine, war, and other such factors that could have a catastrophic effect on lower classes. But when speaking of life expectancy, I think we are implicitly asking the question 'how long could somebody reasonably expect to live xxxx years ago without access to modern medicine and technology.' And that's what this sampling of people answers.
by somenameforme
12/13/2025 at 5:05:16 PM
> The length of our days is generally seventy years, or eighty years if one is strongWhich translation is that? Or are you paraphrasing?
Most translations don't include "generally," and therefore read more as an upper bound "if one is strong" than an average.
by Cpoll
12/13/2025 at 5:53:05 PM
Just a poor memory translation. Yeah, generally is incorrect - though I think the correct phrasing also implies an average age of natural death, rather than an upper bound. There were certainly plenty of people living past 80. In the aforementioned study of Ancient Greeks, there were at least 3 centurions - Aristarchos, Democritos, and Gorgias. Granted 1400BC is a thousand years yet prior to that already ancient time, but life peaks seem to be relatively unmoving for humans, and so I don't see any major reason to think there would have been a major difference between 400BC and 1400BC.by somenameforme
12/13/2025 at 10:10:51 AM
So up until about two or three years ago when everyone suddenly became terrified of "particulates", people died at 40?The Victorians called, they want their Night Air Panic back.
by ErroneousBosh
12/13/2025 at 5:08:12 AM
Quite poorly in factby wpm
12/13/2025 at 1:42:11 AM
A lot of us didn'tby HappyJoy
12/13/2025 at 1:52:45 AM
Glad to know that's solved nowby SauntSolaire
12/13/2025 at 8:07:59 PM
Drying clothes indoors is also effective. When I set up my laundry rack rh can surge by 30%. I imagine setting up a tray of water under a ceiling fan might be similarly effective.by kjkjadksj