Comment by stared | Hacker News Reader

Comment by stared | Hacker News Reader

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When it comes to ultrasonic humidifiers, they do generate a lot of PM 2.5, see:

https://blog.getawair.com/awair-investigates-how-your-humidi...

It is NOT certain that these particles are as bad as ones from dust or combustion. All in all, when small droplets evaporate, what remains is water-soluble salts, rather than anything more reactive or harder to remove, see https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3922954/ as mentioned in https://learn.kaiterra.com/en/air-academy/humidifiers-cause-...:

"In a study on mice, researchers discovered that inhaling the dust from ultrasonic purifiers produces a cellular response, but this response lacks the inflammation and damage associated with other forms of particulate matter."

Myself, I got shocked when my air purifier suddenly started showing a huge amount of pollution (and yes, my eyes turned red). Only afterwards, I checked it was exactly because of my freshly-bought ultrasonic air purifier. Now I have an evaporative one - not as fast, not as spectacular, but better.

That's why you gotta use them with reverse osmosis filtered water. And not one that remineralizes, you can do that later on your own. I have a ultrasonic humidifier, reverse osmosis water filter and air quality sensor, it's all good.

I use distilled water

is there a downside to just using an evaporative humidifier?

The power draw at the humidifier will be larger, but the net power cost is about the same assuming a constant indoor air temperature. I always use filtered water for the US humidifier, but I'm reconsidering it now.

I literally just have some planting trays with a half-inch of gravel that I pour water into every couple of days.

Works wonders, is cheap, and easy to clean. Evaporation happens for free if you let it.

Maybe works for one small location, but that doesn't put nearly enough water in the air for common humidifier use cases of a gallon a day or more.

This seems crazy to me. I have to dehumidify my home to keep it at 35%. Humidity is a constant battle. I couldn’t imagine paying to dump water in my air and promote mold.

The recommended humidity level is 40-60%.

Dry mucus membranes makes you more susceptible to a number of respiratory problems. If you have mold, everyone does to some extent, drying it out will just make the health problems worse as it aerosolizes the mold. Mold aside, for optimal health a level between 40-60% is advised. Allergy sufferers are especially sensitive to this.

This is very climate dependent. New Orleans or Miami will have much more natural humidity than Boulder or even Boston in the winter.

Ultrasonic one is my first, only started paying attention to all this stuff because of 2020 and went all in, just trying to make my home a less crummy place.

Watch this https://www.youtube.com/watch?v=oHeehYYgl28

Optional follow-ups:

https://www.youtube.com/watch?v=TC9-t47tKts

https://www.youtube.com/watch?v=HfFAiCMLJ14

They have mold/bacterial growth problems (and use more electricity).

But both types have easy solutions to their respective problems:

- Use distilled water in the ultrasonic.

- Regularly clean/replace wick in your evaporative (or use a water stabilization agent).

Even the article at the top says they measured "0" particles when distilled water was used.

Until reading this thread I thought using distilled water in them was common knowledge. I believe that is what the manual with mine even said.

I’m curious whether you’d get the same effect from living/working near a waterfall / other natural source of vaporized water droplets.

Do the hospitality staff at Niagara Falls get sick more often than other people in hospitality?

Are these humidifier particles bad at all? What does “cellular response” mean? Typically combustion particles are bad because they contain carcinogens and PM2.5 can deposit deep in the lungs.

This seems like a “PM2.5 bad no matter the source” theory which isn’t supported at all.

> Are these humidifier particles bad at all?

It's limescale, you don't want it in you lungs. Kidney stones also have some relation to it, probably not exactly caused by hard water, but they get their building material from somewhere.

Technology Connections did a video on humidifiers, and if I remember correctly the evaporative ones weren't actually slower than the ultrasonic ones: https://www.youtube.com/watch?v=oHeehYYgl28&ab_channel=Techn...

this page from the same site as the OP has links to more studies: https://dynomight.net/humidifiers/

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