Just a question for anyone. I’ve been monitoring particulate with a PM2.5 AirGradient sensor, and when I added an ultrasonic humidifier to the room the readings went off the chart.
I’ve read that there could be two reasons, one the small water particles in the air are affecting the reading (which should be harmless) or second there are mineral and other impurities in the water that are now airborne which might be more harmful.
Any opinions?
Hello Mark, both theories are correct, the PMS5003 will measure water droplets from the humidifier as particles.
Secondly, ultrasonic humidifiers will liberate dissolved salts in tap water as airborne 2.5 micron particules.
These salts are primarily calcium carbonate and various sulfates. Studies have shown these particles aren’t necessarily harmful, but no long term studies have been done.
If it’s a worry of yours, I found replacing tap water with distilled water was effective in significantly reducing pm counts when working with an unfiltered atomizing mister. Using filtered water was only slightly effective.
Thanks for the info, I think we’re going to switch to using a steam based humidifier system which should not suspend dissolved solids in the air. I’m wondering if we’ll see an increase in pm2.5 based on just the humidity though.
You’ve just stumbled on the dirty secret of the humidifier business: there are facts taken together that suggest that ultrasonic humidifiers, which I’m guessing are the most popular, are likely the most hazardous to your health as used by most people. (Use with distilled water? No one with any serious need for humidification will do that, too cumbersome/expensive. By serious, I mean you monitor your humidity levels and aren’t say, just using it at night in a bedroom. You live in a dry area, or one that’s seasonally so - e.g. one with real winters & forced air heating).
A very balanced, well reasoned essay on this subject: The case against ultrasonic humidifiers. As the author puts it: maybe they’re ok, but why take the risk? I wish my evaporative humidifier was quieter, but for the most part I’m able to hear it as white noise (i.e. not obtrusive). Steam ones are out for me, they use too much electricity.
Don’t assume because they’re on the market and everyone has them, they can’t possibly be bad. Everyone used to smoke also…
I can also confirm this is a thing.
Boiling water, or ironing clothing for example will spike pm25 for a short while. It does however settle down reasonably quick.
We also had this phenomenon several years back in Beijing (super dry winter). our air purifiers went crazy after the ultrasonic humidifier was switched on. we since replaced all humidifiers with either steam based or cold evaporation machines. all work with tab water, however the more dirty your water is (e.g. in Beijing) the more often you have to clean the machines.
the other positive effect of cold evaporation compared to steam or ultrasonic is the fact, that you cannot make the room too humid, which can cause mildew and mold.
Highly recommend cold evaporation!
I ran into the same thing with tap water: my PM readings went off the charts – glad to know those salts aren’t likely harmful!
This article by a “competitor” steered me to distilled water.
In my case, with distilled water I saw zero PM2.5 from the humidifier.
