An air purifier is the best noise machine for me, much better than the white noise machines with the tinny speakers. Even the brown noise setting on those isn't nearly deep enough to let me sleep.

What are people's target AQIs? I have indoor monitors in our high-rise building in SF and live 100 m from the freeway and we have:

    PM2.5: 2.6 µg/m³
    PM10: 0.5 µg/m³
    VOC index: ~97
    CO₂: ~505 ppm

That's the baseline. When we're cooking, like now, it's:

    PM2.5: 10.8 µg/m³ (AQI ~46)
    PM10: 17.5 µg/m³
    VOC index: 122
    CO₂: 572 ppm

None of those seem particularly concerning. We have a gas range, and 15 min past the end of cooking everything is fine. I must imagine that most people don't live right next to the freeway so they probably have even better air quality except during wildfire season.

An air purifier is a good addition to a kids bedroom.

I got one during Santa Cruz wildfires in 2020 and now the kids have a pavlovian reflex to sleep once that gets turned on.

Ikea makes an air-purifier table, which is a end-run around it being a useless box in the room when switched off.

It's fairly expensive, not as good as a purpose built one, but it blends into the average room pretty well.

Yeah we do this at home. Bedrooms plus the great room on the kitchen side.

It might not be guaranteed to help, but it sure doesn't hurt since it's cleaning the air anyway.

I have 4 Coway and 2 Winix purifiers and I can confirm: they're great sleep noise generators! The plastic front pieces and the filters themselves block/baffle any high frequency noise from the fans, leaving you with a pleasant low/mid frequency whooooooosh. I like it better than the sound from small cheap solid state machines; their small speakers can't do low frequencies.

    For most circumstances where someone would use 
    a white noise machine, this kind of small purifier 
    is all-around better. 

Hmm. The word "most" is doing a lot of work here.

Depends if you enjoy fresh air when you sleep or not. If you've ever monitored CO2 levels you know how quickly they climb in a closed room.

But, if you are blowing fresh air into a room, or have the windows open, the filtration effectiveness of these units approaches zero pretty rapidly. And these air purifiers aren't exactly free to run: they use ~50-100W of power and if you run them 24/7 you can expect to spend $100+ per year on filters.

So there's no perfect answer...

I bought a large soldering iron air purifier and it turns out to be great; it has a continuious speed selector, easy to replace filters, and very pleasant spectrum. I like it better than the air conditioner, which cycles on and off noisily.

I’m always wondering what kind of constant noise might damage someone’s hearing (maybe develop tinnitus or long term hearing loss etc)? Is it only the volume or also duration and frequencies etc? Is there a risk having a noisy air purifier on all night?

This makes me wonder, for a truly travel-size solution (or just otherwise compact needs), if there's a viable alternative that directs filtered air at a sleeper's head? In other words, would the net effect be equivalent for one person (such that they're breathing more or less the same cleanness of air)?

I grasp that such an approach might draw unfiltered surrounding air along with the filtered stream of air, and imagine that it would likely be easily overwhelmed by a steady supply of exceptionally polluted air (wildfire smoke or simply a heavily polluted urban area), but I still would be interested in knowing if the compromise never overcomes a level of placebo effect, or if there's a point where it actually achieves measurable benefit (both in efficacy and portability—like a even more compact and directional version of the Corsi-Rosenthal computer fan solution.)

Alrighty, don't a lot of people already do this? Sometimes I'll do both an air purifier white noise and some music or something from myNoise

The Austin Air HealthMate is great as a noise machine. Very loud. It’s a HEPA filter and lasts 5 years. Never seen any other that lasts that long, but you pay for it upfront. after-market replacements are $250-300 for another 5 years.

Ive been relying on an air purifier or desk fan as white noise for years but recently switched to airpods 5 anc which has pretty much replaced the former

I run a Midea dehumidifier around the clock during the summer. The inverter driven compressor noise is quite pleasant. It masks higher pitch tinnitus very well.

Air purifier is gonna use a lot more energy than just a small speaker. The energy cost swamps everything long term

You can use them as random number generators, to replace your lava lamp for example.

Does that mean your air doesn't get filtered if you stop or decide to turn down the white noise?

I prefer having quiet air filters that I can run all day (based on air quality) instead of noisy ones I only use at night.

I use my philips as noise machine :P But like year ago it changed noise and I don't like it that much anymore

True, mine does that job really well too. Not too much high in it either, just a nice low rumble.

For sleeping I prefer rain sounds though

I prefer pink noise.

For me, that's another reason not to have one.

I like silence.

I consider noise from things like a refrigerator, or a computer case fan, to be distracting, and a reduction in the quality of my environment.

White noise is still noise, and there's no noise like no noise...

I've been doing this for literally decades. Now when I go to someone else's home without an air purifier it feels painfully quiet AND I can almost feel the stale air. I much prefer it even if it's just some minor placebo effect.

Glad to see I'm not the only person who does this

I've considered an air purifier for allergy reasons, but...

>removes smoke and infectious particles

Where do people live that they need to remove such things, 18th century London?