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The bigger the fan the better, IMO. I really love those cheap square box fans... It's hard to beat that deep, low hum that small speakers and small fans just can't replicate.

Totally agree. I've never liked the speaker generators. The old school DOHM models are way better because they do not use a speaker, they have a fan inside.

You can easily send white noise to good speakers, if you have any. There are free apps for it, not to mention hours-long YouTube videos with white/pink/brown noise.

Yea, having it and using it at max just as I go to bed just makes me feel much better for the air I'll be breathing while sleeping. I also used to always fall asleep to some noise or music, so this is such a nice replacement

CO2 - I'm thrilled with anything less than 800 ppm (half justified by being the lowest number I've ever seen a study suggest might have health effects, half justified by being at a point where I personally don't notice that I'm more drowsy).

PM2.5 - My impression is the health risks here are more cumulative exposure (and include things I'd like to go without in my life, like alzheimers) and a pretty straight line of "lower is better all the way to zero". The WHO's guideline is mean exposure of 5 µg/m³ so I guess I'd adopt that if I had to put a number on it. (But it's a mean, I wouldn't worry about briefly exceeding it)

PM10 - No real opinion (I'd rather worry about PM2.5)

VOC index - I'm not sure this is a standardized thing, but the version I've come across is an index relative to the average that particular sensor has seen in the last 24 hours. So there's no standard possible here.

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As for a gas range I would worry about NOX considering the studies with them causing and aggravating asthma. That said your CO2 levels are low so I suspect you might have sufficient ventilation that this isn't a huge issue for you (especially if that ventilation is in the form of a fume hood over your stove that you actually use).

VOC index means literally nothing. (I've read the datasheet, implemented some kludges to log raw data, and contemplated the formulas. The data is high-pass filtered. You literally cannot conclude anything about a single measurement if you assume the sensor is somehow magically perfect. You might conclude that there is more VOC (or less -- not all VOCs have the same sign in their effect) when cooking than when not cooking.)

I target 0 PM2.5, but this only necessarily makes sense as a target if you have the ability to filter your home's supply air. And a good vent hood should be able to avoid any detectable bump while cooking (although a vent hood without filtered makeup air may cause a bump due to increased infiltration of exterior air).

There's either a typo or something wrong with your sensor: you can't have pm10 < pm2.5.

(Equivalent to saying you have more people under 2.5 years old than under 10 years old.)

We have higher numbers than those and live fairly far from any freeway. Maybe your high-rise is doing better than you think.

Depending on the month, my kitchen AQI averages between 1-4, representing PM2.5 values of 0.1 - 0.8 ug/m^3. Bedrooms are likely better as they don't have the gas stove.

CO2 while occupied is generally under 750; I'd prefer to keep it under 700 but we also balance that with energy efficiency for that make-up air; I don't have an ERV, so we suffer a little there.

(We don't live by a freeway but - (a) Pittsburgh's air isn't great; and (b) the canadian wildfires were pretty bad here at times this summer, and that was what caused that 0.8 ug/m^3 pm2.5 spike).

We have, um, a lot of air filters left over from covid, though, so we're a little spoiled in terms of being able to manage AQI easily.

They work great, better than a fan because it clears the air.

I have one blowing gently across my face while I sleep. It cools me down, and blocks out the highway noise.

> ~50-100W of power

That sounds too high? An AirFanta 3Pro on "2" is 141 CFM at under 5W https://www.jefftk.com/p/running-an-air-purifier-on-batterie...

That’s the design appeal of ionizers like BlueAir (not most ionizers, but specially those designed to supposedly prevent ozone production). They comparatively sip power while getting the same measured reduction in particulates and ozone.

One of the best air purifiers you can get (linked in the above writeup) uses PC fans and a custom controller where you can control the speed/volume: https://housefresh.com/best-air-purifiers-we-tested/#2-best-...

Health and safety regulations are all about noise levels and exposure duration, not frequencies

Wonder no more. There is mountains of research on this for occupational health concerns. As long as your fan is <70dB there is virtually no risk to your hearing.

There might be some to your dog, on the other hand. Anecdotal, but my dog went deaf pretty early and he sleeps in a room where I run an air purifier all night. Not sure if there is correlation or causation there but that's my little anecdata.

There's an Airfanta 4Lite which uses laminar flow to achieve that:

https://air-fanta.com/products/airfanta-4lite

However, testing seems to show that the clean air flow is neither wide nor far; it would only be effective right next to your face and you can't really move:

https://www.reddit.com/r/Masks4All/comments/1di1n4t/can_a_po...

There aren't a lot of use cases for it.

I have seen models designed this way! Vornado used to make one, I think it's discontinued.

These directed-air "personal models" make a lot of sense to me... at least in theory. I haven't seen them properly tested.

The big air purifiers work great.. if the room is closed up. But their effectiveness approaches zero if you have the windows open or otherwise have unfiltered air entering the room. Which is kind of important, if you don't enjoy breathing in sky high levels of CO2. (If one's allergies are bad enough, or a wildfire is raging outside, CO2 might of course be preferable to particulates)

They are truly excellent machines. I’ve used a couple of these over the years, never had an issue.

I have that machine. It seems better at filtering chemicals and VOCs but not great at filtering particulates. It gets rid of odors very well but my PM2.5 meter barely budges.

If you want the better sound but don't care about the purifier, then get a DOHM sound machine. It uses a fan and sound great, and I'd guess the energy consumption is pretty trivial.

this feels like a 'dose makes the poison' scenario. you're talking about maybe $10 of difference annually if both were run continuously. and that's only if you bought an inefficient air purifier - if you elected to use, for eg, four Arctic P14 PSTs in a CR box then that's maybe double the kWh. this ends up being a couple of bucks more annually for the added benefit of having better air quality

swamps everything except for the health benefits

I'll stick with RFC 1149.5.

If you turn it off, sure.

I have one in the bedroom. On low, I barely hear it during the day (extra ambient noise from outside) but at night the white-noise is subtle but effective. That said, I don't like "loud" white noise, just a quiet hum.

For air filtering, you want big fans that move relatively slowly. At least, at lower settings.

I still haven’t seen anything else that can compare to IQAir HyperHEPA filters. They use these things in hospitals.

Many air purifiers are silent on lower settings and louder on higher settings. If I want noise I turn mine up. If I want less noise I turn it down.

Agreed, possibly because it's spectrum distribution is a lot closer to natural sounds, like flowing water.

If you can tolerate the in-ear physical sensation, Etymotic makes some fantastic earplugs for reducing noise. I similarly found even small noises to be distracting, and I couldn’t avail myself of earplugs or noise cancelling headphones because they also felt distracting. The clever thing that Etymotic did is design to reduce noise evenly across the spectrum, so it feels like turning the world’s volume knob down, rather than unevenly suppressing certain frequencies. Noise seems qualitatively less distracting with “the volume turned down” in this way, and the uneven suppression turned out to be the part that bothered me about other options. I consider myself sound-sensitive yet these things made a 14-hour flight in the same row as a crying baby quite tolerable (to both mine and the suffering parents’ relief). Your mileage may of course vary but this was a big QoL upgrade for me and it may be for you too.

Agreed. I'd love to have air purification (and air circulation to reduce CO2) without noise, to the extent possible.

[delayed]

This is approximately what it looked like near my area in mid July for a few days.

https://commons.wikimedia.org/wiki/File:Wildfire_smoke_Wyand...

It just looks like fog, but it is smoke, and the sky has an unusual orange color. Smells and tastes like you are standing in the path of a campfire, but you can't move out of the way. It irritates your eyes and throat if you spend more than 20 mins out there. You can go inside, but if the building you are in is leaky, it will smell like smoke inside there too.

The actual fire was hundreds of miles away. You can try driving in any direction for hours and not be clear of the smoke. Still, compared to other areas, this is barely worth complaining about.

Anywhere in the US west of Texas and most of Canada.

Allergens are likely considered "infectious particles" for that particular sentence.

>Where do people live that they need to remove such things

SF Bay Area during the summer fires of a few years ago

I use mine just to purify air for my precious LTO tape drive. My baby doesnt like dust

Almost anywhere now in North America or Europe during the summer.

Most of the world, unfortunately. Just look at an air quality map.

As an allergy enjoyer there is no air too pure.

My allergies became generally better at all hours just from sleeping in super cleaned air.

Why? Reducing baseline inflammation perhapse? Maybe decreased inflammation during sleep helps too, improved breathing? idk. Whatever it is this organism seems to prefer it.

Even when exposed to allergens during the day the run up to sneezing is much slower or doesn't happen.