Where do you keep the air quality sensor?

I suspect that if you keep it away from the purifier, and closer to where you sit in the room, it's a more real representation of the air quality. Usually the air around the purifier would be purer than other parts of the room until an equilibrium has reached.

I haven't done extensive testing to validate this theory either, just a hunch. Let me know if my hunch is incorrect.

Right now the air quality sensor is in the basement, and the purifiers I'm comparing it to are upstairs. It's not a fair comparison, it just "seems" to be reporting using a different scale.

My plan is to put the sensor near one of my STARKVINDs and see how the numbers compare. This will tell me if they're measuring the same thing and reporting it at the same scale. Once I understand what the sensor is telling me a bit better, I'll put it in a more useful place. Your suggestion of putting it closer to where you sit is a very good one.

Humidity has a huge effect on the non-lab-grade sensors and that, combined with the fact that upstairs will have all the dander, fabric fibers, etc...of course they're different values.

The table version sounded interesting until I looked at the dimensions. 22" is way too low to be useful as anything besides a bedside table. Anywhere slse I'd describe it as more of a tripping hazard. That's lower than the seat height of a lot of chairs. A typical table is more like 30-32".

I’ve got two of the table version and find the heights to be fine. The one in my living room, used as an end table, seems to be slightly higher than my non-IKEA end table. It’s definitely not a table for doing “stuff” (working, eating, etc) at.

The other one is in my home office and serves mostly as a step to help the cats get to the window, the short height is a definite benefit here!

I’ve developed some mobility issues as I’ve gotten older. I’m tall enough/not overly long armed enough that 22” means I can’t pick stuff up off it without having to bend/stoop, which I can do but aren’t ideal. Actually just measures my bedside table and it’s 27” and just about right. 22” would absolutely be too low, putting it about 6 inches below the top of my mattress, which means I can’t see or reach the CPAP machine without basically getting half way out of bed.

This of course depends on how high your bed frame is, and how thick thick your mattress (and potentially box spring) are.

22” is pretty typical for an end table next to a sofa. For someone with a relatively low height bed it might make sense as a bedside table too.

It makes for a perfect bedside table though, the place where you'd actually want clean air the most. Virtually inaudible in the low speed modes.

This is to me one of the reasons for CPAP - you get filtered air all night long!

I do wish the filters were better though, they're really not very good, just basic cellulose. They're mainly to catch big stuff like pet hair. Nowhere near a HEPA.

That's a very fair point - I still find that they've made a difference for me, even with the limitations.

Yeah, I'm sure they do. I've got so many low-moderate level allergies that it's kinda hard to establish what normal even really feels like. I got a round of shots as a teen that helps, but it's still some level of congestion at the best of times. Actually the biggest difference I found when I first started on it (almost 10 years ago now), besides the obvious sleep stuff, is that the humidifier keeps me from getting nosebleeds about 3 times a week in the winter.

Unless you have a Phillips Respironics, in which case it helpfully adds bits of foam (pre-recall) or formaldehyde (post-recall) to your air stream. I realize that Phillips says it's under limits, but they aren't really trust inducing right now…

I have, unfortunately, found "low speed" mode on air purifiers to be not very effective at improving air quality.

Measured with an Airthings sensor, in my 1970s house, low-speed mode just clears temporary indoor-source pollutants marginally faster than having no air purifiers. In the case of exterior-source pollutants (i.e. wildfire smoke), low-speed mode is insufficient to keep PM2.5 in an acceptable range.

And this is with five air purifiers throughout the house that are sized for a significantly larger space.

This really depends on the rate at which air inside the house gets exchanged with air from the outside.

In my 2008 house, two air purifiers on low are sufficient to keep AQI at 0 and in the single digits during wildfires. They're rated for about 350 square feet each, while the house is about 1500 square feet.

Yes, completely true - if you had a home with positive pressure and a filtered HRV/ERV with sufficient volume, one wouldn't need internal air purifiers at all.

I've long wished for "smart" inwards-blowing window fans that took filters and conditionally only turned on when the air outside was an appropriate temperature - wouldn't be appropriate in all climates/seasons/times, but in my geography would pump clean air in into the house for months out of the year.

https://naturescoolingsolutions.com/ecobreeze-2-1-smart-wind... exists, but is pricey and isn't from a major-enough manufacturer to make me confident of after-sales support.

That’s a good height for a desk or dining table. Coffee tables, end tables, and side tables are commonly much lower. Very low coffee tables are less than one foot. Most of my living room is 15-17” for comparison.

> I really like this purifier's big brother, the IKEA STARKVIND, which is available in both regular[0] and table[1] versions.

I got one of these as well, and I recommend them with the extra carbon filter. Very, very nice thing to have in a kitchen, if you're a smoker or if you have cats. The carbon filter takes out a lot of nasty smells, enough to not smell anything food-y even in a directly adjacent room while running a frying pan and chopping onions, or when smoking a cigarette on the open window. And the "plain" filter picks up a loooot of the fur that you'd find everywhere including in your food when your cat decides it's time to go and shed everywhere she can.

How long do the carbon filters last in your experience? Does it have an indication of when you should?

The carbon filters in this machine are fairly sparsely filled and don't have a significant amount of carbon in them. Typically replacement is recommended after about 6 months or so, but I've found that with heavy use, similar filters last only a month or so before losing effectiveness. It has to do with how much odor and VOC is present in the area you are using the filter in, as well as how much it is running.

I made my own filters with over 2-3x the carbon by weight (bought from Amazon) in them, and they last about 2-3 months before they start emitting an odd smell (but they still seem to reduce odor, but they are no doubt trading new smells for older ones as they fill up).

I usually change the filters as soon as the smell becomes odd, in my case, the smell is like a slightly sour and damp version of the fresh and dry chocolatey smell that they sometimes have when new.

Hmm, that'll not work very well for my use-case then. I've not got a great nose, and I would like to keep smells at bay for visitors. Not planning on replacing a filter monthly "just in case" though.

Thanks for the info!

I don't have the link handy, but many/most of the inexpensive particle sensors are junk in one way or another. They're only good for relative measurements at best.

A recent air quality comparison demonstrated that there wild fluctuations across most brands. Nonetheless, I think it’s still helpful to see the changes in the environment, and to understand and observe how leaving a window open, or doing some activity, or handling some volatile substance, or how seasonal dust and pollen can affect hay fever in your own little microcosm.

Yeah I noticed that when I clean my washing basket with a little bit of alcohol the VOC jumps from 200 to 20000 in a matter of minutes and doesn't go back to normal for a day or so.

Even though I don't even smell it. These sensors are just incredibly sensitive.

Another example: burning one candle increases PM 2.5 considerably and after blowing it out the wick gives a little wisp of smoke that makes it peak from a normal 1 to 50 or so.

I almost entirely stopped using candles after getting an air purifier with a particle and VOC monitoring sensor (Electrolux/AEG Pure A9).

It's very enlightening. Even a single push of spray deodorant releases a crazy amount of particles and makes the purifier go crazy for a short while.

Is that short burst of deodorant actually harmful or do the numbers just go up a lot?

Alcohols are VOC's and many deodorants contain them. They are probably among the less harmful VOC's.

It measures the amount of particles in the air, it doesn't analyse their content.

Just having an ultrasonic humidifier in the bedroom makes the PM25 counter jump from 1-2 to 200-250.

An ultrasonic humidifier turns whatever impure water you feed in into tiny aerosols, from which most of the water quickly evaporates, leaving even smaller aerosols behind. Those likely consist of soluble salts (likely not terribly harmful) and bacteria (possibly quite harmful).

I would avoid using them unless, perhaps, I ran the output through a filter. Or I would use an evaporative humidifier instead.

From the same site as this air purifier article:

"The case against ultrasonic humidifiers."

https://dynomight.net/humidifiers/

This! Don't use an ultrasonic humidifier unless you fill it with distilled water. Tap water will just create a ton of white dust everywhere.

If you absolutely need more humidity in your home, get something like the Venta LW45 which has a half-submerged rotating disk and blows air over the still wet surface. Works with tap water (requires regular cleaning and a special additive).

I do not understand why IKEA makes it so hard to attach a FÖRNUFTIG purifier to a wall or under a table. I bought one to attach it under my son's room table, which fit perfectly, but putting four screw holes into the FÖRNUFTIG was a pain in the ass. It would make those things so much more versatile if scrwholew were already perpared.

I'm a bit confused by this comment. The assembly instructions[0] clearly show screw holes on the back of the unit and it appears to even include a template for putting the screw holes into the wall you're mounting it to. It doesn't look like the holes would be suitable for mounting under a table though, they'd probably prefer that you replace the table with a STARKVIND.

[0] https://www.ikea.com/ca/en/assembly_instructions/foernuftig-...

In terms of air quality sensors, what really made a difference for me was getting a CO2 sensor. "Fresh air" (low CO2) behaves way different than what j was taught. I live in a newly constructed building, which apparently is almost hermetically sealed. And we have no AC, since we're in Europe. As a result, air quality (in terms of co2) goes downhill unexpectedly FAST. And opening the windows for 5 to let in fresh air is definitely not enough to restore quality to sensible levels. EU norms say that public building should have less than 800ppm CO2, as anything above might affect cognitive abilities. However, reaching that level is almost impossible without constantly cracking the window (or an AC). I'd never have expected this....

This is one of the reasons why newer, "sealed" buildings need to be mechanically ventilated (ideally with a HRV or ERV to keep your HVAC waste to a minimum).

Most home AC systems in Europe don't provide fresh air, that's a common misconception.

That really sucks. Sounds like the ventilation system is poorly designed.

I wish that all modern buildings had properly sized FTX / air handling units. These exchange the old air with new air using the heat from the old to warm up the new air and at the same time can have HEPA filters for cleaning the air.

Some years ago I ran a department that did a lot of prototyping and research. One of the things we experimented with was CO2 sensors. Not hugely expensive sensors, but mostly cheap ones since we were mostly interested in relative changes (rather than absolute values) - and seeing what kind of performance you could get out of relatively inexpensive sensors[1].

(This is from memory)

We got a lot of interesting results placing sensors in a bunch of commercial buildings. Most rooms in all buildings we measured couldn't keep the CO2 levels below 1000ppm. In fact, most meeting rooms we measured would struggle to keep below 1200-1300ppm when in use and we regularly saw much worse numbers. In one building all meeting rooms we measured would quickly blow past 1200ppm when in use -- except the meeting room management used. Which tended to hover between 600ppm when not in use and about 800ppm when used (though it was big and rarely more than at 1/4 capacity). I guess that explains why complaints about low air quality fell on deaf ears.

We also discovered why the meeting rooms in the basement were so awful for late meetings. At around 1800 hours or so in the evening, the HVAC shuts down. From what I gather, in a tall building, there are supposed to be mechanisms to prevent air from moving back and CO2 dropping down the HVAC system and pooling in the basement. This one didn't. (In fact, ALL the buildings on the campus had the same problem since they were all built at the same time by the same company). So over a few hours CO2 levels would rise to a level where the sensors max out their range and get saturated. They would stay that way until a couple of hours after the HVAC got switched on in the morning.

People would sometimes use those meeting rooms until late in the evening.

If you use consumer air quality measurement devices, beware that they're not terribly good. CO2 sensors tend to have cross sensitivity to lots of other gases. And cheap (eg less than $400 for just the sensor component) particle sensors tend to be fairly crap.

A lot of sensors we found in HVAC systems are even lower quality than consumer grade stuff I've seen in products.

[1] The sensors we used are often found in premium consumer air quality measurement products. So they aren't dirt cheap, but they also aren't that great.

Seconded. A CO2 sensor is a gentle reminder to open the windows every now and then and get some fresh air in.

I own the Aranet4 sensor (highly recommend) and I’m in the US with not particularly great sealing and my sensor will read a 600ppm jump in a matter of 30 minutes.

I basically have to keep the window in my bedroom open 24/7, even when it’s cold outside, just to keep my CO2 levels in the healthy range otherwise it will be pushing 2000ppm in the morning.

The real "hack" lies in the IKEA STARKVIND air filters.

They're from a reputable manufacturer, are HEPA filters, and best of all, they only cost $14.99 CAD (price may vary in your country). This makes them great as *replacement filters for other air purifiers*. This is one of the things I love the most about IKEA - hackable IKEA products are available worldwide and can be easily sourced and adapted as "materials" instead of "products".

The Starkvind air purifier appears to be airflow-constrained on the fan, and not the filters they used. I put its filter (with some cardboard glued to the edges to seal the difference in size) in a Coway Mighty AP-1512HH (often recommended) and have not noticed a huge decrease in airflow at all, even though technically there is less filter area. Based on rudimentary measurements with an anemometer, the airflow is acceptable, and after about a year or more of continuous use, it's lost about 10% of the airflow after I recently changed it.

Even better, if you are so inclined, you can buy several STARKVIND filters and cut them to size/merge multiple if your purifier takes different size filters. And if you have a smaller purifier, IKEA also has the FORNUFTIG (thinner) filter for $7 that you can similarly hack.

Starkvind means Strong wind, Fornuftig means Reasonable.

Got to love their product names, as a Norwegian.

Meanwhile I have 2x AX90s in my place. Love them! Got the 2nd when I realised the special it was on was not too far from a single filter change, so it'll be fun when they're both up for refresh.

I'm addition to appreciating clean indoor air, I'm kind of preparing for the next bushfire in Melbourne - can still remember the last one, which was very very bad. I think it might happen next year, and be even worse than last time given current fuel build up. I might check out the IKEA ones to keep the AX90 filters fresh, if the IKEA filters are much cheaper to replace / run on an everyday basis.

(The Samsung units have an amazing ability to go from a very silent idle to a really bloody high CFM, on auto - currently mainly experienced when cooking).

Edit: They are stupidly cheap, found the Australian prices! Will definitely pick up a few in due time. https://www.ikea.com/au/en/cat/air-purifiers-filters-49081/

Hacking them to fit another purifier reminds me of the Apollo 13 incident, which included the astronauts having to do a McGyver hack to fit a square CO2 filter into a socket designed for a round one... using tape, hoses and other plastic items they had lying around :)

Really neat how easy IKEA products data can be gleaned, especially thanks to the online community.

I wanted to add a screen to the VINDRIKTNING[0] air quality sensor, and thanks to an existing project[1] I was able get it working[2].

[0] https://www.ikea.com/us/en/p/vindriktning-air-quality-sensor...

[1] https://github.com/Hypfer/esp8266-vindriktning-particle-sens...

[2] https://github.com/zvakanaka/vindriktning-oled-no-wifi