Nice article! One small typo:

> It can be seen that all three sensors correlate very well but that the Vindriktning only shows about 65% of the PM2.5 values of the other two sensors and thus seems to considerably understate the air quality.

I think here you mean "overstate the air quality" right? Or "understate the air pollution"

Hi author! Nice write up and good analysis. However I think you missed something in the analysis.

The sensor is only accurate to +-20uG/m^3 this also means it can never reach a reading of healthy air according to the WHO specs... I think that is a bigger issue that the traffic light UI.

Apologies for picking on this issue. I am very thankful you took the time to create this article and look at the all the specifications.

Hi, thanks for the article!

Are there any non expensive sensors you could recommend? I care about the indoor air quality but it gets very pricey. I have Awair at home but it covers only one room and the unit runs $300 a piece :(

Not the OP, but I tried a bunch of these and wrote up details here: https://www.reddit.com/r/AirQuality/comments/ikf1ed/are_ther...

Most of them (including the awair) are complete crap.

I found one that seems okay and is also one of the cheaper ones.

I use and like this one best: https://www.amazon.com/dp/B07DHXQXGK/

Simple screen with relevant details, no crappy 2.4ghz wifi, no crappy app, etc. it just works.

Aqmd tested Awair and it came with really good results actually. I’m struggling to find the report online at the moment.

It doesn’t tell you AQI or PM2.5 so it’s results may be consistent but are fairly useless.

I’d be curious what report you saw, last I looked the consistency of the results wasn’t even that great either.

Awair's phone app lists both AQI and PM2.5, and PM2.5 is available on the device itself by pressing buttons to change the display. Somewhat confusingly, the indoor AQI is on the Outdoor tab.

Cool - this must be new?

When I owned one they only had some proprietary quality score and how it related to PM2.5 or AQI was not listed.

This one?: https://www.aqmd.gov/aq-spec/evaluations/summary-pm

Unfortunately no, not this one. I also came across these but I recall a several page long reports for each device individually. Tested in controlled environment and compared with some professional $20k+ sensor. I wish I could deliver better than promises lol.

That looks like the Eve Room https://www.evehome.com/en/eve-room

I'm a fan of the airgradient, they offer a very nice DIY. You can build a quality sensor for under $50.

https://www.airgradient.com/diy/

Components:

    Wemos D1 Mini USD 2.24
    Wemos OLED display USD 2.47
    Plantower PMS5003 PM Sensor USD 13.89
    Senseair S8 CO2 Sensor USD 28.00
    SHT30 or SHT31 Temperature and Humidity Sensor Module USD 2.55

I think the lead article was posted by the founder of airgradient. I've had some email exchanges with him, he is supportive and helpful.

I can also attest to the inexpensive simplicity (and decent reliability) of the AirGradient sensors.

That looks like a great kit! It's that Senseair S8 a real CO2 sensor though? It's a bit cheap, most in that price range are just estimated (eCO2)

The S8 is a high quality NDIR CO2 sensor often used in professional air quality monitors.

I am not aware of a good and low-cost wifi connected sensor but as I mentioned it is relatively easy to build one yourself.

If you don't want to buld yourself, there are a few relatively good non-connected PM 2.5 sensors for example the "SmartMi PM2.5 Air Quality Monitor" that I can recommend. It costs around USD 30 here in Asia.

You might be interested in the author's DIY kits: https://www.airgradient.com/diy

I’ve used this one [1] then ordered similar ones from Ali express after getting the Adafruit one working.

1. https://www.adafruit.com/product/3686?gclid=CjwKCAiAhreNBhAY...

I can second this one, I soldered four wires to connect it to an ESP8266 and flashed ESPhome and that was it, it's worked fine for months.

I like my Netatmo. I see that it costs $200 on Amazon for main module + you can connect 3 additional ones for other rooms — they cost $86 each. It shows CO2 (notifies when it's high on smartphone), temperature, relative humidity and noise level.

I've been looking at ordering a variety of environmental sensors from Seeed Studio's Grove line. They look approachable and affordable, but I cannot vouch for their quality.

https://www.seeedstudio.com/Grove-Laser-PM2-5-Sensor-HM3301....

Are you recording sensors output?

If the sensors have been calibrated in software, wouldn't you get the uncalibrated values?

I assume you're in some way connected to the site maintainers (or it's just you). Please, tell them the site is broken, as it does not display anything without JS.

There's nothing dynamic on the page (in fact, on most pages on the site). It's mostly text and images, a user doesn't need to run your blobs of code to see them.

It would be great to hear some alternative suggestions for a consumer air quality meter that is accurate, reliable. I.e. are the AirThings products good? Or do you have any other recommendations?

I purchased two Airthings View Plus monitors about a month ago. We had a subslab depressurization system installed to mitigate Radon in the basement. The company offered continuous monitoring for $300/yr. Instead I decided to purchase monitors and keep an eye on it myself.

It's hard to know how good the products will be long-term, but the app and charting is pretty good. You can download reports via their web dashboard. I've turned off all notifications except for the CO2 monitor. The ePaper screen is legible, but the text is a little rough around the edges.

Here's what it tracks:

- Radon

- PM 2.5

- VOC

- CO2

- Humidity

- Temperature

- Pressure

I will say that the View Plus is Airthings most expensive product. If you don't care about PM 2.5 or Radon monitoring, they have significantly cheaper options.

Should we just consider buying an air purifier?

Currently in Bay Area where air outside seems good but these apartments seem poorly ventilated, old fixtures, old floors, lots of electronics, etc.

Have you tested other air quality sensors, if so have you tested the uHoo?

https://getuhoo.com/

Given that the correlation is pretty good, I wonder if it's sufficient to just add a compensating factor to get a better sense of air quality.

Append this info in your article please. It's a very useful suggestion for future readers.

Are there any air quality devices that work well outdoors in all kind of weather?