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....