I got this model several months back and have been really happy with it: https://smile.amazon.com/gp/product/B01FYWU2IS/

I got it to monitor CO2 levels in a house without central air. It's pretty amazing how quickly it rises without the air on or a window open. If the air in a room feels "stuffy", it's probably over 1000 ppm.

Yep, that's the one I have. It's fantastic.

It says the CO2 range is from 0-5000 ppm, but exhaled breath has a much higher concentration (according to another comment). Are you able to accurately measure the inhaled concentration in case the breathing happens in a confined space (e.g. helmet or under a blanket, etc.)

I don't use it for confined spaces, so 5000 ppm is plenty for me. If any building I am in is over 5000 ppm I need to leave immediately!

https://www.burntec.com/images/co220b.jpg

in the unlikely event someone manages to shove that thing inside of their helmet, do they _need_ an accurate measurement? if it hits 5000, it can just be read as "way too much".

I have been considering making a CO2 sensor myself using commercially available CO2 detectors [1] , [2] and an Arduino or similar microcontroller, insructions for which abound on the intertubes [3], [4]. Such a device can be made fairly inexpensively.

However, there is a known issue in calibrating the device, as the IR emitter and light sensor change characteristics over time. The calibration requires immersing the device in nitrogen or pure CO2 and is costly and complex. The workaround is to calibrate the device outdoors where there is an assumed 400 ppm CO2.

[1] https://www.co2meter.com/collections/0-1-co2

[2] https://www.epluse.com/en/products/co2-measurement/co2-senso...

[3] https://www.dfrobot.com/blog-70.html

[4] https://www.youtube.com/watch?v=V1uOHOcVZrE

Awair Glow is a very user friendly/cheap one: https://getawair.com/pages/awair-glow

It has an app (and an API) and monitors CO2, humidity, temp, and VOCs. I like it a lot. For me, it mostly serves as a reminder to open the door for a few minutes before bed and let some fresh air in.

I have an Awair (the regular one, not the glow), it doesn't work with Ubiquiti wifi gear unless you turn on legacy mode for the access points.

Had I known that before I bought it I wouldn't have done so.

I'd love a good looking consumer device like this, especially if it synced with Apple Health and/or Homekit or otherwise allowed data export, but all (Netatomo, Awair, Uhoo, etc) seem to get very poor reviews on Amazon, often claiming they are inaccurate. Has anyone seen a good comparison of whats out there with a suggestion for the best?

Dhh recommends awair highly. Convinced me to get one, he tested a lot.

Hasn't arrived yet so I can't comment directly

https://m.youtube.com/watch?v=MRqh8oLY7Ik

I can also recommend that talk and the Awair unit seems to live up to the praise. I know some might suspect shilling by DHH for this product, but given I owe the last 10 years of my career to him, when he speaks I listen a bit closer than normal.

I've been opening the bedroom window before going to sleep but I wonder if it really matters during a normal sleep cycle.

Thanks for the link. I'm getting one.

I have a foobot.

https://www.amazon.com/Foobot-Quality-Monitor-Homeowners-Ren...

I believe you can hook it up to IFTTT and turn on the AC etc if levels are high. You can get real time stats, historical reporting...If you don't want to keep looking at your mobile device it will light up if the air quality is bad.

It also has a VOC monitor, which is rare. I have a new construction house and the VOC was pretty much deadly.

Note that that one does not measure CO2.

Yep, I made that mistake too. They have estimated CO2.

A many others have said... getawair.com seems to have different monitors for this. DHH swears by them. They also just look better imo.

More comprehensive - https://www.amazon.com/Awair-2nd-Invisible-Quality-Chemicals...

Cheaper (smart plug version) - https://www.amazon.com/Awair-Glow-Breathe-Quality-Monitor/dp...