Just for reference, NIOSH recommends 0.016 ppm as the max exposure limit for a workday. CARB recommends a max safe level of 0.05 ppm. WHO recommends max level of 0.08 ppm for 30 minutes, etc.

0.3 ppm is extremely high for chronic exposure.

After these words I'm seriously starting to doubt the correctness of the device. I can't believe I wasn't able to find any indoor location with a low enough concentration for below 0.1 ppm, or only outdoors. I mean, these are rooms where I, my colleagues, friends and family are non-stop, we should all be good as one by now with those concentrations.

1 ppm in air = 1.24 mg/m3 @ 25° C

If you're measuring 0.1 on the meter, that's about 0.08ppm (still pretty high).

However, I've read the reviews and dug a bit deeper, talked to some people. Basically, that value might be elevated by some unknown amount, but the device should not be trusted for the absolute levels.

Equally if my so-called 100% natural mattress is giving of fumes, I'd like to know about it! Because I'm certain the living room furniture is doing so.

I used https://acsbadge.com/ to do a highly-accurate one time test of my home and was happy with the results. Piece of mind to determine if you have a potential issue or not. They also give guidance on how to interpret the numbers and what 'safe' means (results are in ppm concentration accurate to 0.002 ppm).

Typically it's around 300CFM before you should consider a mechanical make-up air device (gravity activated or a makeup air fan tied to the hood activating).

I've ordered an awair, I think it does vocs but not sure it does them in any specificity.

And I think the only real solution is venting. Open a window. Other than identifying the source and removing it of course. But in many places I think it's wall materials, furniture, etc

Dhh had a talk on indoor air quality you may find useful.

https://www.amazon.com/Air-Pollution-Formaldehyde-Detector-T...

I tested my home using a badge from this company: https://acsbadge.com/ They are not cheap ($60 for one test), but it's accurate to 2 ppb and will give you an idea what your chronic home exposure is and if changes are needed.

Or for ice cream sales -- next to a children's play area.

i may buy a foobot[1] one day, as it was highly rated in recent studies on pm measurements, and has an api.

[0] https://www.airthings.com/wave-plus [1] https://foobot.io/

Airthings looks interesting. I'm curious to know of any reviews of their accuracy.

i'm a little less concerned about accurate co2 levels, since mitigation is straightforward (open a window). even imperfect co2 readings are good enough to signal when to open a window (around 800-1000 ppm, or ~2x ambient co2 levels).

voc's and particulate matter are more my nemesis, as my lungs are more sensitive to that stuff. beyond knowing generally how bad the air is, i'd like to be able to figure out what is causing the bad air and how to mitigate it. information there seems lacking right now.

i'd trust the radon sensor in the airthings more than the voc/co2 sensor, since radon is what they're known for. the voc/co2 sensor is probably the cheaper type used in most consumer air quality monitors, so it's good directionally but is not strictly accurate/precise.

and this is the study that foobot themselves reference: https://cdn-foobot.pressidium.com/wp-content/themes/foobot/a...

My co2 sensors have no connection either: https://www.amazon.com/Hydrofarm-Autopilot-Desktop-Monitor-L...