I suspect both! I should compare a $250 one with the $20 one

That would be a worthy HN post.

Is that something HN is interested in? I do work and research with remote environmental monitoring stations and am always comparing sensors. Currently doing a precipitation gauge intercomparison study.

I can only speak for myself and what I've seen discussed here over the years -- yes, it would be interesting. Why is better stuff is more expensive, how to make the cheap stuff work closer to the better stuff, and interesting findings from actually using them. Lessons learned are always interesting...

Please do! I just bought a couple of cheap co2 sensors on Amazon (2k positive reviews) only to find out that they may not be accurate.

It would be amazing if you or anyone really could make a comparison between different models - and show whether the cheap ones on amazon and the likes are worth it.

Very interesting.

Just test/calibrate them outside (400-ish ppm). Even if absolute measurements are bogus, they should do just fine to figure out whether it’s time to open the window..

Would be interested to find out because if its just uncalibrated plotting out the relative differences it still would be useful (e.g. seeing a X% increase on whatever scale the sensor using at night versus day could provide enough of an indicator that something is going on and more investigations are warranted.)

Also if someone is searching for PM2.5 particle monitoring:

https://smartairfilters.com/en/blog/how-accurate-are-common-...