Ya, my AirGradient ONE is $200 and has been one of the best investments in my home. Using it, I discovered how the drying polyester clothes wrecks the indoor air quality and how not to burn baking oils by controlling temps better.
Drying polyester clothes releases CO2 to unhealthy levels?
Probably referring to particulate matter. The AirGradient measures PM2.5. I happen to have an air purifier near my W/D and it catches a lot of lint in the prefilter.