ESP32 Compatible Air Quality Sensors

Air quality sensors do not all measure the same thing, so pick by the gas you actually care about. The MH-Z19 is the only true CO2 sensor here - it measures infrared absorption (NDIR) rather than estimating. The CCS811, ENS160 and AGS10 are metal-oxide VOC sensors: cheap and useful for "is the air getting stale" trends, but their eCO2 numbers are derived estimates, and they need a burn-in period and some warm-up before readings settle.

For particulates, the Sharp GP2Y1010AU0F gives an analog dust-density signal - coarse compared to a laser particle counter, but simple and cheap. The MiCS-4514 covers combustion gases like NO2 and CO with two analog channels and a heater.