Open-source boards designed in KiCad by MorgenWebDigital on GitHub, from 2 repositories. A board’s address here is its repository’s there.
MorgenWebDigital/airquality
A battery-powered indoor air quality monitor. Real CO₂ from a photoacoustic sensor, VOC and NOx, temperature, humidity and ambient light, shown on a 2.13" e-paper display and sent over Bluetooth LE.
MorgenWebDigital/airqualitymini
A stationary indoor air quality sensor. Real CO₂, VOC and NOx, temperature and humidity. No display, no battery. Powered from USB-C, read out over Bluetooth LE.