I wanted an air quality monitor I can read from across the room, and I wanted it to look like something from a Fallout vault.

AIR PRO reads CO2, particles (PM1.0 to PM10), VOC, NOx, temperature and humidity every 2 seconds. It turns all of that into one simple status: OPTIMAL, NORMAL, FAIR, CAUTION, WARNING or CRITICAL. It also tells you the main problem, for example "MAIN THREAT: CO2, VENTILATE ROOM".

Everything runs on CircuitPython. No cloud, no app. WiFi is only used for a few seconds every hour to get the time.

Full code, parts list and photos: github.com/ostgate/air-pro

Parts

• Adafruit Qualia ESP32-S3 for TTL RGB-666 Displays
• 4" 720x720 square TFT display (RGB666)
• Sensirion SEN66 (CO2, PM, VOC, NOx, temperature, humidity)
• Adafruit SHT45 Temperature and Humidity Sensor (STEMMA QT)
• Adafruit I2C QT Rotary Encoder with seesaw
• STEMMA QT / Qwiic cables
• USB-C cable and a USB charger
• A small wooden box (for now)

All sensors and the encoder share one I2C bus through STEMMA QT cables. No soldering needed.

Build

The case is a small wooden box I had at home. The display sits in the door, with the Qualia board on its back. The SHT45 and SEN66 are mounted on the outside wall of the box, so they breathe room air and do not get heated by the board and the backlight. The rotary encoder shaft comes out of the top.