The Ultimate DIY Air Quality Monitor: Breathe Smarter, Live Healthier

Are you truly aware of the air you breathe indoors every day? The air inside our homes and offices can be significantly more polluted than the air outside, impacting our health, focus, and overall well-being. It's time to stop guessing and start measuring.

Introducing the AirGuardian C3 Pro Kit – a powerful, compact, and fully open-source PCB designed for the ultimate DIY air quality station. Powered by the efficient ESP32-C3 controller and a suite of professional-grade sensors, this board gives you a complete, real-time picture of your environment, empowering you to create a healthier living space.

Why Choose the AirGuardian C3 Pro?

Comprehensive 7-in-1 Sensing: Why settle for one or two metrics? The AirGuardian C3 Pro measures everything that matters: Carbon Dioxide (CO2), Volatile Organic Compounds (VOCs), NOx Index, Particulate Matter (PM1.0, PM2.5, & PM10.0), Formaldehyde (CH2O), Temperature, Humidity, and Barometric Pressure.
Seamless Smart Home Integration: Built on the powerful ESPHome platform, this monitor integrates flawlessly with Home Assistant. Not a Home Assistant user? No problem! With built-in MQTT support, you can send data to any platform, dashboard, or database you choose.
Reliable & Rock-Solid: Designed with stability in mind, featuring robust power filtering with multiple decoupling capacitors and a dedicated voltage regulator. Set it up once and let it run for years.
Compact & Discreet: Its small form factor allows you to place it anywhere without clutter. The perfect foundation for a custom 3D-printed case that matches your home decor.
Fully Open & Customizable: You get the complete ESPHome configuration file. Tweak it, expand it, and make it your own. This is DIY at its best – powerful, flexible, and entirely under your control.

Technical Specifications & Connections

The AirGuardian C3 Pro is engineered for performance and ease of use for the electronics hobbyist and smart home enthusiast.

Core Components

Microcontroller: ESP32-C3 Super Mini Pro (Wi-Fi & Bluetooth LE)
Power: 5V DC input via standard pins.
Voltage Regulation: On-board AMS1117 regulator provides a clean 3.3V supply to the controller and sensors.
Power Filtering: Includes 10µF input, 22µF, and 100nF decoupling capacitors for exceptionally stable operation.

On-board Sensors

SCD40: True NDIR sensor for accurate Carbon Dioxide (CO2), Temperature, and Humidity.
SGP41: Measures Volatile Organic Compounds (VOC Index) and Nitrogen Oxides (NOx Index).
AHT20 + BMP280 Combo: A secondary sensor providing Temperature, Humidity, and precise Barometric Pressure.
PMS5003: Laser-based sensor for Particulate Matter (PM1.0, PM2.5, PM10.0).
ZE08-CH2O: Electrochemical sensor for Formaldehyde (CH2O) concentration.

Connectivity & Pinout

The board is pre-wired to connect the sensors to the optimal pins on the ESP32-C3 controller.

I2C Bus (SCD40, SGP41, AHT20/BMP280):

SCL (Clock): Connected to ESP32 Pin 9
SDA (Data): Connected to ESP32 Pin 8
Note: On-board 4.7kΩ pull-up resistors are included.

UART1 (PMS5003 Particle Sensor):

ESP32 TX (Pin 21): Connects to PMS5003 RX
ESP32 RX (Pin 20): Connects to PMS5003 TX

UART2 (ZE08-CH2O Formaldehyde Sensor):

ESP32 TX (Pin 6): Connects to ZE08-CH2O RX
ESP32 RX (Pin 7): Connects to ZE08-CH2O TX

Firmware

The device is designed to be flashed with ESPHome. We provide a complete, ready-to-use yaml configuration file to get you up and running in minutes. The firmware enables a local web server for viewing data without any smart home hub and publishes all sensor readings to MQTT for maximum compatibility.