Monitoring Home Pollutants with Industrial Precision

The thought of breathing in nasty chemicals or allergens isn’t exactly appealing. So, with their natural tendency to seek solutions to problems, engineers often try to solve this one by building their own air quality monitoring stations. But many times these DIY systems have parts sourced from distributors that are better known for low prices than they are for quality. This raises the question: how valuable is the data captured by these budget sensors?

That is one of the problems that Project Aura is attempting to solve. The system is designed to be assembled by the user, but it avoids the common “sensor zoo” approach. Instead of mixing multiple inexpensive modules that drift and interfere with each other, the device centers on a single industrial-grade Sensirion SEN66 environmental module. That sensor measures particulate matter across multiple size ranges, as well as carbon dioxide, volatile organic compounds, nitrogen oxides, temperature, and humidity. An optional SFA30 module adds direct formaldehyde detection, a pollutant often associated with new furniture and construction materials.

The project’s goal is not just to collect numbers, but to produce meaningful data about the air people breathe. Elevated CO₂, for example, has been linked to reduced concentration and fatigue, while fine particulate matter can enter the bloodstream and trigger inflammation. Aura also calculates absolute humidity and tracks barometric pressure trends, features aimed at helping users understand respiratory comfort and even weather-related headaches.

The monitor is built around a Waveshare ESP32-S3 board with a 4.3-inch touchscreen display. The interface, built using the LVGL graphics library, presents dashboards, historical pressure graphs, and color-coded air quality indicators. A real-time clock keeps accurate time even when disconnected from the internet.

Using MQTT auto-discovery, the monitor can appear directly inside Home Assistant with more than 20 sensors and controls, including AQI values, PM2.5 readings, CO₂ levels, and display settings. Importantly, all data remains local rather than being uploaded to a manufacturer’s cloud service.

Standardized Grove and Qwiic connectors eliminate soldering, and even the power stabilization capacitor simply inserts into a screw terminal. The total cost runs roughly $170 to $200 depending on options, putting it near consumer-grade monitors but with laboratory-grade sensing and open-source firmware.

If you want to learn more about how you can make this air quality monitor for yourself, be sure to check out the project write-up.