5978

A compact, low-cost IoT device built on ESP32 that monitors indoor air quality in real time measuring CO2 levels, temperature, and humidity and instantly sends Telegram alerts when unsafe thresholds are detected. Designed with deep sleep optimization for battery-powered, always-on deployment.

Indoor air quality is a silent health concern in homes, classrooms, and offices. This project presents a practical ESP32-based monitoring system using the MQ135 gas sensor and DHT22 for temperature and humidity. Readings are displayed on a 0.96" OLED screen for local visibility.

What makes this build unique is the combination of three features rarely seen together in a single project:

  1. Telegram Bot Alerts — instant notification when CO2 or temperature exceeds safe limits
  2. Google Sheets Logging — automatic data logging for trend analysis over time
  3. Deep Sleep Mode — ESP32 wakes only to take readings, dramatically extending battery life

The entire build costs under €10 and can be assembled by any electronics enthusiast. Full schematics, Arduino IDE code, and setup instructions will be provided.