Smart Air Purifier with AQI Monitoring & Automatic Speed Control

Problem statement

Indoor air pollution is often worse than outdoor pollution, causing respiratory issues. Manual control of air purifiers is inefficient, as air quality can fluctuate quickly. A smart system that monitors indoor AQI and autonomously adjusts purifier settings can significantly improve indoor environmental health.

Abstract

The project integrates an MQ-series gas sensor, PM2.5 dust sensor and temperature/humidity sensor with a microcontroller to measure indoor AQI. Based on pollution levels, the system adjusts purifier fan speed using preset rules or a small ML model. A mobile dashboard displays AQI, purifier state and historical trends. Voice assistant integration allows hands-free control.

Components required

• ESP32 / NodeMCU
• MQ135 Gas Sensor
• PM2.5 Dust Sensor
• DHT22 Temperature/Humidity Sensor
• Purifier fan + motor driver
• Mobile app or web dashboard

Block diagram

Working

Sensors detect gas concentration, particulate matter and humidity. ESP32 calculates AQI and determines the appropriate fan speed (Low / Medium / High / Turbo). When pollution increases suddenly, the system boosts the purifier power. A dashboard displays data in real time, and alerts trigger when AQI crosses harmful thresholds.

Applications

• Homes, offices and classrooms
• Smart HVAC systems
• Health-focused indoor environments
• IoT environmental monitoring research