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AirQuality-Humidity-PPM-Monitor-using-ESP32

An environmental monitoring system built using ESP32 that tracks:

• Temperature
• Humidity
• Gas concentration (PPM approximation using MQ2)

The system provides real-time monitoring through:

• 16x2 LCD display
• LED indicators
• Buzzer alerts
• Serial Monitor logging

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Features

• Real-time temperature and humidity monitoring using DHT22
• Air quality/gas detection using MQ2 sensor
• Automatic baseline gas calibration on startup
• Visual safety indicators using LEDs
• Audible danger alerts using buzzer
• LCD status display
• Serial Monitor diagnostics
• Dynamic threshold comparison for gas detection

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Components Used

• ESP32
• DHT22 Sensor
• MQ2 Gas Sensor
• 16x2 LCD Display
• Red LED
• Green LED
• Buzzer
• Jumper wires and breadboard

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Pin Configuration

Component	ESP32 Pin
DHT22 Data Pin	GPIO 4
MQ2 Analog Output	GPIO 34
Green LED	GPIO 16
Red LED	GPIO 17
Buzzer	GPIO 18

LCD Pins

LCD Pin	ESP32 Pin
RS	14
E	27
D4	26
D5	25
D6	33
D7	32

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Working Principle

Startup Calibration

On startup, the MQ2 sensor performs automatic calibration by averaging initial readings to determine a baseline gas level.

Monitoring

The system continuously:

• Reads temperature and humidity from the DHT22 sensor
• Reads gas concentration values from the MQ2 sensor
• Compares values against predefined safety thresholds

Safety Conditions

Danger mode activates if:

• Temperature > 45°C or < 10°C
• Humidity > 80% or < 20%
• Gas level exceeds calibrated threshold

Alert System

Status	Green LED	Red LED	Buzzer
Safe	ON	OFF	OFF
Danger	OFF	ON	ON

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Serial Monitor Output

The Serial Monitor displays:

• Temperature
• Humidity
• Gas sensor ADC values
• Current threshold
• Danger status

Example:

Temp: 31.2 C, Humidity: 58 %
Gas ADC: 1450, Threshold: 1380
DANGER ACTIVE: NO

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Project Structure

AirQuality-Humidity-PPM-Monitor-using-ESP32
├── diagram.json
├── libraries.txt
├── README.md
├── sketch.ino
└── wokwi-project.txt

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Libraries Used

• LiquidCrystal
• DHT Sensor Library

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Future Improvements

• WiFi dashboard integration
• IoT cloud monitoring
• Mobile notifications
• Historical data logging
• Graph-based analytics
• OLED/TFT display support

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Simulation

This project can be simulated using Wokwi.

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Author

Built by Junaid