MQ135 Air Quality Gas Sensor Module – Harmful Gas Detector

MQ135 Air Quality Detector Sensor Module

Want your project to know when the air in a room is getting bad? The MQ135 module is a popular, low-cost gas sensor for air quality monitors, smart home projects and student FYPs. Connect it to an Arduino or ESP32 and watch it respond when the air changes.

Key Features

• Responds to gases such as ammonia (NH3), nitrogen oxides (NOx), alcohol, benzene, smoke and CO2
• Analog output (A0) for relative gas level readings
• Digital output (D0) with LM393 comparator for threshold alerts
• Onboard potentiometer to set the alarm threshold
• Power and signal indicator LEDs
• 5V operation, easy 4-pin interface: VCC, GND, D0, A0
• Works with Arduino, ESP8266, ESP32 and other microcontrollers

Common Uses

• Indoor air quality monitors
• Smoke and harmful gas alert projects
• Smart home and IoT air sensing
• Ventilation control and school/university projects

Good to Know

• The sensor has a heater, so it gets warm during use. This is normal.
• Let it warm up before taking readings. New sensors give more stable results after a longer first-time burn-in.
• Readings are relative. Calibrate in clean air for your own project. Not a certified safety or medical device.
• When using with 3.3V boards like ESP32, check that the analog output voltage suits your board's input.

Package Includes

• 1 × MQ135 Air Quality Sensor Module

Available with delivery across Pakistan, including Karachi, Lahore, Islamabad, Rawalpindi, Faisalabad and Peshawar.