MQ-135 Air Quality/Gas Detector Sensor Module For Arduino

Detects multiple gases: NH₃, benzene, alcohol, CO₂, NOₓ, smoke
Provides analog and digital outputs
Operates at 5V DC
Adjustable sensitivity via onboard potentiometer
Requires preheating (~24 hours) for accurate readings
Compact and easy to integrate

SKU: aa0241 Categories: Gas and Dust Sensor, Sensors Tags: Arduino, Gas and Dust Sensor, Sensors

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Description

If you are want to make a device that is used to detect Ammonia, Sulphide, and Benzene steam, also sensitive to smoke and other harmful gasses from the desired distance, then this sensor is needed for you.

The MQ 135 Air Quality Detector Sensor Module For Arduino has lower conductivity in clean air. When the target combustible gas exists, the conductivity of the sensor is higher along with the gas concentration rising.

Convert the change of conductivity to the corresponding output signal of gas concentration. The MQ135 gas sensor has a high sensitivity to Ammonia, Sulphide, and Benzene steam, also sensitive to smoke and other harmful gases.

It is at a low cost and suitable for different applications such as harmful gases/smoke detection.

Features :

Sensitivity to Ammonia, Sulphide, and Benzene steam
With signal output instructions
The TTL output signal is a low level
Analog 0 ~ 5 v voltage output, the higher the concentration, the higher the voltage
Color is showing pictures.
Sensitive for benzene, alcohol, smoke
Fast response and recovery
Adjustable sensitivity
Signal output indicator
Output voltage boosts along with the concentration of the measured gases increases.

Package Includes :

1 x MQ 135 Air Quality Sensor Module.

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Pin Connections

1 Table

Pin Connections Table 1

Board	Sensor Pin	Connection
MQ-135	VCC/GND/AOUT	5V / GND / board analog pin (see per-board note)

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MQ-135 Air Quality/Gas Detector Sensor Module For Arduino

7 Examples • C/C++ | Boards: Arduino Uno, Arduino Nano, Arduino Mega, ESP32, ESP8266, STM32, Raspberry Pi Pico

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MQ-135 Air Quality/Gas Detector Sensor Module For Arduino - Arduino Uno

MQ-135 Air Quality/Gas Detector Sensor Module For Arduino - Arduino Nano

MQ-135 Air Quality/Gas Detector Sensor Module For Arduino - Arduino Mega

MQ-135 Air Quality/Gas Detector Sensor Module For Arduino - ESP32

MQ-135 Air Quality/Gas Detector Sensor Module For Arduino - ESP8266

MQ-135 Air Quality/Gas Detector Sensor Module For Arduino - STM32

MQ-135 Air Quality/Gas Detector Sensor Module For Arduino - Raspberry Pi Pico

📄 File: mq-135_air_quality/gas_detector_sensor_module_for_arduino_-_arduino_uno.inoArduino Uno

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1//ekostra.com

2//electronics store in egypt

3//+201008896258

5// Analog pin: A0 on Arduino Uno (ADC range 0-1023, reference 5.0V)

6#define MQ_PIN A0

8void setup() {

9 Serial.begin(115200);

10 Serial.println("Warming up sensor (needs ~20-60s to stabilize)...");

11}

13void loop() {

14 int raw = analogRead(MQ_PIN);

15 float voltage = raw * 5.0 / 1023.0;

17 Serial.print("MQ-135 (air quality) raw ADC: "); Serial.print(raw);

18 Serial.print(" Voltage: "); Serial.print(voltage);

19 Serial.println(" V (higher = more gas detected; calibrate a clean-air baseline for real ppm)");

21 delay(1000);

22}

📄 File: mq-135_air_quality/gas_detector_sensor_module_for_arduino_-_arduino_nano.inoArduino Nano

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5// Analog pin: A0 on Arduino Nano (ADC range 0-1023, reference 5.0V)

6#define MQ_PIN A0

8void setup() {

9 Serial.begin(115200);

10 Serial.println("Warming up sensor (needs ~20-60s to stabilize)...");

11}

13void loop() {

14 int raw = analogRead(MQ_PIN);

15 float voltage = raw * 5.0 / 1023.0;

17 Serial.print("MQ-135 (air quality) raw ADC: "); Serial.print(raw);

18 Serial.print(" Voltage: "); Serial.print(voltage);

19 Serial.println(" V (higher = more gas detected; calibrate a clean-air baseline for real ppm)");

21 delay(1000);

22}

📄 File: mq-135_air_quality/gas_detector_sensor_module_for_arduino_-_arduino_mega.inoArduino Mega

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1//ekostra.com

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5// Analog pin: A0 on Arduino Mega (ADC range 0-1023, reference 5.0V)

6#define MQ_PIN A0

8void setup() {

9 Serial.begin(115200);

10 Serial.println("Warming up sensor (needs ~20-60s to stabilize)...");

11}

13void loop() {

14 int raw = analogRead(MQ_PIN);

15 float voltage = raw * 5.0 / 1023.0;

17 Serial.print("MQ-135 (air quality) raw ADC: "); Serial.print(raw);

18 Serial.print(" Voltage: "); Serial.print(voltage);

19 Serial.println(" V (higher = more gas detected; calibrate a clean-air baseline for real ppm)");

21 delay(1000);

22}

📄 File: mq-135_air_quality/gas_detector_sensor_module_for_arduino_-_esp32.inoESP32

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5// Analog pin: 34 on ESP32 (ADC range 0-4095, reference 3.3V)

6// SAFETY: this module can output up to 5V, but ESP32's ADC input max is 3.3V.

7// Power the module from the board's 3.3V pin instead of 5V, OR add a simple

8// resistor voltage divider on the analog output before wiring it in.

9#define MQ_PIN 34

11void setup() {

12 Serial.begin(115200);

13 Serial.println("Warming up sensor (needs ~20-60s to stabilize)...");

14}

16void loop() {

17 int raw = analogRead(MQ_PIN);

18 float voltage = raw * 3.3 / 4095.0;

20 Serial.print("MQ-135 (air quality) raw ADC: "); Serial.print(raw);

21 Serial.print(" Voltage: "); Serial.print(voltage);

22 Serial.println(" V (higher = more gas detected; calibrate a clean-air baseline for real ppm)");

24 delay(1000);

25}

📄 File: mq-135_air_quality/gas_detector_sensor_module_for_arduino_-_esp8266.inoESP8266

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1//ekostra.com

2//electronics store in egypt

3//+201008896258

5// Analog pin: A0 on ESP8266 (ADC range 0-1023, reference 3.3V)

6// SAFETY: this module can output up to 5V, but ESP8266's ADC input max is 3.3V.

7// Power the module from the board's 3.3V pin instead of 5V, OR add a simple

8// resistor voltage divider on the analog output before wiring it in.

9#define MQ_PIN A0

11void setup() {

12 Serial.begin(115200);

13 Serial.println("Warming up sensor (needs ~20-60s to stabilize)...");

14}

16void loop() {

17 int raw = analogRead(MQ_PIN);

18 float voltage = raw * 3.3 / 1023.0;

20 Serial.print("MQ-135 (air quality) raw ADC: "); Serial.print(raw);

21 Serial.print(" Voltage: "); Serial.print(voltage);

22 Serial.println(" V (higher = more gas detected; calibrate a clean-air baseline for real ppm)");

24 delay(1000);

25}

📄 File: mq-135_air_quality/gas_detector_sensor_module_for_arduino_-_stm32.inoSTM32

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5// Analog pin: PA0 on STM32 (ADC range 0-4095, reference 3.3V)

6// SAFETY: this module can output up to 5V, but STM32's ADC input max is 3.3V.

7// Power the module from the board's 3.3V pin instead of 5V, OR add a simple

8// resistor voltage divider on the analog output before wiring it in.

9#define MQ_PIN PA0

11void setup() {

12 Serial.begin(115200);

13 Serial.println("Warming up sensor (needs ~20-60s to stabilize)...");

14}

16void loop() {

17 int raw = analogRead(MQ_PIN);

18 float voltage = raw * 3.3 / 4095.0;

20 Serial.print("MQ-135 (air quality) raw ADC: "); Serial.print(raw);

21 Serial.print(" Voltage: "); Serial.print(voltage);

22 Serial.println(" V (higher = more gas detected; calibrate a clean-air baseline for real ppm)");

24 delay(1000);

25}

📄 File: mq-135_air_quality/gas_detector_sensor_module_for_arduino_-_raspberry_pi_pico.inoRaspberry Pi Pico

827 characters

1//ekostra.com

2//electronics store in egypt

3//+201008896258

5// Analog pin: 26 on Raspberry Pi Pico (ADC range 0-4095, reference 3.3V)

6// SAFETY: this module can output up to 5V, but Raspberry Pi Pico's ADC input max is 3.3V.

7// Power the module from the board's 3.3V pin instead of 5V, OR add a simple

8// resistor voltage divider on the analog output before wiring it in.

9#define MQ_PIN 26

11void setup() {

12 Serial.begin(115200);

13 Serial.println("Warming up sensor (needs ~20-60s to stabilize)...");

14}

16void loop() {

17 int raw = analogRead(MQ_PIN);

18 float voltage = raw * 3.3 / 4095.0;

20 Serial.print("MQ-135 (air quality) raw ADC: "); Serial.print(raw);

21 Serial.print(" Voltage: "); Serial.print(voltage);

22 Serial.println(" V (higher = more gas detected; calibrate a clean-air baseline for real ppm)");

24 delay(1000);

25}

Project Notes:

Analog air-quality sensor (CO2, ammonia, benzene, smoke). Needs warm-up for stable readings.

Specification

WeightWeight	6 g
Dimensions	3,2 × 2,4 × 1,8 cm
Product Name	MQ-135 Air Quality / Gas Detector Sensor Module
Type	Gas / Air Quality Sensor Module
Model	MQ-135
Sensing Gas	NH₃, NOx, Alcohol, Benzene, Smoke, CO₂ (air quality)
Operating Voltage	5 V DC
Output Type	Analog and Digital
Detection Range	10–1000 ppm (typical for air quality gases)
Heating Element	Built-in Heater for Gas Detection
Response Time	<10 s (typical)
Operating Temperature	-10°C to +50°C
Material	PCB Module with Sensor and Components
Applications	Air Quality Monitoring, Gas Leakage Detection, Arduino / DIY Electronics, Environmental Projects
Package Contents	1× MQ-135 Air Quality / Gas Detector Sensor Module