1. MQ135 sensor coupled with a simple adjustable comparator circuit using a LM393 IC.
2. Detects Ammonia (NH3), Benzene, Sulfur, (SO2), Alcohol, CO2, Smoke and others in the air.
3. Designed to interface to a Arduino or other micro controllers.
4. Power: 5VDC
5. Outputs: TTL Compatible Digital & Sensor Direct Analog
6. 4 Pin .1in. Pitch Header pins for Power & Output
7. LEDs for Output and Power status indication.
8. Detection Zone: 10-300ppm

Getting started with the Air Quality Sensor (MQ-135)

Air quality check with Arduino Uno with the help of MQ135 Air Quality sensor. It is very useful in finding air quality.

Step1: Hardware required

• Arduino Uno
• Air Quality Sensor (MQ-135)
• Jumper wire

Step2: Connecting the Hardware

ARDUINO UNO                     MQ-135

Vcc                                                 Vcc

GND                                               GND

AO                                                    AO

CODE

Upload the code

int airquality = 0;
void setup()
{
Serial.begin(9600);

}
void loop()
{

int sensorValue = analogRead(A0);
Serial.print(“Air Quality = “);
Serial.print(sensorValue);

Serial.print(“*PPM”);
Serial.println();
delay(1000);
}

You can open up the serial monitor of Arduino for finding air quality as shown below:

When the air quality decreases, its value increases.

NOTE: IF you  get stray ‘223’ errors The problem is with your “ and ” characters. Replace them with ordinary quotes, ", and you should be fine.