The Air Quality Click Board™ features the MQ-135 gas sensor in its design for measuring the air quality in apartments, homes and offices. This add-on board helps you detect poisonous gases like ammonia (NH3), nitrogen oxides (NOx), benzene, CO2, smoke and others that harm the air quality. The Air Quality Click Board™ is equipped with a calibration potentiometer and a power indicator LED. It also has got a MikroBUS host socket and two jumpers. The MQ-135 sensor features a gas sensing layer constructed of tin dioxide which is an inorganic compound with the formula SnO2. Tin dioxide is known to have lower conductivity in clean air.
As the level of pollution increases in the air, the conductivity rises too. You can calibrate the Air Quality Click Board™ for the environment by adjusting the load resistance of the sensor circuit. As the concentration of the target air changes, the resistance of the sensor component also gets changed.