The system consists of air sensors that sense the presence of harmful gases and compounds in the air. The components required for the Air Pollution Monitoring System are MQ135, Arduino board, OLED Display, LEDs, and buzzer. The MQ135 is one type of gas sensor that can sense NH3, NOx, alcohol, Benzene, smoke, CO2, and some other gases, these gases are harmful to human health. Arduino UNO is the main microcontroller board of this system. The gas sensor continuously measures air quality and sends data to the Arduino board. Then Arduino prints air quality value on the OLED display in the PPM unit. The LEDs and Buzzer used as indicators, that indicates the air quality is in good, Poor, or dangerous zone.