IoT Based Simple Air Pollution Monitoring System We are using some simple cost effective materials to make an IoT based air pollution monitoring system. #environmental_sensing #iot #monitoring #mq135_gas_sensor COMPONENTS AND SUPPLIES Arduino UNO MQ135 Gas Sensor Buzzer Jumper wirs Breadboard 5mm LED Red 5mm LED Green 220 ohm resistors(quantity-2) NECESSARY TOOLS AND MACHINES Soldering iron (generic)-not necessary APPS AND ONLINE SERVICES Arduino IDE ABOUT THIS PROJECT This page is about how to make an air pollution monitoring system using an Arduino UNO, buzzer, LEDs and MQ135 gas sensor. Working principle: When we keep some fuels which have harmful gases like CO2, NO2 etc(when we keep an inscence stick close to this sensor), the RED LED will glow and the buzzer starts ringing else if it is good quality air around, then green LED will glow. Code is as given below: Connection diagram is...