Monitoring and protecting high-level air in urban regions with increasing businesses, enterprises, and population have become a critical problem. This leads to the necessity for air quality monitoring and evaluation. IOT Based Air Pollution Monitoring System monitors the air quality, i.e., it measures the amount of harmful gases present in the air like CO2, smoke, ethanol, O3, VOCs over a web server using internet. The system also displays temperature and humidity. It can be installed anywhere, particularly in the industries and houses where the amount of harmful gases present is considerably high.