Awareness of daily levels of air pollution is important to the citizens, especially for those who suffer from illnesses caused by exposure to air pollution. Further, success of a nation to improve air quality depends on the support of its citizens who are well-informed about local and national air pollution problems and about the progress of mitigation efforts. Thus, a simple yet effective communication of air quality is important. The concept of an air quality index (AQI) that transforms weighted values of individual air pollution related parameters (e.g. SO2 , CO, visibility, etc.) into a single number or set of numbers is widely used for air quality communication and decision making in many countries.
After reviewing literature (on AQI), air quality monitoring procedures and protocols, Indian National Air Quality Standards (INAQS), and dose-response relationships of pollutants, an AQI system is devised. The AQI system is based on maximum operator of a function (i.e. selecting the maximum of subindices of individual pollutants as an overall AQI). The objective of an AQI is to quickly disseminate air quality information (almost in real-time) that entails the system to account for pollutants which have short-term impacts. Eight parameters (PM10, PM2.5, NO2 , SO2 , CO, O3 , NH3 , and Pb) having short-term standards have been considered for near real-time dissemination of AQI.