National Air Quality Index
About National Air Quality Index
- Air Quality Index is a tool for effective communication of air quality status to people in terms, which are easy to understand. It transforms complex air quality data of various pollutants into a single number (index value), nomenclature and colour.
- There are six AQI categories, namely Good, Satisfactory, Moderately polluted, Poor, Very Poor, and Severe. Each of these categories is decided based on ambient concentration values of air pollutants and their likely health impacts (known as health breakpoints). AQ sub-index and health breakpoints are evolved for eight pollutants (PM10, PM2.5, NO2, SO2, CO, O3, NH3, and Pb) for which short-term (up to 24-hours) National Ambient Air Quality Standards are prescribed.
- Based on the measured ambient concentrations of a pollutant, sub-index is calculated, which is a linear function of concentration (e.g. the sub-index for PM2.5 will be 51 at concentration 31 µg/m3, 100 at concentration 60 µg/m3, and 75 at a concentration of 45µg/m3 ). The worst sub-index determines the overall AQI. AQI categories and health breakpoints for the eight pollutants are as follow:
Air Quality Index (AQI)
The AQI is an index for reporting daily air quality.
It focuses on health effects one might experience within a few hours or days after breathing polluted air.
AQI is calculated for eight major air pollutants:
- Ground-level ozone,
- Carbon monoxide,
- Sulfur dioxide,
- Nitrogen dioxide,
* Ground-level ozone and airborne particles are the two pollutants that pose the greatest threat to human health in India.