If multiple pollutants are measured, the calculated AQI is the highest value calculated from the above equation applied for each pollutant.whereIThe (air quality) index,
CThe pollutant concentration,
ClowThe concentration breakpoint that is ≤C,
ChighThe concentration breakpoint that is ≥C,
IlowThe index breakpoint corresponding to Clow,
IhighThe index breakpoint corresponding to Chigh.