Formula to calculate air quality index?

Answer 1

I=

= ( (Ihigh - Ilow) * (C - Clow) / (Chigh - Clow) ) + Ilow

is used, where:

I = the (Air Quality) index,

C = the pollutant concentration,

Clow= the concentration breakpoint that is ≤ C,

Chigh= the concentration breakpoint that is ≥ C,

Ilow= the index breakpoint corresponding to Clow,

Ihigh= the index breakpoint corresponding to Chigh.