Air Quality Index (AQI) is represented in

AUnit of microgram per metre cube

BUnit of ppm

CPercentage

DNumber ✓ Correct

Correct answer: (D) Number

Explanation

The Air Quality Index is expressed as a single number.

That number is a dimensionless value on a fixed scale from zero upward.

It is not given in micrograms per cubic metre, which is how raw concentrations are stated.

It is not given in parts per million, another concentration unit.

It is not given as a percentage.

Higher index numbers fall into bands from good to severe, each colour-coded.

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