Atmospheric concentrations of which of the following gases are used for the calculation of Air Quality Index (AQI) in the urban regions ?

The Air Quality Index is calculated from pollutants like carbon monoxide, nitrogen dioxide and sulphur dioxide among others.

Carbon monoxide is a monitored index pollutant from incomplete fuel combustion.

Nitrogen dioxide from vehicles and power plants is another key index pollutant.

Sulphur dioxide, mainly from coal burning, is also included in the index.

Carbon dioxide is a greenhouse gas but is not part of the Air Quality Index.

Argon is an inert gas of the atmosphere and plays no role in the index.