Which of the following gases have atmospheric concentrations that are used to…

Concept

An Air Quality Index converts measured concentrations of prescribed ambient-air pollutants into pollutant sub-indices and then reports the dominant overall category.

Only pollutants named in the governing AQI scheme enter this calculation; not every atmospheric gas or every greenhouse gas is an AQI parameter.

Application

• Carbon monoxide (CO): included in India’s National AQI; it impairs oxygen transport in the body.

• Carbon dioxide (CO2): not one of the eight National AQI pollutants; it is primarily tracked as a greenhouse gas.

• Nitrogen dioxide (NO2): included in the National AQI; it irritates the respiratory system and is associated with combustion.

• Sulphur dioxide (SO2): included in the National AQI; it is associated with sulphur-containing fuel combustion and respiratory effects.

• Argon (Ar): not an AQI pollutant; it is a chemically inert constituent of air.

Therefore, the applicable gases are carbon monoxide, nitrogen dioxide, and sulphur dioxide.

Cross-check

The CPCB National AQI list contains CO, NO2, SO2, O3, NH3, PM10, PM2.5, and Pb. Of the gases offered here, this independently leaves CO, NO2, and SO2.