Which one of the following is included while estimating Air Quality Index (AQI)?

The correct option is NO₂ Nitrogen dioxide.

The Air Quality Index (AQI) is a standard tool used by environmental and government agencies to report daily air quality and communicate potential health risks to the public. To calculate the AQI, the concentrations of major air pollutants that have direct and immediate impacts on human health are monitored.

Generally, the estimation of the AQI includes the following criteria pollutants:
1. Particulate Matter (both PM_2.5 and PM₁₀)
2. Nitrogen Dioxide (NO₂)
3. Ground-level Ozone (O₃)
4. Carbon Monoxide (CO)
5. Sulfur Dioxide (SO₂)
6. Ammonia (NH₃)
7. Lead (Pb)

Among the choices provided, Nitrogen dioxide (NO₂) is a prominent gaseous pollutant formed during high-temperature combustion processes in motor vehicles and power plants. It is highly reactive and directly linked to respiratory ailments, making its measurement critical for daily health assessments. Other nitrogen oxides like Nitrous oxide (N₂O), Dinitrogen trioxide (N₂O₃), and Dinitrogen pentoxide (N₂O₅) are not included in the standard estimation of the AQI.