Which pollutant is NOT directly measured by the National Air Quality Index (NAQI)?
- PM2.5
- Ozone (O₃)
- Carbon Monoxide (CO)
- Carbon Dioxide (CO₂)
Answer: Carbon Dioxide (CO₂)
NAQI monitors 8 pollutants: PM10, PM2.5, NO₂, SO₂, CO, O₃, NH₃, Pb. CO₂ is a greenhouse gas but not a criteria air pollutant for NAQI. Important distinction for environmental exams. [[CPCB Guidelines]]