Remember the primary health effects of common air pollutants:
CO: Chemical asphyxiant (binds to hemoglobin).
SO$_2$: Respiratory irritant, causes acid rain.
NO$_2$: Strong respiratory irritant, linked to acute respiratory infections, causes acid rain and smog.
Particulates (PM2.5, PM10): Penetrate deep into lungs, cause cardiovascular and respiratory issues.