What are the 5 major pollutants regulated by the Clean Air Act?

The Central Government launched National Clean Air Programme (NCAP) as a long-term, time-bound, national-level strategy to tackle the air pollution problem which monitors 4 major pollutants, are – 

1. Sulphur Oxides (SO2)
2. Nitrogen Oxides (NO2)
3. Suspended Particulate Matter (PM10)
4. Fine Particulate Matter (PM25)

Further Readings – 

1. Air Pollutants
2. National Clean Air Programme – NCAP
3. Pollution measurement – Air Quality Index (AQI)