pollution standards for in use vehicles have been prescribed under
Rule 115(2) of Central Motor vehicles Rules, 1989. They are:
Petrol / CNG / LPG Vehicles:
a) Idling Carbon Monoxide emission limit for all two and three-wheeled
vehicles should not exceed 4.5%.
b) Idling Carbon Monoxide Emission limit for all vehicles other
than two and three- wheelers should not exceed 3%.
Smoke density for all diesel driven vehicles should not exceed
65 hartridge Smoke Units.