Emission Control Systems: Description and Operation

Emissions Classifications







The illustration shows the relationship between the different emissions classifications.
- Tier 1 (the applicable obligatory requirements, both federal and in California)
- TLEV (Transitional Low Emission Vehicle)
- LEV (Low Emission Vehicle)
- ULEV (Ultra Low Emission Vehicle)
- LEV II (Low Emission Vehicle, stage 2)
- ULEV II (Ultra Low Emission Vehicle, stage 2)
- SULEV (Super Ultra Low Emission Vehicle)
- NOx g/mile (nitrous oxides)
- CO g/mile (carbon monoxide)
- NMOG g/mile (Non-Methane Organic Gases). These are the basis of smog. In principle NMOG are hydro-carbons
- "A"symbolizes the optimal target of the car when it leaves the factory.