Introduced in the year 2000, the Bharat Stage Emission Standards (BSES) are set by the Central Pollution Control Board under the Ministry of Environment and Climate Change. These emission standards for automobiles were made mandatory by the Government of India to keep air pollutants emitted by the internal combustion engine of vehicles under control.
How does BS6 emission norms differ from BS4?
The following are the key differences between BS4 and BS6 emission norms:
- Diesel Particulate Filter (DPF) and Selective Catalytic Reduction (SCR) are being introduced with the roll-out of Bharat Stage VI norms, which were not a part of Bharat Stage IV.
- Real Driving Emission (RDE) will be introduced in India for the first time with the implementation of Bharat Stage VI emission norms. It will measure a vehicle’s emission in real-time conditions against laboratory conditions.
- Another change that is being introduced with the implementation of Bharat Stage VI emission norms is that Onboard Diagnostics (OD) has been made mandatory for all vehicles.
- Change in the fuel used in vehicles is the major upgrade that is being brought about with the roll-out of Bharat Stage VI emission norms. A vehicle with BS6 compliant engine will require BS6 fuel. If a BS6 vehicle uses BS4-grade fuel, it won’t be able to adhere to the BS6 emission norms. Similarly, if a BS4 vehicle uses BS6-grade fuel, its engine will take a hit and increase emissions.
- The most crucial difference between BS6-grade fuel and BS4-grade fuel will be in terms of Sulphur and Nitrogen Oxide content. The sulphur traces in BS6 fuel is five times lower (10 ppm) as compared to sulphur traces in BS4 fuel (50 ppm). Further, nitrogen oxide level for BS6-grade diesel engines and petrol engines will be brought down by 70% and 25%, respectively.
THE BELOW TABLE OFFERS AN INSIGHT INTO THE CHANGE IN THE PERMISSIBLE EMISSION LEVELS OF BS6 VEHICLES COMPARED TO BS4 VEHICLES:
| Fuel Type | Pollutant Gases | BS4 (BSIV)
| BS6 (BSVI) |
| Petrol Passenger Vehicle | Nitrogen Oxide (NOx) Limit | <80mg>
| <60mg> |
| Particulate Matter (PM) Limit | – | <4.5mg/km |
| Diesel Passenger Vehicle | Nitrogen Oxide (NOx) Limit | <250mg>
| <80mg> |
| Particulate Matter (PM) Limit | <25mg> | <4.5mg/km |
| HC + NOx | <300mg> | 170mg/km |
The table below offers an insight into the implementation timelines of the emission norms:
| Emission Standard | Reference | Year of Introduction |
| India 2000 | EURO 1 | 2000 |
| Bharat Stage II (BS2) | EURO 2 | 2005 |
| Bharat Stage III (BS3) | EURO 3 | 2010 |
| Bharat Stage IV (BS4) | EURO 4 | 2017 |
| Bharat Stage V (BS5) | EURO 5 | To be skipped |
| Bharat Stage VI (BS6) | EURO 6 | 2020 |
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