BS4 vs BS6: The Pollutions Emission Norms Difference You Should Know

With an increase in the number of vehicles on the road, the pollution level has risen as well. The use of fuel, poor transportation systems and rapid industrialization have led to an increase in pollution, especially in metropolitan cities.

To keep a tab on the rising pollution levels, the Central Pollution Control Board under the Ministry of Environment, Forest and Climate Change came up with a pollution emission standard termed Bharat Stage Emission Standards (BSES) for the regulation of air pollutants from the internal combustion of engines. Learn more about the pollution emission norms and the difference between BS4 and BS6.

What is BSIV?

BSES is the government body that keeps a check on the emission from motor vehicles. They are responsible for introducing emission norms to regulate the pollution levels.

The organization came up with the first norm in 2000 after which a series of emission norms have been introduced. BSIV is one of the emission norms that came into effect in 2017 and has stricter standards when compared to the earlier norms. The AHO (Automatic Headlamp On) is one of the norms that was included in the BS14 emission standards.

What is BSVI?

After the introduction of BS2, BS3 and BS4, the Bharat Stage Emission Standards (BSES) introduced BS6 to regulate the emission from vehicles plying in the country. BSVI norms launched by the Central Pollution Control Board in the year 2020 is the sixth iteration.

While the first three emission norms were set up at a regular interval, both BS4 and BS6 were launched after a substantial leap in order to move to better emission norms.

Difference Between BS6 and BS4

BS6 and BS4 are emission norms that basically tells about the permissible limit for air pollutants that are emitted from motor vehicles. However, there’s some difference between the two norms. For instance, the BS6 norms are comparatively stricter than the BS4 norms. Both BS6 and BS4 have different permissible emission levels. The table below illustrates the permissible emission levels for both BS4 and BS6 norms:

Fuel Type Pollutant gases BS6 BS4
Petrol Passenger Vehicle Nitrogen Oxide (NOx) Limit <60mg> <80mg>
Petrol Passenger Vehicle Particulate Matter (PM) Limit <4.5mg/km –
Diesel Passenger Vehicle Nitrogen Oxide (NOx) Limit <80mg> <250mg>
Diesel Passenger Vehicle Particulate Matter (PM) Limit <4.5mg/km <25mg>
Diesel Passenger Vehicle HC + NOx 170mg/km <300mg>

BS4 vs BS6 Emission Norms

To keep a check on the rising pollution levels, the government introduced BS6 pollution norms. BS6 norms came into effect from 1 April 2020 to address the growing concerns related to air pollution. Here is the key difference between BS6 and BS4:

  1. While BSIV and BSVI both set maximum emission limits, the BS4 emission norms allow a vehicle to emit nitrogen oxide not more than 80mg/km and the BS6 emission norms allow a motor vehicle to not emit more than 60mg/km.

  2. When it comes to particulate matter for petrol vehicles, BS6 emission limits it to 4.5mg/km.

  3. For diesel vehicles, the permissible emission limit has been significantly reduced with the BS6 norms. For diesel vehicles, the limit for NOx is 250mg/km in BS4 norms whereas, with BS6 norms, it has been reduced to 80mg/km.

  4. The limit for HC+NOx has also been reduced to 170mg/km from 300mg/km with the introduction of BS6 emission limits.

  5. When it comes to particulate matter for diesel vehicles, the emission limit is 25mg/km for BS4 norms and has been reduced to 4.5mg/km with BS6 norms.

  6. In comparison to BS4, the BS6 fuel has less sulphur and NOx content, both of which are present in petrol and diesel.

  7. The sulphur content in BS4 fuel is 50 ppm whereas it is 10 ppm in the case of BS6 fuel.

  8. For nitrogen oxides, the permissible limit has been reduced in BS6 norms by 70% in diesel engines and 25% in petrol engines.

  9. With the introduction of BS6 norms, both Selective Catalytic Reduction (SCR) and Diesel Particulate Filter (DPF) are used to regulate the emission levels, however, they were not part of BS4 norms.

  10. The Real Driving Emission (RDE) has been launched in BS6 norms to measure emission on a real-time basis. This was not the case with BS4 norms.

  11. Another mandatory addition in the BS6 norms is Onboard Diagnostic (OD), however, this was not mandated in the BS4 norms.

Frequently Asked Questions

 

Which is better: BS4 or BS6?

In comparison to the BS4, BS6 fuels emit less amount of sulphur and nitrous oxide. Hence, BS6 fuel is better than BS4 fuel.

The price for both BS4 and BS6 fuel are similar and there’s not much difference as of now. However, once the BS6 norms are implemented across the country, the prices may change in accordance with the input costs and upgrading facilities.

You can use a BS4 fuel to run the BS6 engine, however, the emissions, in this case, would not comply with the BS6 norms. To match the emission norms, it becomes important to use BS6 fuel and a BS6 engine.

Pollution under control (PUC) has been made mandatory for all types of vehicles including both BS4 and BS6 as per the Motor Vehicle Act.
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