Bharat Stage Six (BS6) | Bharat Stage Emission Standards.

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Rapid and continuous increase in industrialization and transport vehicles results in a massive increment in air pollutants.

Bharat Stage Six, (BS6), Bharat Stage Emission Standards.
Bharat Stage Six (BS6) 

Increased air pollution harming human health. Air pollution causes Cardiovascular and Respiratory diseases in humans. According to research conducted, nearly 6,20,000 people died in the year 2010 because of respiratory and cardiovascular diseases. This is a huge number. If air pollution increases rapidly, it will be very dangerous for all human beings living on the earth.

It is very much necessary to take action towards controlling air pollution within a moderate or acceptable range. To control the pollution within the acceptable range, actions were started to be taken from the year 2000.

European regulations were followed during the starting stage of emission control. Later on rules. and regulations become stringent and introduce changes in emission norms progressively.

The government of India also put forward to take action against the emission of pollutants. In India, the third iteration of pollution control named Bharat Stage 3 (BS3) was implemented in the year 2010. The first two iterations of pollution controls were based on European Regulations.

With the change in pollution levels, it is necessary to implement a modified version of Emission Standards. That’s the reason, now we are in the 6th iteration (BS6)  of pollution control standards. According to that, the modified version of BS3 i.e. BS4 came into existence from Apr 2010 But it was enforced from Apr 2017. This huge delay between the implementations of BS3 and BS4 vehicles leads to the rapid implementation of BS6 instead of BS5.


The Government of India Banned the registration and sales of BS4 vehicles w.e.f. 1 Apr 2020. BS5 was skipped in the year 2016 and instead, BS6 was enforced w.e.f. 1 Apr 2020. The petroleum ministry of India decided to implement the BS6 in NCT Delhi in the year 1 Apr 2018 instead of 1 Apr 2020, because of the tremendous increment in air pollution in the NCT Delhi region.

Technological Changes in Petrol Engine for the 6th iteration (BS6) of emission standards.

In BS6, the emission of Carbon Monoxide is reduced by 30% and nitrogen Oxide by 80%. Limitations for the emission of hydrocarbons and particulate emissions are also set in BS6 But not mentioned in early norms.

Petrol Engine modifications for BS6 

  • The carburetor is replaced by Programmed Fuel Injectors to meet emission requirements.
  • An exhaust system fitted with a 3-way catalytic converter reduces tailpipe emissions. 
  • Mandatory implementation of On-board Diagnostic (OBD) System for the identification of faults and malfunctioning.

Technological Changes in Diesel Engine for the 6th iteration (BS6) of emission.

In BS6 nitrogen oxide, NOx emission is reduced by 70% and particulates emission by 80%.

Diesel Engine modifications for BS6 

BS6 Diesel engines equipped with Euro – 6 complaint Technologies. 

Euro – 6 Complaint Technologies consists of 


  • Diesel pre-filters fitted in the exhaust.
  • Selective Catalytic Reduction system is used or alternative method i.e. Exhaust Gas Recirculation Technology is used for the reduction of nitrogen oxides ox.


To meet the required emission requirement the quality of fuel plays an important role. In India, BS4 fuels were introduced in 39 cities till the end of 2016 and the rest of the cities remain with BS3 fuels.

The Indian automobile sector introduced alternative fuels for the reduction of emissions and energy security. In Delhi and Mumbai over 100,000 commercial vehicles runs on CNG

India automobile sector planning for introducing BioDiesel and ethanol petrol blends as an alternative fuel. Also set for the hydrogen fuel road map.

LPG is also used as fuel in various commercial vehicles. Auto fuel and oil industry plans for “Auto LPG Dispensing Stations.

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