Explained: Bharat Stage IV emission norms and the history behind it

How does BS-IV differ from BS-III and why are automobile manufacturers worried

In a move that is likely to have huge repercussions on the automobile industry, today, the Supreme Court banned the sale of Bharat Stage III vehicles with effect from April 1.The verdict came on pleas seeking a ban on sale and registration of BS III-compliant vehicles from April 1, when BS IV emission norms will come into force.

Centre had earlier backed auto manufacturers who said they had unsold stock of about 8 lakh vehicles that do not meet BS IV emission norms. The companies had suggested the government deadline for 1 April 2017 was for stopping manufacture of BS III vehicles, and not their registration.

Read: Supreme Court bans sale and registration of BS III vehicles from April 1

BS IV emission norms will come into effect from April 1, 2017. While most passenger vehicle makers have shifted to producing BS IV-compliant vehicles, two-wheeler, three-wheeler and commercial vehicle manufacturers were producing BS III vehicles with government notifying March 31, 2017 as the last date for manufacturing of such vehicles. 

What are Bharat stage emission standards?

Bharat stage emission standards'  are emission standards instituted by the Government of India to normalize the productivity of air pollutants from internal combustion engine equipment. The standards and the timeline for implementation are set by the Central Pollution Control Board under the Ministry of Environment & Forests and Climate Change. Bharat Stage norms are based on European regulations.

Difference between BS-III and BS-IV standards

BS norms are similar to Euro norms. According to a report of India Today, here is a comparison of the existing BS-III and BS-IV norms in India with the Euro 6 norms on which India's emission norms have been set.

Petrol Emission Norms (All figures in g/km)

Emission	Norm	CO	HC	NOx	HC+NOx	PM
BS-III	2.30	0.20	0.15	---	----
BS-IV	1.00	0.10	0.08	----	----
Euro 6	1.00	0.10	0.06	---	0.005

Diesel Emission Norms (All figures in g/km)

Emission	Norm	CO	HC	NOx	HC+NOx	PM
BS-III	0.64	----	0.50	0.56	0.05
BS-IV	0.50	----	0.25	0.30	0.025
eURO 6	0.50	----	0.06	0.17	0.005

(Note: Here CO emissions are Carbon Monoxide emissions and HC emissions stand for Hydrocarbons which are prevalent in Petrol engines. NOx is an acronym for Nitrogen Oxide emissions which exist in Diesel engines. PM stands for Particulate matter. )

History of Emission Norms in India

According to a report of Society of Indian Automobile Manufacturers (SIAM), the first emission norms were introduced in India in 1991 for petrol and 1992 for diesel vehicles.  Each stage specifies a certain limit on the pollutants released, which is controlled by the type of fuel made by the oil companies and the upgradations and modifications made by the auto firms to their vehicles to control the pollutants released from the vehicle.

Also read: Hurdle race begins for BS-VI switch

From April 1995, mandatory fitment of catalytic converters in new petrol passenger cars sold in the four metros, Delhi, Calcutta, Mumbai and Chennai along with supply of Unleaded Petrol (ULP) was affected. 

In the year 2000, passenger cars and commercial vehicles met  Euro I equivalent India 2000 norms. 

The first Auto Fuel Policy was announced in August 2002 which layed down the Emission and Fuel Roadmap upto 2010. 

Four-wheeled vehicles moved to Bharat Stage III emission norms in 13 metro cities from April 2005 and rest of the country moved to Bharat Stage II norms.

Bharat Stage IV for 13 Metro cities was implemented from April 2010 onwards and the rest of the country moved to Bharat Stage III. Bharat stage IV norms were extended to additional 20 cities from October 2014 onwards.

The new judgement

Supreme Court today banned the sale and registration of vehicles which are not compliant with BS-IV emission norms from April 1 across the country. The apex court observed that the "health of the people is more important than the commercial interest of automobile manufactures".

A bench of Justices Madan B Lokur and Deepak Gupta prohibited registration of any vehicles which do not meet the Bharat Stage-IV emission norm standards from April 1.

The Society of Indian Automobile Manufacturers (SIAM) had earlier submitted data on manufacturing and sale of BS-III vehicles on a monthly basis from January 2016 and told the court that the companies were holding stock of around 8.24 lakh such vehicles including 96,000 commercial vehicles, over six lakh two-wheelers and around 40,000 three-wheelers.