Maarg Manthan · Topic 13.10

Bharat Stage Emission Norms

Environment & Ecology › Air, Marine, Noise and Other Pollution · Topic 13.10

Bharat Stage (BS) emission norms are the standards set by the Government of India to limit the air pollutants released from the exhaust of motor vehicles and engines, modelled on the European (Euro) norms. They are framed by the Central Pollution Control Board and notified by the Ministry of Road Transport and Highways under the Central Motor Vehicles Rules, 1989, with the Ministry of Petroleum and Natural Gas supplying matching cleaner fuel. India started with Bharat Stage I in 2000 (equal to Euro I), followed by BS-II (2001, with some cities earlier), BS-III (2005 in selected cities, nationwide in 2010) and BS-IV (2010 in selected cities, nationwide in April 2017). India skipped BS-V and moved directly to BS-VI from 1 April 2020, with Delhi adopting it in April 2018. BS-VI fuel has a maximum sulphur content of 10 parts per million against 50 ppm in BS-IV, and the norms cut particulate matter from diesel cars by about 80 percent and nitrogen oxides from diesel cars by about 70 percent. Real driving emission tests were added in a second phase from April 2023.

5 min read · UPSC Prelims · Environment & Ecology · Air, Marine, Noise and Other Pollution

At a Glance

Based on Euro norms
First stage BS-I, 2000
BS-IV nationwide April 2017
BS-VI 1 April 2020
Sulphur in BS-VI fuel 10 ppm
Exam link UPSC Prelims, Environment & Ecology: Air, Marine, Noise and Other Pollution

Where Does It Fit?

This topic follows the account of particles and applies to vehicle emissions, a major source of urban air pollution. It leads to air quality indices and the pollution index for industrial areas. Previous topic: Respirable Suspended Particulate Matter (RSPM) and Fly Ash. Next topic: National Air Quality Index and Comprehensive Environmental Pollution Index.

How Did Bharat Stage Norms Evolve?

Stage	Timeline and features
BS-I	Introduced 2000 nationwide, equivalent to Euro I
BS-II	2001 in Delhi and major cities, nationwide by 2005
BS-III	2005 in 11 cities, nationwide in 2010
BS-IV	2010 in 13 cities, nationwide on 1 April 2017; sulphur in fuel 50 ppm
BS-V	Skipped; planned for 2019 but India went straight to BS-VI
BS-VI	Delhi from April 2018; nationwide from 1 April 2020; sulphur 10 ppm; equal to Euro VI
BS-VI Phase 2	From April 2023; real driving emission testing, on-board diagnostics and monitoring of emissions

What Technology and Benefits Come with BS-VI?

Cleaner fuel: 10 ppm sulphur fuel lets advanced exhaust devices work
Diesel particulate filter: traps soot from diesel engines
Selective catalytic reduction: uses urea (AdBlue) to convert NOx to nitrogen
Three-way catalytic converter: for petrol engines
Lower emissions: large cuts in particles and NOx from diesel vehicles
Cost: higher vehicle prices and need for refinery upgrades
Old vehicles: older BS-III or BS-IV vehicles stay on roads and pollute more
Beyond: a push to electric vehicles and in-use checks, scrappage policy

What Else Should You Remember?

Euro norms: European emission standards that Bharat Stage follows with a time lag
CPCB role: suggests standards and monitors compliance
MoRTH: Ministry of Road Transport and Highways notifies the norms
Central Motor Vehicles Rules, 1989: the legal basis for vehicle standards
Auto Fuel Policy 2003: a roadmap under the Mashelkar Committee that proposed the Bharat Stage timeline
Mashelkar Committee: headed by R A Mashelkar, which made the 2002 report
Pollutants regulated: carbon monoxide, hydrocarbons, nitrogen oxides and particulate matter
Sulphur in diesel: in BS-III was 350 ppm, in BS-IV 50 ppm and in BS-VI 10 ppm
Fuel quality: matched supply of BS-VI petrol and diesel across India from April 2020
Skipping BS-V: done to speed up improvement in air quality, mainly after Delhi’s air crisis
Cost of leap: oil refiners invested heavily to upgrade refineries
Real driving emissions: test on the road, not just in a lab, to check real emissions
OBD: on-board diagnostics that warn of faults in emission controls
Pollution Under Control certificate: periodic emission check for vehicles in use
Vehicle scrappage policy: 2021 policy to remove old, polluting vehicles
Fitness test: old vehicles need periodic fitness tests at automated centres
Two and three wheelers: also follow BS-VI norms
Diesel vehicles: contribute high NOx and particles, so standards are stricter
Trucks and buses: heavy vehicles are a large source of NOx
CNG vehicles: emit fewer particles
Electric vehicles: have no tailpipe emissions
Supreme Court role: orders in the 1990s on CNG in Delhi buses and later on the BS-IV to BS-VI shift
Link to previous: see Respirable Suspended Particulate Matter (RSPM) and Fly Ash
Link to next: see National Air Quality Index and Comprehensive Environmental Pollution Index
Link to electric vehicles: see National Electric Mobility Mission Plan
Caution: dates differ by city and vehicle type, so check the notification for exact schedules
Exam hint: learn BS-I 2000, BS-IV 2017, BS-VI 2020 and that BS-V was skipped
Sulphur content: diesel sulphur fell from 350 ppm in BS-III to 50 ppm in BS-IV and 10 ppm in BS-VI, which also cut SO2 and sulphate particles
Central Motor Vehicles Rules: the vehicle emission standards are prescribed under these rules, with test procedures approved by agencies like ARAI and ICAT
Type approval: each new vehicle model must be tested and approved before sale
Particulate number limit: BS-VI added a limit on the number of particles from petrol direct injection engines
Heavy-duty engines: trucks and buses have their own BS-VI standards, with transient and steady tests

Why Does It Matter for the Exam?

First: BS-I, 2000
Skipped: BS-V
Current: BS-VI, 2020
Current affairs link: Scrappage and EVs
Common errors: saying BS norms are set under the Air Act

As an analytical point, cleaner engines work only with cleaner fuel and regular checks. The jump to BS-VI cut tailpipe pollution from new vehicles, but old vehicles and rising numbers of vehicles can cancel the gains.

Why Is This Topic Important?

Aim Cut exhaust
Needs Cleaner fuel
Gap Old vehicles

What Came Next?

The next topic covers the National Air Quality Index and the Comprehensive Environmental Pollution Index. Next topic: National Air Quality Index and Comprehensive Environmental Pollution Index.

Key People and Terms

BS Bharat Stage
DPF Diesel particulate filter
SCR Selective catalytic reduction
RDE Real driving emissions
OBD On-board diagnostics
PUC Pollution Under Control certificate

Exam Corner

Points to Remember

BS-I in 2000.
BS-IV nationwide in 2017.
BS-V skipped.
BS-VI from 1 April 2020.
Sulphur: 10 ppm.

Do Not Confuse With

BS norms and Euro norms Indian versus European standards
BS-IV and BS-VI 50 ppm versus 10 ppm sulphur fuel
DPF and SCR Particle filter versus NOx converter

Memory Hook

Two thousand one, seventeen four, twenty six; five was skipped.

Mains Angle

Questions ask for stages, dates and technology. These points help.

Stages BS-I to VI
Tech DPF, SCR
Gaps Old vehicles

A Question You May Face

An original practice question, not a past paper question.

“Explain the Bharat Stage emission norms and assess their contribution to controlling vehicular pollution in India.”

How to Answer

Define BS norms.
Timeline I to VI.
Tech DPF.
Gaps Old fleet.

GS Relevance

Prelims: BS stages, dates, differences. GS Paper 3: vehicle pollution control.

Frequently Asked Questions

What are Bharat Stage emission norms?

Bharat Stage emission norms are standards set by the Government of India to limit the amount of pollutants such as carbon monoxide, hydrocarbons, nitrogen oxides and particulate matter released from the exhaust of motor vehicles and engines. They follow the European Euro norms with a time lag and are notified by the Ministry of Road Transport and Highways.

When did India move to BS-VI?

India moved to BS-VI from 1 April 2020, skipping BS-V entirely. Delhi had adopted BS-VI fuel in April 2018. BS-VI is equal to Euro VI and requires fuel with only 10 parts per million of sulphur, and vehicles with devices like diesel particulate filters and selective catalytic reduction.

Why did India skip BS-V?

India skipped BS-V to speed up improvement in air quality, because of severe pollution in Delhi and other cities and because moving directly from BS-IV to BS-VI avoided a costly intermediate step for refiners and carmakers. The change required major refinery upgrades and vehicle redesign, completed within about two years.

How much cleaner is BS-VI than BS-IV?

BS-VI fuel has 10 ppm sulphur against 50 ppm in BS-IV. For diesel cars, BS-VI norms cut particulate emissions by about 80 percent and nitrogen oxides by about 70 percent compared with BS-IV, and for petrol cars NOx limits are about 25 percent lower, with stricter tests including real driving emissions in the second phase.

Which technologies are used to meet BS-VI?

Petrol vehicles use improved three-way catalytic converters and fuel injection. Diesel vehicles need diesel particulate filters to trap soot and selective catalytic reduction, which uses a urea solution to convert nitrogen oxides to nitrogen. On-board diagnostics and cleaner low-sulphur fuel are also required.

PYQ Practice — Statement Analysis

1 India skipped BS-V and moved to BS-VI.

True

In April 2020.

2 BS-VI fuel has 50 ppm of sulphur.

False

It has 10 ppm.

3 BS norms are based on Euro norms.