India: Heavy-duty: Emissions


Bharat Stage (BS) IV standards (based on Euro IV) applied to all new vehicles nationwide in April 2017. BS VI standards (based on Euro VI) standards, which apply in April 2020, establish an important precedent for leapfrogging from Euro IV-equivalent directly to Euro VI-equivalent standards.

Standard type
Conventional pollutant emission limits
Regulatory Body

The body that is primarily responsible for setting emissions and efficiency standards is the Ministry of Road Transport and Highways (MoRTH). Further detail regarding India’s regulatory bodies can be found on the India Regulatory Background page. Other regulatory agencies responsible for fuel and environmental regulations are below.

Vehicles with Gross Vehicle Weight (GVW) > 3,500 kg including commercial trucks, buses, and on-road vocational vehicles such as refuse haulers and cement mixers


Starting with court rulings in the late 1980s and 1990s, India began to lower its permissible vehicular pollution emission limits for four-wheelers. Beginning in 2000, India followed the ‘Euro’ pathway, adopting parallel ‘Bharat’ standards (e.g. Bharat III standards are equivalent to Euro III standards). New vehicles sold in nearly half of the country must meet Bharat Stage IV (Euro IV) standards, while the rest meet Bharat Stage III standards.

Important legislative milestones include:

The Auto Fuel Policy of 2003 set a roadmap for progressively tighter heavy-duty vehicle emission standards through 2010, which is currently still in force. This policy aligned Indian emission standards with the European model.

The Auto Fuel Policy of 2003 also laid out two different sets of standards, one for advanced cities and one for the rest of the country. In the case of heavy-duty vehicles, this incongruity has resulted in few trucks meeting the tougher emissions standards of advanced cities, since they are sold and registered in outside areas.

The following table shows the advanced implementation timeline in India’s main cities.

Advanced Implementation of HDV Emissions Standards in India’s Main Cities

India emission standards timeline.png

a – Proposed implementation date
b – 24 Oct 2000 for Delhi; 21 Oct 2001 for Mumbai, Kolkata and Chennai

Bharat Stage VI

On 19 Feb 2016, the Ministry of Road Transport and Highways (MoRTH) issued a draft notification of Bharat Stage (BS) VI emission standards. The standards, as proposed, will take effect throughout the country for all light-duty and heavy-duty vehicles as well as two and three wheelers manufactured on or after 1 Apr 2020. The draft proposal specifies mass emission standards, type approval requirements, and on-board diagnostic (OBD) system and durability levels for each vehicle category. Additional provisions in the draft proposal include:

  • Adoption of more stringent WHSC and WHTC test cycles
  • Off-cycle emissions testing requirements and in-service conformity testing for type approval
  • Specifications for PEMS demonstration testing at type approval

The proposed BS VI regulation establishes an important precedent for leapfrogging from Euro IV-equivalent directly to Euro VI-equivalent motor vehicle emissions standards.

Technical Standards

Emission Standards

Prior to 2010, emissions were tested using the ECE R49 test cycle. After 2010, for Bharat III and IV, the ESC and ETC test cycles were used. BS VI will require the application of WHSC and WHTC test cycles. Standards for new heavy-duty engines are listed below.

Emission Standards for Heavy-Duty Vehicles and Engines
Year Reference Test CO HC CH4 NOx PM PN
g/kWh #/kWh
1992 ECE R49 17.3-32.6 2.7-3.7
1996 ECE R49 11.20 2.40 14.4
2000 Bharat Stage I ECE R49 4.5 1.1 8.0 0.36*
2005† Bharat Stage IIa ECE R49 4.0 1.1 7.0 0.15
2010 Bharat Stage IIIb ESC 2.1 0.66 5.0 0.10/0.13d
ETC 5.45 0.78 5.0 0.16/0.221d
2010 Bharat Stage IVc ESC 1.5 0.46 3.5 0.02
ETC 4.0 0.55 3.5 0.03
2020 Bharat Stage VIe WHSC(CI) 1.5 0.13 0.40 0.01 8x1011
WHTC(CI) 4.0 0.16 0.46 0.01 6x1011
WHTC(PI) 4.0 0.16f 0.5 0.46 0.01 6x1011
* 0.612 for engines below 85 kW
† Test cycle changes from ECE R49 to ESC & ETC
a – From 24 Oct 2001 in Delhi; 31 Oct 2001 in Mumbai, Kolkata and Chennai; 1 Apr 2003 in Bangalore, Hyderabad, Ahmedabad, Pune, Surat, Kanpur and Agra; and 1 Apr 2005 in the rest of the country.
b – From 1 Apr 2005 in Delhi, Mumbai, Kolkata, Chennai, Bangalore, Hyderabad, Ahmedabad, Pune, Surat, Kanpur, Solapur, Lucknow, and Agra; and 1 Apr 2010 in the rest of the country.
c – From 1 Apr 2010 in Delhi, Mumbai, Kolkata, Chennai, Bangalore, Hyderabad, Ahmedabad, Pune, Surat, Kanpur, Solapur, Lucknow, and Agra. As of April 2016, applicable in 10 states, different districts & cities in the states of Rajasthan, Maharashtra, Gujarat and Uttar Pradesh and in 4 Union Territories. Nationwide implementation in April 2017.
d – For engines with swept vol. <0.75 liter per cylinder and rated power speed >3000 rpm
e – Proposed limits
f – NMHC for PI engines

The BS VI standard also includes a limit for ammonia emissions, which should not exceed 10 ppm for compression ignition as well as positive ignition engines.


Heavy-duty vehicle emissions are certified in two phases. First, the engine (including the emission control system) is tested on an engine dynamometer. Then the vehicle impacts are incorporated by reference, which requires using other test data and engineering judgment to establish how the remainder of the vehicle’s components would impact engine emissions.1 Engine emission limits are specified in grams per kilowatt-hour.

Unlike Indian light-duty vehicles, which are tested using chassis dynamometer testing, heavy-duty vehicle emissions are certified using two cycles performed on an engine dynamometer: the European Stationary Cycle (ESC) and the European Transient Cycle (ETC). Diesel-operated HDVs must pass both tests to be certified. HDVs operating on CNG do not have to undergo the ESC test.

The proposed BS VI regulation would replace ESC and ETC with WHSC and WHTC, respectively. Further, the regulation proposes the adoption of World Harmonized Not-to-Exceed (WNTE) off-cycle laboratory testing following UNECE Regulation No-49. Specifications for PEMS demonstration testing at type approval are also included in the BS VI regulation. Specific procedures regarding these requirements will be defined in the AIS 137 implementing standard.

Test Fuels Under Bharat III and IV specifications, fuel used to test emissions from vehicles is cleaner than commercially available fuel. Regulations specify that Bharat IV test diesel can have a maximum sulfur content of 10 ppm, while commercial diesel contains up to 50 ppm and 350 ppm sulfur in Bharat IV cities and the rest of the country, respectively. The lower sulfur content in test fuel means emissions measurements during testing are lower than real-world emissions on the road, particularly for particulate matter (PM). The full diesel and petrol specifications for test fuels may be found in the ARAI Indian Emission Regulation Booklet.

The BS VI standard specifies a maximum of 10 ppm sulfur for reference gasoline and diesel fuels. The Ministry of Petroleum and Natural Gas (MoPNG) announced nationwide supply of BS VI fuel in conjunction with the proposed BS VI emission standard implementation date of 1 Apr 2020. For details on fuel specifications for BS VI, see India: Fuels: Diesel and Gasoline.3.3 OBD Requirements

The proposed BS VI standard specifies OBD requirements for all major on-road vehicle categories in India. For heavy-duty vehicles, the draft proposes introduction of OBD in two stages: BS VI-1 and BS VI-2. BS VI-1 OBD will apply to new type approvals on 1 Apr 2020 and all sales and registrations on 1 Apr 2021, and BS VI-2 OBD will apply to all sales and registrations beginning 1 Apr 2023. Threshold values for BS VI-1 OBD and BS VI-2 OBD follow preliminary and final Euro VI threshold limits, respectively. Full specifications for BS VI OBD systems will be included in AIS 137. The threshold values for BS VI-1 and BS VI-2 OBD systems are listed in the table below.

OBD Threshold Limits, g/kWh
Stage Implementation Date Engine Category CO NOx PM
BS VI-1 1 Apr 2020 (type approvals)
1 Apr 2021 (all sales)
Compression Ignition 1.5 Performance Monitoring *
Positive Ignition 1.5
BS VI-2 1 Apr 2023 (all sales) Compression Ignition 1.2 0.025
Positive Ignition 7.5 1.2
* Performance monitoring as per AIS-137 (for wall–flow Diesel Particulate Filter)


BS VI follows Euro VI specifications for the durability of pollution control devices. Manufacturers may either use deterioration factors specified in the standard or evaluate deterioration factors by service accumulation. Minimum service accumulation mileages for different vehicle categories are listed in the following table.

Minimum Service Accumulation Mileages
Vehicle Category Mileage
N1 and M2 160,000 km
N3 (GVW≤ 16 ton)
M3 (GVW≤ 7.5 ton)
188,000 km
N3 (GVW> 16 ton)
M3 (GVW> 7.5 ton)
233,000 km

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