Bharat Stage Emission Norms

Bharat Stage emission norms are legally prescribed limits on air pollutants released by motor vehicles and their engines in India. Their purpose is to reduce harmful vehicular pollution through progressively cleaner engines, emission-control technologies and fuels. They are broadly aligned with European emission standards but adapted to Indian requirements.

Pollutants controlled and purpose

The norms address pollutants that directly degrade local air quality and harm human health. They primarily limit carbon monoxide, hydrocarbons, nitrogen oxides and particulate matter, with applicable limits varying by vehicle and fuel type.

• Successively stricter stages compel manufacturers to use cleaner combustion systems and technologies such as catalytic converters, particulate filters and selective catalytic reduction.
• Bharat Stage norms principally regulate conventional air pollutants; vehicle fuel-efficiency and carbon dioxide requirements are governed separately.

How the norms operate

Vehicle emission limits are prescribed under Rule 115 of the Central Motor Vehicles Rules, 1989. Compliance is enforced through type approval and conformity-of-production requirements, while corresponding fuel-quality improvements enable advanced emission-control systems to function effectively.

• The norms follow a coordinated vehicle-and-fuel approach because high-sulphur fuel can impair emission-control equipment.
• Under BS VI, sulphur in petrol and diesel was reduced to 10 parts per million, compared with 50 parts per million under BS IV.
• BS VI also strengthened testing requirements and introduced more advanced onboard diagnostics and emission-control provisions.

Progression in India

India introduced progressively tighter stages beginning with India 2000 norms. BS IV became applicable nationwide in 2017, while BS VI took effect nationwide from 1 April 2020, with BS V being skipped.

• The progression reduces emissions from new vehicles and encourages technological upgrading by automobile manufacturers and petroleum refineries.
• The standards do not by themselves eliminate pollution from older vehicles, traffic congestion, poor maintenance or non-vehicular sources.