Bharat Stage (BS) emission norms are India’s legally enforceable standards to limit air pollutants from motor vehicles, framed under the Motor Vehicles Act and aligned with European (Euro) norms.

  • Bharat Stage Emission Standards (BSES) regulate tailpipe emissions of carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), particulate matter (PM), and, in later stages, particulate number (PN).
  • They apply to compression-ignition (diesel) and spark-ignition (petrol/CNG) engines in two-wheelers, three-wheelers, cars, buses, trucks, and non-road equipment.
  • The standards are notified by the Ministry of Environment, Forest and Climate Change (MoEFCC) and implemented through the Central Pollution Control Board (CPCB)

Evolution of Bharat Stage Emission Norms

  • BS-I Norms
    • When: Introduced nationwide in 2000 (also called India 2000, aligned with Euro I).
    • What it did: Set India’s first pan-India limits on tailpipe pollutants—mainly CO, HC, NOx, and PM—for petrol and diesel vehicles.
  • BS-II Norms
    • When: 2001 in metro cities; expanded to more cities by 2003; nationwide by 2005.
    • Key Changes vs BS-I: Tighter limits on CO, HC, NOx, and PM; better engine calibration and fuel quality push.
  • BS-III Norms
    • When: 2005 in metros/major cities; nationwide by 2010.
    • Key Changes: Further reduction in NOx and PM; greater emphasis on on-board diagnostics (OBD) beginnings and better combustion control.
  • BS-IV Norms
    • When: 2010 in metros/major cities; nationwide from April 2017.
    • Key Changes: Significant cut in NOx and PM, especially for diesel; stronger OBD requirements; push for cleaner fuels (sulfur reduction).
  • BS-V Norms
    • Status: Skipped by policy decision; India moved directly from BS-IV to BS-VI.
  • BS-VI Norms
    • When: 2018 in Delhi; 2019 in NCR; nationwide from 1 April 2020.
    • Fuel Change: Sulfur in petrol/diesel cut from 50 ppm (BS-IV) to 10 ppm (BS-VI), enabling advanced after-treatment.

 

Source: The Hindu

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