Why in news?

Recently, the Union Cabinet approved a two-year Clean Mobility Scheme for Delhi-NCR. The scheme will incentivise owners of older, more polluting trucks and buses to replace them with BS-VI or stricter emission-compliant vehicles.

It is expected to benefit owners of around 2.07 lakh vehicles — 1.91 lakh trucks and 16,329 buses. Government vehicles are excluded.

What’s in Today’s Article?

• Bharat Stage (BS) Emission Norms
• Why Old Trucks and Buses Are the Problem?
• Why Old Vehicles Are So Much Worse?
• What the Scheme Proposes?
• The Broader Pollution Context

Bharat Stage (BS) Emission Norms

• Bharat Stage (BS) standards are emission regulations set by the government to limit the amount of pollutants a vehicle's engine can release.
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• BS-VI is the current and strictest standard. It introduced tighter limits on pollutants, mandated cleaner fuels, and required advanced onboard diagnostic systems.
• India jumped directly from BS-IV to BS-VI in 2020, skipping BS-V entirely — a significant leap in emission control.

Why Old Trucks and Buses Are the Problem?

• Delhi-NCR has 2.98 crore registered vehicles, growing at 7% per year. The transport sector is one of the dominant sources of pollution — alongside dust, industrial emissions, and biomass burning.
• But not all vehicles pollute equally. Old trucks and buses are disproportionately responsible for a large share of the damage.
• The Numbers Tell the Story
  • Trucks and buses together account for 36% of PM2.5 emissions from the transport sector in Delhi-NCR.
    • PM2.5 refers to fine particulate matter — particles so tiny they penetrate deep into the lungs and enter the bloodstream, causing serious respiratory and cardiovascular disease.
  • A 2018 study by TERI found that the transport sector accounts for 40% of carbon monoxide and 63% of nitrogen oxide (NOx) emissions in Delhi-NCR.

Why Old Vehicles Are So Much Worse?

• A vehicle that is mechanically "fit" can still be dangerously polluting if it runs on an old BS standard.
• As engines age, parts wear out, combustion becomes incomplete, and emission controls degrade.
• Old vehicles also lack modern systems like diesel particulate filters and selective catalytic reduction that BS-VI vehicles use to clean exhaust.
• The pollution gap between old and new vehicles is staggering:
  • A pre-BS norm heavy-duty vehicle pollutes 14 times more than a BS-VI vehicle.
  • A BS-IV vehicle emits 2.7 times more than a BS-VI vehicle.
  • A 15-year-old legacy commercial vehicle emits 11 times more PM and 6 times more NOx than a modern BS-VI vehicle.
  • An old BS-I heavy-duty truck emits up to 35 times more PM than a new BS-VI vehicle.

What the Scheme Proposes?

• The scheme incentivises vehicle owners to voluntarily phase out their older trucks and buses and replace them with cleaner alternatives.
• The treatment differs by how old the vehicle is:
  • BS-III and older vehicles — Scrapping is mandatory.
  • BS-IV vehicles — Owners may either scrap them or sell them outside NCR, but only to areas not covered under the National Clean Air Programme (NCAP).
• This ensures that older polluting vehicles are not simply relocated from Delhi to other vulnerable cities.
• How This Fits Into India's Larger Clean Air Agenda?
  • This scheme does not stand alone. Several earlier initiatives have worked towards cleaner transport in Delhi-NCR — the PM-eBus Sewa scheme for electric buses being a prominent example.
  • The National Clean Air Programme (NCAP), launched in 2019, targets a 40% reduction in PM2.5 and PM10 concentrations by 2026 in 131 non-attainment cities — cities that consistently fail to meet air quality standards.
  • The Clean Mobility Scheme complements these by specifically addressing the legacy vehicle problem.

The Broader Pollution Context

• Delhi-NCR's air pollution is driven by multiple sources — transport, construction dust, industries, and seasonal factors like crop stubble burning and winter weather conditions.
• Meteorology matters too. Cold, still winter air traps pollutants near the ground, which is why Delhi's pollution peaks in November and December.
• The Commission for Air Quality Management (CAQM) — a statutory body set up specifically for Delhi-NCR air quality — has been monitoring these sources and directing action.
• In data submitted to the Supreme Court in December 2025, CAQM confirmed that of the 1.61 lakh buses in Delhi-NCR, only 34,449 are BS-VI compliant — the rest, over 1.26 lakh buses, fall in the pre-BS to BS-IV category. This is a massive backlog of dirty vehicles.