Delhi bans non-BS VI vehicles from outside: Why curbing vehicular pollution is key

More than a third – around 37% – of this fleet comprises Bharat Stage (BS) III or even older vehicles, which have a significantly higher emissions potential.

BS-III and older diesel vehicles emit between 2.5 and 31 times more particulate matter, 6.25 to 12 times more nitrogen oxides, and 1.28 to 5.4 times more carbon monoxide compared to newer vehicles, according to CAQM estimates.

Petrol vehicles of BS-III and earlier vintage emit 2.5 to 16 times more nitrogen dioxide and 2.3 to 2.72 times more carbon monoxide.

Rajeev Mishra, associate professor at Delhi Technological University, who has carried out extensive research on vehicular pollution, told The Indian Express, “Studies have shown that vehicles contribute around 40% to Delhi’s PM2.5 load. It is clear that the focus should be on cutting emissions.”

Mishra pointed out that policy attention often disproportionately targets cars. “The fleet contribution by two-wheelers is very high… so not only four-wheelers, there has to be focus on tackling tailpipe emissions,” he said.

Amit Bhatt, Managing Director (India) at the International Council on Clean Transportation (ICCT) and a member of the CAQM’s expert committee on vehicular pollution, said, “If you look at cities that have cleaned their air, they have all moved towards a zero-emissions vehicle future. Be it Beijing or San Francisco…you cannot clean Delhi’s air without cleaning up transport.”

… And with the policy

PUC REGIME: Bhatt said that the current pollution-under-control (PUC) regime is structurally not up to tackling the task at hand.

“Our current regime of PUC, which certifies vehicles to be clean or not, doesn’t measure particulate matter emissions. So, we don’t know what is coming out from the vehicle because we are not even measuring it,” Bhatt said.

A study conducted by ICCT last year found that real-world emissions from pre-BS VI vehicles were far higher than laboratory values, including for CNG vehicles. “These are actual emissions – what vehicles emit when they are driven,” Bhatt said.

ENFORCEMENT: Poor enforcement is a major problem, Mishra said. “More than half the vehicles on Delhi’s roads don’t have PUCC. There is now an effort to force vehicle owners to get PUCC, but there is no talk about prominent pollutants… there are no guidelines for PM2.5,” he said.

VEHICLE POPULATION: The massive increase in the number of vehicles has undermined the gains from tighter emissions standards. In this, Delhi stands out – its vehicular population is more than that of several other metros combined.

“Post-pandemic, vehicle registrations across the country grew by almost 7.5% per year. But in Delhi, it grew by 8.7% per year,” Bhatt said. “If vehicle numbers keep increasing, absolute pollution will also increase, no matter how efficient we make these vehicles.”

Environmentalists such as Bharati Chaturvedi of Chintan have flagged demand-side controls, arguing that restrictions on large social events may be necessary during high-pollution periods as they sharply increase vehicle movement.

STRUCTURAL REFORMS: Sunil Dahiya, founder and lead analyst at Envirocatalysts, pointed to the policy inconsistency on age-based bans on vehicles.

“A few months back, the Delhi government said we cannot ban vehicles based on their age. Now they are saying we will ban non-BS-VI-compliant vehicles, which is basically an age-based criteria because BS-VI was introduced in 2017,” Dahiya said.

Partial measures, unless paired with structural reforms, will deliver limited results, Dahiya said. “To gain from such interventions, utilising the scrappage policy and strengthening of public transportation should go hand in hand,” he said.

Experts have also criticised Delhi’s reactive, winter-only approach. Mishra said, “Once it’s February the action will also be relaxed. We need a control mechanism that functions round the year and is not reactive. This should be at the ward level.”

Also, pollution does not respect administrative boundaries, and Delhi and NCR cities such as Gurgaon and Noida function as a single urban airshed.

“This is one large urban agglomeration,” Bhatt said. “If we have to solve the problem of Delhi, we also have to not only take action in Delhi, but also in the greater region of Delhi.”