A key challenge is meeting the transport demand which was previously catered to by the phased-out vehicles.
Gufran Beig
Mar 13, 2025 07:04 IST First published on: Mar 13, 2025 at 07:04 IST
Delhi has been ranked the world’s most polluted capital for the sixth year in IQAir’s 2024 World Air Quality Report. While short-term measures like GRAP cause temporary improvement, they are not permanent fixes for the capital’s problems. The newly installed Delhi government’s announcement banning the refuelling of vehicles older than 15 years from March 31 offers a glimmer of hope for lasting air quality improvement if implemented diligently. Over the last few years, we have often been inundated with fanciful ideas from the realm of geoengineering. These ideas were neither rooted in sound science nor designed as a long-term solution.
In recent years, other high-stakes ideas have also been mooted. One such quick fix was installing “smog towers” to clean air. This is like fixing an air conditioner in an infinite open space and expecting pleasant cooling in the scorching heat. Latest research by scientists at the National Institute of Advanced Studies (NIAS), using complex numerical models, reveals that air pollution plateaus and levels off just 150-200 meters from a smog tower. The tower can purify only 0.00007 per cent of the air every hour. Given these figures, Delhi would require 48,000 such towers to make an impact — an impractical proposition. Cloud seeding is another questionable solution. As its name suggests, the technique is about seeding specific types of clouds — especially cumulus or stratus — which contain enough moisture to produce rain. Winters are often marked by the absence of these clouds. So what will we be seeding during this season?
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If we truly want to address the underlying structural issues of air quality, we need to rip off band-aids and confront the root causes head-on, namely, “targeting emissions at source”. In this context, a scientific analysis of the efficacy and benefit of the new intervention — the 15-year-old vehicle ban — implemented to the T, would be worth discussing, According to a recent research and policy brief by NIAS, a complete phase-out of 15-year-old vehicles in Delhi would result in the decommissioning of over 5.7 million vehicles, which account for 46 per cent of the city’s transport fleet. Removing these vehicles from the roads could lead to an estimated ~28 per cent reduction in toxic PM 2.5 pollution, along with substantial health and economic benefits. This includes an annual saving of Rs 1,740 crore from reduced mortality and morbidity, as well as per capita healthcare savings of Rs 1,202. However, the implementation of this policy requires meticulous planning and diligence.
A key challenge is meeting the transport demand which was previously catered to by the phased-out vehicles. To maintain air quality benefits, the replacement vehicles should ideally be electric (EVs). This transition comes with its own set of challenges, including the need for adequate charging infrastructure, battery advancements, tire technology improvements, increased power supply, and access to raw materials. Alternatively, if the phased-out vehicles are replaced with newer BS-VI-compliant vehicles instead of EVs, PM 2.5 levels would still see a significant reduction of 19 per cent with significant healthcare cost savings. However, this would not be a permanent solution. While every innovative policy comes with challenges, addressing them with rigour is essential for successful implementation and long-term sustainability.
It is essential to communicate with the owners of the vehicles which the government proposes to scrap to help them understand the policy’s long-term benefits. While emissions from a vehicle depend on how well it has been maintained, they are significantly influenced by age. Older engines deteriorate over time causing an increase in emissions. Emissions also vary based on the vehicle’s make, model, fitness, and kilometres travelled (VKT). A few years ago, a comprehensive survey by SAFAR of the Ministry of Earth Sciences led to the development of a high-resolution (400m) gridded emission inventory for Delhi which revealed that ~30 per cent of vehicles operating in Delhi originate from other states. Therefore, the enforcement mechanism should incorporate detection technology to ensure that vehicles older than 15 years do not operate in the region.
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The question, however, remains: What region should this policy apply to? Air pollution is agnostic to human-made political borders. Banning vehicles in Delhi alone will not prevent emissions from affecting its air quality if older vehicles continue to operate in nearby areas. NIAS has launched the National Air Quality Resource Framework of India (NARFI) under the aegis of the Office of the Principal Scientific Advisor to the Government of India. This initiative mapped 16 airsheds across India, including the Delhi airshed, which spans parts of six surrounding states. To be effective, the 15-year vehicle ban policy must consider the entire Delhi airshed when designing interventions, rather than being limited to select administrative boundaries. Pollution follows airshed dynamics. The sooner we understand it, the closer we shall be to devising effective solutions. It is, therefore, imperative to transcend regional borders and work on a comprehensive strategy to address the entire Delhi airshed. Our breath may just depend on it.
The writer is chair professor NIAS Bengaluru and founder director, SAFAR
