As the National Capital Region prepares to come to terms with The National Green Tribunal's (NGT) order of banning diesel vehicles more than 10 years old from plying in the NCR - the Tribunal has stayed its own order for two weeks - it has been hailed as a welcome step by environmental activists.
Hem H. Dholakia, Research Associate at CEEW (Council on Energy, Environment and Water) said that the World Health Organization has found sufficient evidence that diesel vehicular exhaust is carcinogenic to humans. "In light of this, banning diesel vehicles more than 10 years vintage is a step in the right direction," says Dholakia. "This will translate into roughly 150,000 vehicles being retired each year."
Sumit Sharma, Fellow & Area Convenor, Centre for Environmental Studies (CSE), TERI pointed out that this is an appreciable move to reduce air pollutant emissions in a short time frame.
"Diesel vehicles always had higher shares in the emission inventories. While the newer vehicles (Euro-III/IV) are equipped with better technologies which result in lower emissions, the older vehicles emit many times higher."
Sharma says that while buses in Delhi have moved to CNG, inter-state buses, trucks and cars still ply on diesel.
Merely not allowing trucks into the city in daytime does not help, especially in the winter season when the heavy smog caused by pollution does not disperse due to meteorological factors.
Diesel vehicle exhausts have also been identified as carcinogens by the WHO and it makes perfect sense for their reduction.
However, experts felt that the immediate removal of old diesel vehicles may create practical problems.
A more gradual approach in a limited time-frame could be adopted to modernise the fleets.
Anumita Roychowdhury, Head of the Air Pollution Team at CSE, told BT that in principle it is accepted that retirement of grossly polluting vehicles can substantially reduce pollution load.
However, this sudden ban has come as a knee jerk reaction largely to counter the policy inertia in the capital to address the killer pollution.
"Instead of a drastic ban, the city can adopt a time-bound phase-out plan for very old vehicles. As it is done in other parts of the world, the older vehicles can be colour coded for easy recognition. Either registered within or outside Delhi, they need to be labelled."
She recommended that this colour code can reflect the technology vintage like pre-Euro I and Euro I and II and these can be barred in phases. Simultaneously, introduce annual registration tax on all vehicles and increase the tax rate according to age.
This will disincentivise the older vehicles. "The revenue from this tax can be taken to a public transport fund. A onetime grant can also be made for replacement of these vehicles only with vehicles meeting Euro V emissions standards and above."
Aishwarya Madineni, campaigner, Climate and Energy Team, Greenpeace India, said that that the move by NGT does signify the urgency of the situation in the national capital.
"However, this move in itself is not going to be a solution to the problem. The answer lies in regulation-an increased investment in the public transport system along with improved fuel quality is a must. Stricter emission standards for the vehicular exhausts and industries need to be in place immediately."