NEW DELHI: In an order that could improve Delhi's deteriorating air quality if implemented effectively, the National Green Tribunal on Tuesday prohibited diesel vehicles that are over 10 years old from plying in the capital. A five-member bench, headed by NGT chairperson Swatanter Kumar, said that while such vehicles would be phased out in Delhi, those coming from other states would not be allowed to enter the city.

The order follows a similar one passed by NGT in November last year that had banned all vehicles over 15 years old from plying in Delhi. For various reasons, the government failed to implement that order. Sources said the higher emissions by diesel vehicles compared to petrol ones and the lax quality and emission standards prompted the bench to take a stern view. The order comes into effect immediately though enforcement may take a while to start.

Reacting to the order, Delhi environment minister Asim Ahmed Khan asked the Centre to impose a "hefty fine" on vehicles that are 15 years old or more.

The bench also directed the government and various agencies concerned to ensure that inter-state vehicles that flouted pollution norms or were diesel vehicles older than 10 years were not allowed into Delhi. For this, a 20-hour deadline was given for installing weighbridges and setting up pollution-under-control centres and also for devising a mechanism to determine the age of the vehicle. The court has appointed local commissioners to inspect the entry points and present a report to the court on April 10, the next date of hearing.

The order is expected to impact 1,18,773 private vehicles and 34,659 commercial vehicles in the city. Besides, more than 5 lakh vehicles enter Delhi every day of which around 50,000-75,000 are trucks and about 2,500 are state transport buses. All these run on diesel and are likely to run into trouble.

However, implementation of the order is easier said than done. While environmentalists welcomed the move, the government may find it difficult to meet the 20-hour deadline. Various transport experts have recommended weighbridges and PUC centres at entry points but nothing has happened. What is also of concern is the absence of space for vehicles to turn around. "Even basic facilities for checking papers are missing at checkpoints. And where is the space for vehicles that are stopped from entering the city to turn around? Unless a proper mechanism is evolved, we will only see more traffic jams at the borders which may prove to be counter-productive," said sources. But those who have welcomed the ban say it will become impossible to battle the growing air pollution problem in Delhi unless some strict measures are taken.

Sources said the bench has also asked various agencies to submit a report on the action taken by them. "The municipal corporations have been asked to prepare a report on the status of open burning of waste in the city. The transport department has been asked to compile a list of all diesel vehicles registered in Delhi that are 10 years old or more. Meanwhile, because construction dust from NCR areas is also creating a problem for Delhi, the court has directed local governments to ensure that all on-going constructions in the NCR area follow the ministry of environment and forests guidelines of 2010 and NGT's own order of December 2014 where it had laid down measures to be taken by construction companies to curtail pollution. If they are found to be violating these rules, work can be stopped," said sources.

The court has also instructed the agencies concerned to ensure smooth flow of traffic on metalled roads in Lajpat Nagar, Karol Bagh and Chandni Chowk. "These have been taken up as pilot projects. To ensure that traffic is not held up, the court told the agencies to not allow hawkers or stationary vehicles, including rickshaws, on the roads," said sources.