The state government is making “no serious effort” in phasing out old polluting commercial vehicles, the National Green Tribunal said on Thursday.

The bench comprising Justice S.P. Wangdi and expert member Nagin Nanda said in an order on Thursday: “The next question that we find the state lagging in is with regard to phasing out of old commercial vehicles, as evidently no serious effort is being made in this regard.”

Goods vehicles were found to be responsible for the bulk of automobile pollution in Calcutta and Howrah, a study by the National Environmental Engineering Research Institute (NEERI) has revealed. The report said that goods carriers were responsible for 49 per cent of the PM10 in the ambient air generated by vehicular emission. For PM2.5, the contribution of goods vehicles was estimated at 49.5 per cent.

Phasing out of commercial vehicles more than 15 years old is one of the ways to maintain a healthy air quality, said air quality management specialists. “A truck that was manufactured in 2000 under the BS-IV emission norms will emit 36 times more particulate matter than a truck manufactured under the BS-VI norms. If you can phase out commercial vehicles that are more than 15 years old, you get a lot of emission benefits,” said Anumita Roy Chowdhury, the executive director of the Centre for Science and Environment.

BS-IV and BS-VI are emission standards of a vehicle’s engine. The Centre has mandated that vehicle makers must manufacture and sell only BS-VI (BS6) vehicles from April 1, 2020.

Calcutta High Court had in 2008 ordered a ban on the movement of all commercial vehicles 15 years or older in the Calcutta Metropolitan Area (CMA) to tackle pollution caused by vehicular emission.

On Thursday, the tribunal also directed the transport department to ensure that a committee formed to deal with the issue submits its report “in not more than three months days from hence”.

The observations were made while passing an order on a petition by environment activist Subhas Datta about air pollution in Calcutta and Howrah. Datta said that during the course of the hearing of the case, the Union ministry of road and transport told the tribunal that there were 2.19 lakh commercial vehicles in Calcutta of age 15 years or older.

The tribunal also told the state “to ensure that the public transport vehicles below BS-IV are phased out rapidly to arrive at a stage when only BS-VI would ply in the two cities, to be extended gradually to the rest of the state”.

The bench observed that the “…decline in quality of environment demonstrates the failure of the authorities to perform their obligation under the constitutional scheme and mandate of the environmental laws”.

It threatened to apply the “principle of accountability for restoration and compensation… if the regulatory authorities either connives or acts negligently by not taking prompt action to prevent or avoid or control damage to the environment….”

The bench also said it was accepting the state’s action plan on combating air pollution, which was submitted on August 17.

The action plan talks about various measures such as phasing out of old vehicles, afforestation, use of clean fuel in roadside eateries, stopping open burning of waste and using water sprinklers.

“The government is trying its best” claimed government lawyer Abhratosh Majumdar during the video hearing. “We have just received the order and will implement as per the direction” said a senior state pollution control board official.