A majority of the vehicles plying in Kathmandu fail to comply with government standards for exhaust emission, a senior official said Monday.

Department of Environment Senior Divisional Chemist Shankar Prasad Paudel’s admission comes on a day the country celebrates the World Environment Day.

“We found a high number of vehicles violate emission standards and contribute to the air pollution that

chokes residents in the valley,” said Paudel.

Random checks for vehicluar emissions, during the last few months in different parts of Kathmandu Valley, show nearly half of the vehicles fail government standards.Vehicle emission tests started last November. Results show 635 vehicles emitted smoke and other particles far higher than the government standards.

A joint team of the Department of Environment (DoE), Metropolitan Traffic Police Division (MTPD) and Department of Transport Management (DoTM) checked 1,374 vehicles - 708 diesel and 666 petrol.

The number of diesel-run vehicles that do not comply with emission standards is higher than petrol vehicles. Test results show 422 diesel and 231 petrol vehicles crossed permissible emission levels.

Existing emission standards stipulate petrol vehicles, manufactured before and after 1980, should not emit carbon monoxide (CO) more than 4.5 per cent and 3.5 per cent respectively in its total smoke density.CO emissions of old and new diesel vehicles should not cross more than 75 per cent and 65 per cent respectively under Hartridge Smoke Unit (HSU). The DoE plans to introduce measures to take strict action on such vehicles that are major agents of air pollution, Paudel said.

“Besides amending the existing standards to make it strict, we are thinking of switching from Euro 3 to Euro 4 standards for new vehicles in the future,” he said.The DoE should be given the responsibility for overseeing vehicular emission standards as it involves pollution, the official said.Currently, the DoTM conducts vehicle emission tests and penalises violators. “As a concerned body, responsible for environment conservation and pollution control, we have urged transferring the responsibility of vehicle emission tests and penalising to the department,” said Paudel.