A major part of London has recently been declared Low Emission Zone, where heavy-duty diesel lorries violating exhaust norms will be fined up to £1,000 a day.

The declaration stands in contrast to the near-absence of curb-emission attempts in Calcutta, one of the most polluted cities in the world.

Metro scans the state of emission and identifies the culprits...

State of emission: A study undertaken by Asian Development Bank a few years ago had blamed diesel vehicles for 90 per cent of Calcutta’s respirable particulate matter (RPM), a major source of air pollution. The annual average RPM content in the city’s air is 100 microgram per cubic metre, more than 1.5 times the permissible limit of 60.

The fine particulates and nitrogen oxide — emitted mostly by diesel-driven vehicles — have been consistently high in the city.

“Calcutta is a unique case even by the Indian standard. In Delhi, too, the RPM and nitrogen oxide content is higher than the national average, but it is on the decline now. In Calcutta, the situation is just the opposite,” said Anumita Roy Choudhury, an air pollution researcher with the Delhi-based Centre for Science and Environment.

Main culprits: The entire state government machinery in general and the transport department in particular.

The state transport department, tasked with curbing foul fumes, hardly enforces the rule. “And even when half-hearted attempts are made to implement pollution norms, the offenders manage to devise ways to escape the law,” said an environment expert.

“There are only a few commercial vehicles armed with a valid auto emission testing certificate. But inspectors seldom haul them up,” the expert added.

The transport department, headed by minister Subhas Chakraborty, has often been accused of sabotaging attempts to introduce green fuel with active support of transport unions.

During his recent visit to the city, British environmentalist Paul Brown had said: “I am told that the transport minister and transport union leader are the same person here. It is a unique case in the world.”