Kolkata’s air is laden with particulate matter 2.5 (PM2.5) that’s emitted from diesel vehicles.

PM2.5 is the fine particulate matter with a diameter of 2.5 micrometers that, when inhaled, travels straight to the bloodstream. A human hair, by way of comparison, is 100 micrometers thick.

Diesel is the source of three highly toxic pollutants: oxides of nitrogen ( NOx), sulphur dioxide (SO2) and suspended particulate matter (SPM). Nearly all of NOx and SO2 present in Kolkata’s air, and all of the SPM, are emitted by diesel vehicles.

The particulate matter in diesel exhaust is coated with highly carcinogenic polycyclic aromatic hydrocarbons (PAHs).

Wednesday (6 November) saw Kolkata being enveloped in a thick gray haze and its citizens struggling to breathe.

The city’s Air Quality Index (AQI) --- a measure of toxic pollutants in the air we breathe --- shot past the 400 mark, making Kolkata the country’s most polluted city.

While the burning of paddy stubble by farmers is blamed for pollution in Delhi, it is old and smoke-belching diesel vehicles that are the culprits in Kolkata. And that makes Kolkata’s air deadlier than Delhi’s.

The World Health Organisation (WHO) says that SPM is the most serious of air pollutants, killing about 4.6 lakh people around the world each year. Some 1.35 lakh of these are victims of chronic asthma. The rest die of cardiovascular or heart diseases, something that Kolkatans are very familiar with.

Kolkata, says environmentalist Subhas Datta who has filed and won many cases on environmental issues, is the “diesel capital” of the country. “Ninety percent of commercial vehicles plying in Kolkata run on diesel. This percentage is much lower in all other metropolitan cities,” said Datta.

What’s more, due to lack of political will and the politics of appeasement, lax pollution control measures, endemic corruption at vehicular emission testing centres and adulteration of diesel, the quality of diesel used by vehicles in Kolkata is extremely poor.

“Most of the commercial vehicles running in the city and a large percentage of diesel-fuelled private vehicles violate emission standards,” said Datta.

The powerful transport lobby has prevented the implementation of repeated court directives on curbing vehicular pollution in the city.

In August 2016, the National Green Tribunal (NGT) asked the Bengal government to phase out all commercial vehicles that are more than 15 years old. Due to pressure from this lobby --- the influential taxi, bus and truckers’ bodies that provide money and musclemen to politicians and political parties --- this directive was never implemented.

Last year, the NGT ordered the state government to ban all commercial vehicles more than ten years old from plying in the Kolkata Metropolitan area. The government was also asked to extend the ban to private vehicles that are more than 15 years old. This directive, too, remained only on paper.

Datta and other environmentalists, as well as auto-emission experts, say it is not just about the age of vehicles in Kolkata, though that too is a major factor behind vehicular pollution.

“Most vehicles, including private ones, plying in Kolkata are not maintained properly and thus do not comply with auto-emission norms,” said Datta. Thanks to corruption at the auto-emission checking centres, all polluting vehicles easily get ‘Pollution Under Control’ (PUC) certificates.

Independent studies estimate that 30 per cent of the diesel sold in Kolkata is adulterated. Adulterated diesel is more polluting and the exhaust of vehicles running on adulterated fuel contains three times more carcinogens than ones running on unadulterated fuel.

According to Tapan Bandopadhyay, the secretary of the Joint Council of Bus Syndicates (an apex body of private bus owners), half the buses running on Kolkata’s roads are more than 10 years old.

If the NGT order of 2018 is implemented, most bus owners would go out of business, he says.

Sanjib Roy of the Bengal Taxi Association says that 60 per cent of the yellow taxis (all smoke-belching ambassadors) in Kolkata are more than 10 years old and if they are banned from plying in the city, their owners will be reduced to penury and hundreds of taxi drivers would become jobless.

The state government has, so far, accommodated the concerns of the bus, taxi and truck operators. And in doing so, says Subhas Datta, they have ignored the health and well-being of Kolkata’s citizenry.

That is why the city --- according to a study conducted by Kolkata’s Chittaranjan National Cancer Institute, Bengal's department of environment and the Central Pollution Control Board, Kolkata --- is the ‘lung cancer capital’ of the world!

Seventy percent of Kolkatans suffer from respiratory diseases, the study revealed.

The problem of air pollution caused by vehicular emission in Kolkata is compounded by the city’s narrow and congested roads, lack of adequate road space and slow-moving traffic.

Vehicles idling at the city’s frequent traffic intersections or moving slowly (the average traffic speed in Kolkata is 25 kilometers an hour) result in greater emission and, thus, pollution.

Kolkata also has the largest number of roadside food vendors in the country. More than 90 per cent of them use coal and wood to prepare the food. This, say environmentalists, is a major contributor to air pollution.

The NGT in 2016 asked the state government to ban the use of coal and firewood by these vendors but the order has been flouted because the vendors form a powerful vote bank.

The NGT has now asked the state government to prepare and submit a time-bound action plan within four weeks on the action to be taken to comply with their 2016 order.

At a hearing on Monday (4 November) where state chief secretary, Rajeeva Sinha, was present, the NGT imposed a fine of Rs 10 crore on the Bengal government for not implementing the 2016 order.

For Kolkatans gasping for breath, the only hope now is the NGT. Datta says that he will plead with the NGT not to give Bengal any more leeway and ensure that the tribunal’s orders are implemented in letter and spirit.

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