When Ashim Chakrabarty, a 38-year-old minibus driver with no history of smoking or diabetes, had a heart attack sometime ago, doctors ran a battery of tests but did not find evidence of any of the conventional causes of cardiac disease. Bypass surgery saved Ashim’s life.

Nandini Sen, a 31-year-old housewife without any symptoms of diabetes and hypertension or a family history of cardiac disease, was diagnosed with multi-vessel coronary artery disease and underwent coronary angioplasty. But as in the previous case, the trigger for the disease was, in medical terms, “unconventional”.

Profiles of young Calcuttans who are falling prey to cardiac disease despite no family history of such ailments or other risk factors have convinced doctors that the culprit is not in their bodies but the air they breathe.

“It has become common for young people without any conventional trigger or family history to be diagnosed with cardiac problems, and we believe that air pollution in the city is to blame for it,” said Kunal Sarkar of the Rabindra Nath Tagore International Institute of Cardiac Sciences.

The chief contributor to air pollution in the city is the fleet of autorickshaws that run on adulterated fuel, or katatel. Studies carried out on behalf of The Telegraph established that katatel was a toxic cocktail of kerosene, naptha and petrol.

Doctors believe this is one of the reasons why Calcutta not only has the maximum number of lung cancer sufferers among all metros but also a growing population with cardiac and respiratory ailments.

“Air pollution has been affecting mainly the very old and very young people, and often pulmonary problems like chronic obstructive pulmonary disorder are found to be associated with cardiac problems,” said chest medicine specialist A.G. Ghosal. An Asian Development Bank study in 2005 revealed that autorickshaws contribute over 98,000 tonnes of pollutants every year.

“Fine air particles, once inhaled, find their way into the blood stream and trigger changes that clog up arteries faster than usual. This explains why premature coronary artery diseases have become so common now,” Sarkar said.