Kolkata has upstaged Delhi as the air pollution capital of India, accounting for more deaths due to lung cancer and heart attack than the capital city.

More than 18 persons per one lakh people in Kolkata fall victim to lung cancer every year, compared to the next highest 13 per one lakh in Delhi, according to environmental scientist and advisor of Chittaranjan National Cancer Institute, Twisha Lahiri.

Not only lung cancer, cases of heart attack were also rising fast in the Eastern metropolis, Lahiri said, quoting a six-year survey conducted by the cancer institute. She said incidents of heart attack were occurring more frequently in the city.

CNCI scientists maintain that more than seven in 10 people in Kolkata, including children as well as elderly people, suffer from various kinds of respiratory disorders.

Lahiri said roadside hawkers, shopowners, traffic policemen, auto-rickshaw drivers, rickshaw-pullers and others who spend long hours on the road were the most vulnerable.

Children mainly suffer from breathing difficulties like asthma while elderly people are victims of lung cancer, the scientists said.

Lahiri said air pollution was increasing in pace with the rapid increase in vehicular population and also because of the ageing fleet of buses, which need to be discarded.

Nearly 80 per cent of the buses and trucks and nearly half of the taxis and auto-rickshaws will have to be pulled off the roads to clean the city's air, environmentalists felt.

"What we need is immediate introduction of CNG or LPG-driven buses, strict monitoring of auto-rickshaws which run on adulterated fuel and withdrawal of old buses belching toxic fumes," she said.

Environmentalist Subhas Dutta had filed a PIL in the Calcutta High Court, alleging that the Bengal government was idle about controlling air pollution level.

"After a series of petitions and court rulings, very little was done to curb the killer pollution. That is inadequate and the fight will continue," Dutta said.

Street hawker Ramesh Ghosh says that his eyes often burn and he feels breathless after long exposure to fumes.

"Doctors have advised me to stay away from roadside, but I cannot afford to do it as I will die of hunger," Ghosh said.