What happens in Calcutta
Calcutta’s air is most affected by the toxic emission from vehicles
Buses contribute 40% of the overall vehicle pollution in Calcutta, according to an Asian Development Bank study
Autos account for 32% of the overall vehicle pollution in the city
All vehicles combined contribute 50 to 70 per cent of the city’s air pollution, according to various
The pollution declined marginally after the 2008 judicial crackdown but the level has again increased
in the past three years
Although two-stroke autos are banned, they continue to ply on the fringe areas of the city
Adulterated fuel in some two-stroke autos injects the atmosphere with more respirable particulate
matter which settles in the lungs
New Delhi, Oct. 17: Air pollution has been cast into the world’s list of proven cancer-causing substances — as bad as tobacco smoke.
The World Health Organisation’s cancer agency today classified outdoor air pollution as carcinogenic to humans in a move that researchers here are hoping will stir India into improving its air quality, long implicated in premature deaths.
A panel of experts convened by the WHO’s International Agency for Research on Cancer (IARC) to review scientific literature on the topic has concluded that there is sufficient evidence to show that exposure to outdoor air pollution causes lung cancer.
The panel has classified air pollution, including tiny inhalable particles called particulate matter, in the same category of proven carcinogens as tobacco. The main sources of outdoor air pollution are vehicle emissions, thermal power plants, industrial and agricultural emissions and indoor heating and cooking, the IARC said.
Nearly 60 per cent of India’s power comes from power plants that burn coal.
The IARC had in the past evaluated specific chemicals or mixtures such as diesel engine exhaust, solvents and dusts that occur in outdoor air pollution. But this is the first time its expert panel has labelled outdoor air pollution as a Group 1 carcinogen, a tag assigned if a positive cause-and-effect relationship has been observed between exposure to a substance and cancer.
“The risk of developing lung cancer is significantly increased in people exposed to air pollution,” said Dana Loomis, an epidemiologist and deputy head of the monographs section at the IARC. The review also observed an increased risk of bladder cancer.
“We consider this to be the most important environmental carcinogen, more so than passive smoking,” said Kurt Straif, head of the IARC department that evaluates cancer-causing substances.
Straif said that the most polluted metropolises were in China and India.
A Yale University study released earlier this year had claimed that India had the worst air quality among 132 countries assessed. Other independent studies based on mathematical models of the impacts of polluted air on health have indicated that India’s megacities, including Calcutta and Delhi, are among the world’s worst polluted cities, and hence have among the highest levels of premature deaths.
“About 20 per cent to 30 per cent of lung cancers occur in non-smokers,” said Digambar Behera, a senior pulmonologist at the Postgraduate Institute of Medical Education and Research, Chandigarh. “This decision formally labels air pollution as harmful as tobacco smoke,” Behera told The Telegraph.
The IARC has estimated that air pollution caused 223,000 lung cancer deaths worldwide during 2010. Behera, who is the president of the Indian Society for the Study of Lung Cancer, said about 57,000 people are diagnosed with the disease each year in India.
The Centre for Science and Environment, New Delhi, which has analysed air quality data collected by the government from 227 cities and towns across India, estimates that nearly half the country’s urban population is exposed to air with particulate matter levels higher than safe limits.
The CSE analysis also suggests that about one-third of the urban population live in areas where the levels are critical. “An increased risk of lung cancer comes at an enormous economic and social cost,” said Anumita Roy Chowdhury, executive director for research at the CSE, a non-governmental organisation.
A study, published earlier this year in the journal Atmospheric Chemistry and Physics, based on global air quality data from 2005, has estimated that around 14,200 people in Calcutta and 17,600 people in Delhi die prematurely each year from cardiovascular disease, respiratory illness or lung cancer linked to air pollution.
The National Cancer Registry maintained by the Indian Council of Medical Research has data on lung cancer but no evidence correlating lung cancer to air quality. “We haven’t had any systematic studies looking for such correlations,” said Ambakumar Nandkumar, head of the NCR project in Bangalore.
“It is a pity we don’t have such studies,” said Bhola Ram Gurjar, an environmental chemist at the Indian Institute of Technology, Roorkee, who has been trying to study the impact of air quality on the health of the population. “Most epidemiological studies have been based on observations in Europe and North America — we need similar data from India.”
The IARC said its expert panel had reviewed epidemiological studies from Asia, Europe, and North and South America.