New Delhi, Feb. 13: Seven towns in Bengal are among only nine in India with "double-trouble" air pollution caused by critically high levels of tiny soot-like particles and nitrogen dioxide linked to respiratory and cardiovascular diseases, researchers said today.
The levels of particulate matter smaller than 10 micrometres (PM10) and nitrogen dioxide gas in Asansol, Barrackpore, Calcutta, Durgapur, Howrah, Raniganj, and Sankrail are 1.5 times or higher than standard limits, the Centre for Science and Environment (CSE) said.
Only two other towns in the country ' Badlapur and Ulhasnagar, both in Maharashtra ' have similar critical levels of both pollutants, the CSE said, presenting its analysis of air pollution data collected by the Central Pollution Control Board (CPCB), a government agency, from 180 towns across the country.
The analysis, presented today at a conference on the health impacts of air pollution, has revealed that only two towns ' Malappuram and Pathanamthitta, both in Kerala ' meet the criteria of low pollution, with levels of all air pollutants there half or below the standard limits.
"The CPCB data does not specify site-specific sources (of air pollution), but we believe vehicular traffic, industry-associated emissions and the burning of solid fuel are all contributing to the double-trouble in these nine towns," said Anumita Roychowdhury, the executive director for research at the CSE.
An international research effort to analyse disease burden has estimated that air pollution contributed 627,000 deaths and 17.7 million years of healthy life lost in India during 2010.
Scientists tracking the health impacts of air pollution told the conference that indoor, or household, air pollution mainly caused by the burning of solid fuels such as firewood, biomass, or cowdung has emerged the second biggest risk factor for deaths in India, after high blood pressure.
"The evidence is unequivocal ' we can't just wish this away, we need interventions to tackle both outdoor air pollution and household air pollution," said Kalpana Balakrishnan, the director of the Indian Council of Medical Research Centre for Advanced Research in Environmental Health, Chennai.
"The range of the health effects (from air pollution) are broader and the magnitudes bigger than had been previously estimated," said Balakrishnan, who was part of the international team that has tried to investigate the myriad causes of disease burden.
While air pollution has been traditionally linked to respiratory conditions such as asthma and chronic obstructive pulmonary disease, Balakrishnan said, a range of studies have over the past decade associated air pollution with cardiovascular diseases and cancer.
The link with cardiovascular diseases has hoisted household air pollution to the second biggest risk factor for death in India, causing even more deaths than tobacco smoking or second-hand smoke, according to the international study led by the Health Effects Institute (HEI) in the US.
"Smoking comes with a high risk of cardiovascular disease but we have a relatively smaller population exposed (to smoking), but while household air pollution has a lower risk, the population exposed is huge ' nearly 700 million," Balakrishnan said.
The HEI study to estimate the global disease burden observed a substantial rise in cardiovascular diseases ' coronary heart disease, stroke and chronic obstructive pulmonary disease ' around the world, including in India and other developing countries.
Environmental health scientists expect that the burden of these diseases in the nine towns with critically high levels of both PM10 and nitrogen dioxide would be higher than other places with lower levels of pollutants.
"We don't yet have a good way of estimating the health effects of a mixture of pollutants, but both these act via chronic inflammation that increases the risks of both respiratory and cardiovascular illness," Balakrishnan said.
Scientists say carcinogenic chemicals can enter the body through PM10. "Carcinogens can travel on the particles," said Aaron Cohen, the principal epidemiologist at the HEI. "When you breathe the particle, you don't get the particle alone, you also get the carcinogen."