W hile lung cancer's link with smoking has been publicised, its link with air pollution is considerably underplayed. "Data do suggest that urban smokers are more likely to develop lung cancer than rural smokers, even after accounting for smoking behaviour (how heavily a person smokes, what kind of cigarettes are smoked and so on). Yet urban non-smokers do not appear to be at increased risk for lung cancer,' said Dimitrios Trichopoulos and colleagues at the Harvard Centre for Cancer Prevention in Boston, usa , in a September 1996 article in the Scientific American .

"Taken together, such studies, emission inventories and chemical analyses of air samples from urban areas suggest that long-term exposure to high levels of air pollution could increase lung cancer risk by about 50 percent, especially among smokers. Diesel exhaust, which is probably more carcinogenic than non-diesel exhaust, has been proposed as a likely carcinogenic factor,' they conclude. It is well known that Indian cities use a lot of diesel, and only one pollutant, suspended particulate matter, which is linked to diesel exhaust emissions, accounted for 52,000 lives in only 36 cities of India in 1995 (see