New Delhi, July 18: Air pollution, exposure to secondhand smoke, occupational hazards, and indoor pollutants like cooking fumes are responsible for the rising cases of lung cancer, even among people who do not smoke, said experts on Thursday.A recent research, published in the Lancet’s eClinical Medicine Journal, showed that the ratio of lung cancer research output in India to global research output is 0.51.The study revealed that lung cancer develops 10 years earlier in India than in Western countries, where the age of diagnosis ranges from 54 to 70. It could also be the result of India’s younger population where the median age is 28.2 years, compared to the US’ 38 years and China’s 39 years.Speaking to IANS, Dr. Shrinidhi Nathany from the Department of Molecular Hematology and Oncology at Fortis Memorial Research Institute said increased lung cancer incidences among non-smokers in Southeast Asia are also linked to high PM 2.5 levels.