Experts at the Indraprastha Apollo Hospital on Wednesday said that lung cancer cases among non-smokers have increased five-fold in the past decade. For the past few years winters in the North of India have been particularly tough as the majority of the cities get engulfed in a thick blanket of smog which consists of concentrated particulate matter the hospital said. The worsening air condition is a major contributor to lung cancer and other respiratory diseases especially in the months of November-January we breathe in air as toxic as 70 cigarettes a day Dr Sudha Kansal Senior Consultant Pulmonology & Respiratory