smoking lots of cigarettes What is a Cigarette Pack Year? Sharp increase in middle-class women

2014;307:L205-218

To be clear, no cigarette is safer even if it contains much less nicotine

Alton Ochnser and Michael DeBakey wrote that In our opinion, the increase in cigarette smoking, with the universal custom of inhaling, is probably a responsible factor, as the inhaled smoke, constantly repeated over a long period of time, undoubtedly is a source of chronic irritation to the bronchial mucosa. Even though 76 per cent of the 147 cases of lung cancer they analyzed in their 1947 article in JAMA were from individuals who had smoked, they did not believe that the history of smoking had special significance

doi: 10.1016/j.jsat.2005.07.001