Vaping, best way out of cigarettes

My father is 67 yrs. old. He has COPD. Over half of his lung capacity has gone. Despite that he continued smoking until I introduced to him a modern, top quality, easy to use, refillable e-cig and 24 mg/ml nicotine liquid with tobacco flavour. He struggled about one month as a dual-user, but eventually he got rid off cigarettes for good. Its amazing how much switching smoke to vapour has improved his health and well-being. Maybe he got couple of years more to live, thanks to ecig.