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You need to completely quit smoking
. No occasional puffs. Drink Green tea and eat pineapples as they have antioxidants
necessary for reducing the smoke induced damage to your lungs. Do deep breathing exercises and Pranayam which helps build lung compliance. I don't think there is a specific time that the lungs are freed of smoke and associated particles. It depends on your usage and frequency of smoking as well. Which Surgery are you undergoing.