Hi, Thanks for writing in. Smoking exposes the lungs to high doses of chemicals present in smoke called carcinogens. These chemicals are derivatives of tar and fine particles get stuck to the walls of small airways. 3 to 6 cigarettes in a month is acceptable and not a serious concern for cancer but might also trigger asthma and respiratory problems in few. However some men might find cigarette smoking as a stress reliever and also get addicted to it. This addiction is bad and often people smoke a pack or more every day. By stopping smoking you can certainly avoid medical conditions affecting the lungs including asthma and cancer to some extent. Since you are a social smoker it is easier to quit. Please do not worry.