Nicotine has a half-life averaging two hours. Smokers usually begin their day with low nicotine levels that rise sharply in the morning, plateau in the afternoon when smoking slows, and fall during sleep. Each smoker has a characteristic, 24-hour blood nicotine curve and maintains blood nicotine levels within a specific range for each hour of the day. Two thirds of new recruits to smoking are children, between ages 9 to 16. Children, after they make the transition to daily smoking, often move quickly to early addiction.
Adolescents identify physicians as a highly credible source of information about smoking.
Individual smoking varies with age, geographic region, ethnic group, and the smoking behaviour of their family, friends and workmates. The vast majority of those who stop smoking do so on their own, without formal help. But few smokers manage to quit on even their second or third attempt. Thus, the potential strength of medical care is to sustain and support smokers efforts to quit. In other words, for every 43 patients who receive brief intervention, one will quit smoking.