Once you start smoking it is hard to stop because the nicotine contained in tobacco products is so quickly addictive and is even considered to be as addictive as heroin or cocaine.
Why?
When a cigarette is smoked, nicotine-rich blood passes from the lungs to the brain within 7 – 10 seconds and immediately stimulates the release of many neurotransmitters including dopamine (pleasurable feeling).
It is important to note that nicotine is very powerful and poisonous for the nervous system. There is enough (50 mg) in four cigarettes to kill a person within just minutes if it were injected directly into the bloodstream.
The problem is the effects from smoking are short-lived, lasting only a few minutes to a couple of hours. This leads people to smoke throughout the day to dose themselves with this deadly chemical because they want to continue to have whatever positive effects they think they are receiving. Add to this the fact that you can become tolerant to nicotine’s effects — you need to use more and more of it to reach the same degree of stimulation or relaxation — and you can see how people would quickly move from smoking one cigarette to a pack a day habit.
A typical smoker will take 10 draws on a cigarette over a period of 5 minutes. Therefore, a person who smokes about 1-½ packs (30 cigarettes) daily, is getting 300 “hits” of nicotine to the brain each day.