Smoking As A Drug-Taking Activity

Most smokers absorb sufficient nicotine to obtain pharmacological effects. The modern cigarette is a highly effective device for getting nicotine to the brain.
The smoke is mild enough to be inhaled deeply into the lungs. Due to the large surface area of the lungs, nicotine is absorbed rapidly into the bloodstream and reaches the brain within 7 seconds - more rapidly than after an intravenous injection.
In this way the smoker gets a small intravenous-like shot of nicotine after each inhaled puff: 20 cigarettes a day, each puffed 10 times, comes to more than 70,000 "shots" per year.
On average, smokers take in about 1 milligram (mg) nicotine from each cigarette, although some take 2 milligrams or more while others are satisfied with 0.5 milligrams or less. By altering puff-rate, puff-size and amount of inhalation, smokers unconsciously regulate their nicotine intake to their individually preferred levels, which are kept fairly constant from one day to the next.
The nicotine yields of the cigarettes make little difference. By puffing harder, inhaling more deeply, and smoking down to the tip, smokers can get 2 milligrams of nicotine or more from a low-yield cigarette with an official machine-smoked yield of only 0.6 milligrams. Cigarette smokers literally do have fingertip control over the delivery of nicotine to their brain.