The Massachusetts Department of Public Health claims "non-smokers, especially children, who are exposed to secondhand smoke can inhale up to seven times the amount of nicotine inhaled by a smoker." Which is true, if the smoker is smoking the world's tiniest cigarette.
Michael Siegel calculates that a nonsmoker "who spends 12 hours a day in the most heavily polluted smoke-filled room imaginable" (an enclosed smoking lounge) would inhale the nicotine equivalent of about half a cigarette a day. He estimates that a pack-a-day smoker gets about 130 times as much nicotine as a nonsmoker who works an eight-hour shift in a smoky bar.
The numbers are not really necessary to figure out that deliberately inhaling the smoke from a cigarette is a more efficient way of absorbing nicotine than sitting in a room where a little bit of nicotine is mixed with a whole lot of air (not to mention the fact that smokers get at least as much secondhand smoke as nonsmokers do). By my calculation, the Massachusetts Department of Public Health is seven times as full of crap as the average tobacco company executive.