Their most serious challenge before the 1990s came in 1983, when Rose Cipollone, a smoker dying from lung cancer, filed suit against Liggett Group, charging the company failed to warn her about the dangers of its products.

CNN: A brief history of tobacco

Alternatively, it may be part of cognitive dissonance, which happens when a person's beliefs are not in line with their behaviors -- for instance, a smoker who berates other smokers.

CNN: Why zombies, robots, clowns freak us out

Nabi's work on a smoker's vaccine dates to 1996, when Ali Fattom, the company's vice president of research, came up with a workable vaccine for Staphylococcus aureus, a leading cause of infection in hospitals.

FORBES: A nicotine vaccine may help smokers stop for good.

Philip, a non smoker, said Mark's face "lit up" when he thought he could smoke before their flight.

BBC: Smoking