average of 21 cigarettes per day. Pilots were given computerized mental-arithmetic, visual-vigilance, and image-recall tasks in conditions of ad libitum smoking and after 12 hours of tobacco abstinence on separate days. Cigarette abstinence was associated with impaired performance in all tasks; there were significant decrements in the mental-arithmetic and image-recall tasks. Given that pilots need to retain and evaluate multiple conditions and make quick decisions, the authors of the study concluded that abrupt cessation of smoking is likely to be detrimental to flight safety (Giannakoulas et al., 2003). A 1994 CDC report found that performance disruption would not be a significant impairment for most flight personnel for 4 hours following the last cigarette and that nicotine replacement medications could alleviate withdrawal symptoms associated with longer periods of deprivation (Fiore et al., 1994).
Military diving is highly demanding with respect to both general physical endurance and respiratory function. Longitudinal and cross-sectional studies have found decreased pulmonary function, as measured by forced expiratory volume in 1 second as well as other pulmonary-function tests, in divers who smoke compared with divers who do not smoke (Dembert et al., 1984; Tetzlaff et al., 2006). Obstructive airways disease secondary to smoking would be expected to be hazardous during diving in general.
Diving-related symptoms of decompression illness are more severe in smokers. Severe decompression illness may include alteration in consciousness and balance, bladder- or bowel-control problems, motor weakness, visual symptoms, or convulsions. There is a dose-response relationship between intensity of smoking and severity of decompression symptoms. Thus, divers who smoke are at increased risk for both aggravation of acute obstructive lung changes and decompression illness (Buch et al., 2003).
Smoking has been associated with an increased risk of motor-vehicle collisions in a number of studies (Hutchens et al., 2008; McGuire, 1972). The incidents may be the result of slower reaction times in smokers who are deprived of nicotine (Heimstra et al., 1967). Smokers are more likely than nonsmokers to have motor-vehicle collisions at night and are less likely to wear seatbelts (Grout et al., 1983). Lighting or manipulating cigarettes, or dealing with falling ashes could divert a smoker’s attention from driving. However, one study found that smoking improves the driving performance of habitual smokers; there may be an optimal nicotine dose for the enhancement of cognitive and psychomotor function (Sherwood, 1995).