and exercise duration compared with performance in the same person when he or she has not been smoking (Hirsch et al., 1985). Reductions of 5–10% in maximal aerobic power and endurance have been estimated in young male smokers compared with nonsmokers (Astrand and Rodahl, 1970).

Smokers have lower physical-performance capacity than nonsmokers as assessed by scores on the Army physical-training test (running, pushups, and situps) (Zadoo et al. 1993), the Navy physical-readiness test (Conway and Cronan, 1992), and other physical tests (Cooper et al., 1968; Gordon et al., 1987; Hartling, 1975; Jensen, 1986; Marti et al., 1988). In some studies, smokers respond less well to physical training, with a smaller increase in endurance over the course of the training program compared with nonsmokers (Blair et al., 1984; Cooper et al., 1968; Frayser, 1974; Hoad and Clay, 1992).

Night Vision and Hearing

Most studies indicate that smokers have slower dark adaptation and lower visual acuity in dim lighting after smoking than nonsmokers (McFarland, 1970); one study, however, showed that night vision improves in smokers immediately after smoking although those smokers were not compared with nonsmokers (Gramberg-Danielsen et al., 1974, cited in Dyer, 1986). Poorer night vision in pilots who were smokers than in nonsmokers has been reported (Durazzini et al., 1975). One study found that visual sensitivity improved in smokers after several hours of nonsmoking (Luria and McKay, 1979).

Smoking has been strongly associated with accelerated hearing loss during aging. In a cross-sectional US population study (Cruickshanks et al., 1998), smoking was associated with a 70% increase in hearing loss compared with that in nonsmokers; the magnitude of the hearing loss appears to be dose-related in middle-aged men (Uchida et al., 2005). A meta-analysis indicated that smoking increases the risk ratio for hearing loss to 1.33 in cross-sectional studies, 1.7 in cohort studies, and 2.39 in case-control reports (Nomura et al., 2005). Smoking also appears to interact with noise in further inducing hearing loss (Pouryaghoub et al., 2007). Smoking causes hearing loss predominantly in middle-aged and older people, but the risk of hearing loss is also strongly increased by smoking in people under 35 years old (Sharabi et al., 2002). Thus, smoking, particularly in combination with noise, which is common in the military, can result in hearing impairment in active-duty personnel.

In summary, there is some evidence that smokers perform more poorly than nonsmokers in low-light conditions. It is not known whether that impairment is related to smoking or to nicotine withdrawal. In either

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