Of the 8,842 subjects, 4,205 were recruited from Ansung and 4,637 from Ansan, Korea. Their average ages were 55.6±8.74 (standard deviation; SD) and 49.1±7.86 years, respectively. Although 52.7% of the participants (N = 4,659) were female, only 4.93% of these were considered either former (1.34%), light (1.29%), or habitual (2.30%) smokers. In contrast, 80.62% of the male subjects were smokers, with 31.05% being former smokers, 4.78% light smokers, and 44.79% habitual smokers. For those habitual smokers, the average number of cigarettes smoked per day (CPD) was 19.51±8.74 for male and 11.93±7.28 for female smokers. A detailed description of the characteristics of all subjects is presented in Table 1.
