Relation between smoking prevalence and various social factors in Japan.

Although the smoking prevalence among women is significantly low compared to that among men in Japan, the prevalence in young Japanese women has been steadily increasing recently. The relationship between the prevalence of smoking among the general population and various social factors was investigated with a special emphasis regarding the influence of household size on the smoking prevalence of young Japanese women. Thirty-one thousand and six hundreds twenty-seven subjects of 20 years and older were randomly selected from the general population of Japan. The Ministry of Health and Welfare, Japan planned and conducted the survey. Subjects were divided into male and female, and smoking prevalence was investigated in terms of age, place of residence, occupation and household size factors. Statistical analyses were performed using chi-square test and multiple logistic regression. Multiple logistic regression analyses suggested that for men there was a strong relationship between becoming a smoker and living in a municipality with a smaller population, and that for women who were living in a municipality with a larger population. For women, as the size of a household increased from living alone to a two- or three-generation household, the tendency to becoming a smoker decreased, but this tendency was not observed among men. As to reasons for quitting smoking, more women than men living in two- and three-generation households gave "family's advice" as a major reason (p < 0.01). The steady replacement of the traditional three-generation household by smaller households in Japan may lead to an increase in the number of young women who smoke.