Despite a steady decline in the prevalence of smoking among men, half of adult males in Japan still smoke. Smoking restrictions in the workplace have been introduced on voluntary basis. First promulgated in 1996, national guidelines for restricting smoking in the workplace recommended the establishment of designated smoking areas. The decline in smoking among men, combined with the growing numbers of women (among whom smoking prevalence remains low) at the workplace, has expanded the at-risk population of nonsmokers facing involuntary exposure to second-hand smoke at the workplace.