Active smoking is a risk factor for occupational injury, whereas its association with passive smoking is unknown. To evaluate the contribution of active and passive smoking to non-fatal occupational injury in manufacturing sectors, 2302 randomly selected workers aged 16-83 years working in 244 small- and medium-scale enterprises in Yashio city, Japan, were surveyed by means of a self-administered questionnaire. Smoking history, exposure to passive smoking, and occupational injury were evaluated by self-report. Exposure levels to passive smoking were assessed separately at work and at home as never, occasional, or regular exposure. Overall, 61.4% of men and 22.3% of women were current smokers. Among never smokers, 62.2% of men and 68.6% of women reported exposure to passive smoking either at work or home. Prevalence of occupational injuries was 36.2% for never, 43.3% for former, and 41.2% for current smokers among men and 19.7% for never, 22.2% for former, and 25.2% for current smokers among women. Among never smoking men, odds ratios (ORs) of occupational injury were 2.11 when regularly exposed to passive smoking at work or at home (p=0.025), 2.27 at work (p=0.015), and 3.08 at home (p=0.106), in comparison to never smoking men who were never exposed to passive smoking either at work or at home (referent group). These associations were attenuated to be non-significant, after controlling for potential confounders. Never smoking men with occasional exposure to passive smoking were not significant ORs (1.11-1.19). In contrast, current and former smoking men had significant increases in adjusted ORs (1.57-2.00). In women exposed to smoking there was a non-significant increase in occupational injury. The present study indicates an expected increase in the risk of, occupational injury for current and former smoking men and suggests that exposure to passive smoking is a possible risk factor for never smoking men.
