Yoshihisa FUJINO, et al.: Development a work functioning impairment scale ence of workplace violence and other psychosocial work characteristics. Conclusion: Neighborhood-level workplace violence was associated with poor mental health in female workers. Preventative strategies targeting workplace violence should pay attention to neighborhood factors and gender-specific effects that might influence societal tolerance of abusive work practices and workers' vulnerability to mental health impacts of workplace violence. Workplace violence is a growing mental health concern 1, 2) . According to the International Labor Organization (ILO), World Health Organization (WHO), International Council of Nurses (ICN), and Public Services International (PSI), workplace violence is defined as "incidents where staff are abused, threatened or assaulted in circumstances related to their work, including commuting to and from work, involving an explicit or implicit challenge to their safety, well-being or health". Besides physical violence, violent incidents in workplace can also be psychological, such as verbal abuse, harassment, bullying/ mobbing, and threat 3) . In epidemiologic studies, workplace violence is often classified into the following four types: physical violence, verbal violence, psychological violence, and sexual harassment 4−6) . In a survey conducted in the United States, 0.4% of workers reported having experienced multiple forms of nonfatal workplace violence over the past year 7) . In a Dutch survey, 24% employees were found to have experienced workplace violence in the past year 8) . According to the Fifth Workplace violence is known to pose mental health risks. However, whether or not workplace violence in a surrounding area might further increase the risk of mental distress in workers has rarely been examined.
Methods:The study subjects were 9,393 male and 7,716 female employees who participated in a nationwide survey in 2010. Their personal experiences of workplace violence over the past 1 year were ascertained by a standardized questionnaire. Also assessed were their psychosocial work characteristics and mental distress problems. Neighborhood-level workplace violence was computed based on aggregated data at the county level and was categorized into low-, medium-, and high-level categories. Multilevel logistic regression models were constructed to examine the associations between neighborhood-level workplace violence and individual-level mental distress problems, with adjustment of individual-level experience of workplace violence. Findings: The neighborhood-level prevalence of workplace violence ranged from 4.7 to 14.7% in men and from 6.4 to 14.8% in women across 22 counties. As compared with those who live in counties of the lowest tertile of workplace violence, female workers who lived in counties of the highest tertile of workplace violence had a 1.72-fold increased risk for mental distress problems after controlling for individual experi-