[Differences in nonsmokers' exposure to secondhand smoke at the workplace across job categories in Japan: A cross-sectional study].

Objectives　Differences in exposure to secondhand smoke at the workplace, based on job category, have been assessed in some countries. While differences due to socioeconomic status have been assessed in Japan, few studies have been conducted to examine differences across job categories. We aimed to clarify the differences in nonsmokers' exposure to secondhand smoke at the workplace across job categories in Japan.Methods　This cross-sectional study used data from an online survey conducted in 2017. A total of 1,739 participants, aged 20-69 years, were included. The dependent variable was exposure to secondhand smoke at the workplace, whereas the independent variable was job category, which was classified into the following 7 categories: 1) Management, Professional, and Technical; 2) Clerical; 3) Sales and Service; 4) Security; 5) Agriculture, Forestry, and Fishery; 6) Production Process, Transport, Cleaning, Packaging, etc.; and 7) Transportation, Machine Operation, Construction, and Mining. Analysis included estimates of the prevalence ratios (PRs) for the differences in exposure to secondhand smoke based on job category. In the analyses, sex, age, educational status, income, smoking environment at business, and awareness of secondhand smoke were considered covariates.Results　The mean age of the participants was 43.3 years (SD=11.9); men constituted 60.5% of the study participants. A total of 529 individuals (30.4%) were exposed to secondhand smoke at the workplace in the past month. Of these, 171 (27.9%), 155 (27.1%), 116 (33.7%), 10 (45.5%), 7 (31.8%), 39 (34.5%), and 31 (58.5%) were found from the 1 to the 7 category, respectively. In the multivariate analysis, PRs (95% confidence interval) of exposure to secondhand smoke at the workplace among non-smokers were 1.27 (1.04-1.56), 1.61 (1.02-2.56), and 1.75 (1.33-2.31) for the Sales and Service category; Security category; and Transportation, Machine Operation, Construction, and Mining category, respectively, compared to the Clerical category.Conclusion　Certain job categories may not be able to benefit from secondhand smoke prevention measures, although the measures have been promoted by the revised Health Promotion Act. It is, thus, necessary to monitor the situation of exposure to secondhand smoke at the workplace across diverse settings.