Are Partial Workplace Smoking Bans as Effective as Complete Smoking Bans? A National Population-Based Study of Smoke-Free Policy Among Japanese Employees

Introduction: Although complete workplace smoking bans are generally recommended rather than partial bans, the latter are widespread in many countries, especially Japan. Our objective was to compare complete workplace smoking bans and partial bans for associations with employee smoking and secondhand smoke (SHS)-related discomfort/ill-health. We also evaluated complete bans versus no ban and partial bans versus no ban.

Methods: Eleven thousand ninety eligible employees (weighted number: 34 353 241) aged 20-64 years in 2011 (response rate: 62.5%) were analyzed using a nationally-representative, population-based cross-sectional study. Adjusted prevalence ratios for self-reported current smoking and SHS-related discomfort/ill-health according to workplace smoke-free policies were calculated, using conventional regression and propensity score (PS) weighting (targeting population of average treatment effect among both treated [TET] and untreated [TEU]).

Results: Both conventional regressions and PS weighting analyses showed complete bans were significantly associated with lower prevalence of current smoking and perceived SHS-related discomfort/ill-health among nonsmokers than partial or no ban. In contrast, partial bans were not significantly associated with either outcome compared with no ban. Using several PS trimming levels, we found interesting differences between TET and TEU in a comparison between partial and no ban: that is, significant associations in TET estimations, but none in TEU estimations.

Conclusions: Although complete smoking bans were associated with lower levels of employee smoking and SHS-related discomfort/ill-health compared with no smoking ban, partial bans were not. Findings from PS weighting of TEU suggest that partial workplace bans may not be any more effective for Japanese employees than no ban. Therefore, complete bans may be strongly recommended for future implementation, but careful interpretation of the data is necessary because of the cross-sectional study design.