Alcohol and driving-How bad is the combination? A meta-analysis.

OBJECTIVE: The objective of this study was to summarize existing knowledge on the association between driving under the influence of alcohol and road safety outcomes and to assess factors that may explain why these estimates vary. METHODS: Based on studies of the association between blood alcohol concentration (BAC) levels and crashes, we used multilevel metaregression to calculate summary effects of BAC level and analyze potential moderators of the association. RESULTS: Based on 60 studies and 393 effect estimates, we found that BAC level, outcome severity, use of hospital data, and geographical region contributed to heterogeneity in results. CONCLUSION: The effect of BAC on crash and injury risk and culpability is stronger at higher BAC levels and for more serious outcomes. The relationship between BAC level and outcome is approximately exponential. The relationship is stronger in studies from Nordic countries than in studies from other countries, possibly because of the relatively low level of drunk driving in these countries. Studies based on hospital data and studies using non-crash-involved control groups find smaller effects on average.

How can regulatory authorities improve safety in organizations by influencing safety culture? A conceptual model of the relationships and a discussion of implications.

Regulators have increasingly started to focus on safety culture. The causal link between regulatory initiatives to improve safety culture and a potential decline in accidents may, however, appear like a "black box", involving social processes that seem hard to foresee and influence. We need a better conceptual understanding of this. The aims of our study are to: 1) Map studies of regulatory efforts to influence safety culture in companies, 2) Use the identified studies to develop a conceptual model of the analytical relationships between regulatory initiatives to improve safety culture and accidents in these studies, including the factors influencing these analytical relationships and 3) discuss practical implications. The review is reported according to PRISMA-guidelines, and focuses on professional transport (aviation, sea, rail, road) and the Norwegian petroleum sector. Our review indicates at least six analytical relationships, mediating between regulatory attempts to influence organizational safety culture and accidents. These are between: 1) Rules and regulators, 2) Regulators and companies, 3) Managers and employees in the companies, 4) Organizational members' shared ways of thinking and acting, which are the two key elements of safety culture, 5) Safety culture and safety behaviour, and between 6) Safety behaviour and accidents. Regulatory attempts to influence safety culture may fail or succeed at each level, through factors involved in the different relationships.