Working Time Traffic Light recommendations: development, use, and implementation in the Finnish social and healthcare.

The Working Time Traffic Light (WTTL) recommendations are detailed guidelines aimed at mitigating the health and safety effects of shift work. This paper reviews the development, implementation, and effects of the WTTL recommendations in social and healthcare. Based on the payroll-based Working Hours in the Finnish Public Sector (WHFPS) cohort of over 300,000 employees, we analysed many dose-response associations of different working hour characteristics with health and safety and developed cut-off levels and evaluation tools for the traffic light-based WTTL recommendations. The recommendations were implemented in the social and healthcare sector by embedding the recommendations into shift scheduling software in co-operation with commercial software producers, and by giving feedback on the working hour characteristics to the healthcare organizations and policymakers. Based on a 5-year follow-up, the WTTL recommendations were well-known, and used regularly by 20% of the shift planners. Compared to the non-users, the regular use of the evaluation tool was associated with improved working hour patterns, a lower number of occupational accidents, and a decrease in psychological distress. Based on the established use of the recommendations and their effects on health and safety, the development and implementation of the WTTL recommendations can be regarded as successful.