Background Historically, the arduous sectors of work have been those that are physically heavy such as work in the steel industry. In this context, this arduousness is related to significant thermal constraints caused by the production processes. In Tunisia, this sector employs more than 2498 workers. This study aims to identify the heat strain at work in the steel industry by measuring the metabolism of work.

Methods A cross-sectional and exhaustive study was conducted in a steel company located in the governorate of Monastir (Tunisia). The study was conducted in the hot season during the months of August and September 2015. The evaluation of the thermal constrain was made through the evaluation of the metabolic rate in accordance with the recommendations of the ‘analysis’ level of the international standard ISO 8996 ‘Ergonomics of the thermal environment -- Determination of metabolic rate’. This analysis was based on the recording of heart rate during work.

Results A total of 80 male workers aged 37.9 +/- 9.25 years and having an average job tenure of 12.5 ± 11.4 years were included. The mean absolute cardiac cost was 18.67 ± 6 beats per minutes. The average relative heart rate was 17.1% ± 5.8%. The equivalent metabolic rate was estimated at 292.7 ± 59.8 Watts. The interpretation of the workload based on the equivalent metabolic rate, the percentage of use of the maximum work capacity and the limit time for this metabolic load was rated as acceptable for the majority of workers (84.8%).

Discussion and Conclusion In Tunisia, the steel sector is an active sector of activity. The present study objectively quantified the physical workload in the steel sector in hot season. For most workers, the workload was light to moderate. Nevertheless, a preventive approach combining technical, organizational and medical actions should be implemented.