Occupational health surveillance of compressed air workers: a scoping review.

BACKGROUND: Compressed air is increasingly used in the underground construction of caissons and tunnels. New risks have been identified, suggesting the need to develop counter-measures. AIMS: This scoping review aimed to provide insight into the health risks, prevention and surveillance measures, and adverse health effects related to compressed air work during tunnel construction. METHODS: Health risks were assessed based on the Joanna Briggs Institute Reviewers' Manual, the recommendations of Pollock and the PRISMA Scoping Reviews Checklist. The scoping review mapped and analysed studies of compressed air work over the past 50 years. Only 45 studies were deemed eligible for inclusion in this review. RESULTS: In the early days of mechanized tunnel construction, the incidence of decompression sickness was high, affecting up to 2032 individuals, with an incidence rate of the bends as high as 0.5%. Improvements in decompression tables and the use of mixed gases have reduced these rates to below 0.1%. New construction techniques have introduced new health risks, including silicosis. Because of traffic demands, especially in urban areas, newer tunnels have been built for operation at greater depths (up to 106 metres sea water). CONCLUSIONS: Relatively few studies in the past 50 years have analysed the effects of compressed air use for tunnel construction. Adverse health effects have decreased substantially over time, but several new health risks have been described. The registration of key information on health and safety risks and adverse health effects, in a highly accessible international repository is recommended.