title: Health and efficiency in trimix versus air breathing in compressed air workers.
abstract: The Western Scheldt Tunneling Project in the Netherlands provided a unique opportunity to evaluate the effects of trimix usage on the health of compressed air workers and the efficiency of the project. Data analysis addressed 318 exposures to compressed air at 3.9-4.4 bar gauge and 52 exposures to trimix (25% oxygen, 25% helium, and 50% nitrogen) at 4.6-4.8 bar gauge. Results revealed three incidents of decompression sickness all of which involved the use of compressed air. During exposure to compressed air, the effects of nitrogen narcosis were manifested in operational errors and increased fatigue among the workers. When using trimix, less effort was required for breathing, and mandatory decompression times for stays of a specific duration and maximum depth were considerably shorter. We conclude that it might be rational--for both medical and operational reasons--to use breathing gases with lower nitrogen fractions (e.g., trimix) for deep-caisson work at pressures exceeding 3 bar gauge, although definitive studies are needed.
authors.affiliation: Coronel Institute for Occupational and Environmental Health, Academic Medical Center, University of Amsterdam, The Netherlands.
authors.forename: T P
authors.initials: TP
authors.lastname: Van Rees Vellinga
authors.forename: A C
authors.initials: AC
authors.lastname: Verhoeven
authors.forename: F J H
authors.initials: FJ
authors.lastname: Van Dijk
authors.forename: W
authors.initials: W
authors.lastname: Sterk
mesh_terms: D000328:Adult; D000388:Air; D003664:Decompression; D003665:Decompression Sickness / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D004526:Efficiency / Q000502:physiology*; D006304:Health Status; D006371:Helium / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D009426:Netherlands; D009584:Nitrogen / Q000008:administration & dosage*; D009784:Occupational Diseases / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D010100:Oxygen / Q000008:administration & dosage*; D005082:Physical Exertion / Q000502:physiology; D013997:Time Factors
chemical_list: D006371:Helium; C045257:trimix; D009584:Nitrogen; D010100:Oxygen