Comparison of argon and air as thermal insulating gases in drysuit dives during military Arctic diving equipment development tests

Introduction: It is vital to protect divers from the cold, particularly in Arctic conditions. The insulating gas layer within the drysuit is crucial for reducing heat loss. The technical diving community has long claimed the superiority of argon over air as an insulating gas. Although argon is widely used, previous studies have shown no significant differences between the two gases. Owing to its lower heat conductivity, argon should be a better thermal insulating gas than air. Methods: The study aimed to determine whether argon is beneficial for reducing heat loss in divers during development of military drysuit diving equipment in Arctic water temperatures. Four divers completed 14 dives, each lasting 45 minutes: seven dives used air insulation and seven used argon insulation. Rectal and eight skin temperatures were measured from which changes in calculated mean body temperature (MBT) were assessed. Results: There was a significant reduction in area weighted skin temperature over time (0-45 minute) on air dives (Delta T-skin = -4.16 degrees C, SE = 0.445, P < 0.001). On argon dives the reduction was significantly smaller compared to air dives (difference between groups = 2.26 degrees C, SE = 0.358, P<0.001). There were no significant changes in rectal temperatures, nor was a significant difference seen between groups. Conclusion: Compared to air, argon may be superior as a drysuit insulating gas in Arctic water temperatures for some divers. Argon used as insulating gas can make diving safer and may diminish the risks of fatal diving accidents and occupational hazard risks in professional diving.