1. 1 Danger of icing of the scuba regulator – a neglected risk while diving in mountain lakes Daniel Hothorn (sport student) and Hans-Volkhart Ulmer (Physiologist) Institute of sports science, Johannes Gutenberg-Universität, Mainz, Germany, ulmer@uni-mainz.de 4th international Symposium: “High altitude influence on human performance: science and praxis” – Bohinjska Bela (Slovenia) Sept. 8-13, 2009 ___________________________________________________________ HOTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis

2. 2 Diving in mountain lakes is very attractive. Some special risks are described in literature, however: Especially the problem of decompression during ascent of divers under changed pressure conditions as consequence of the lower ambient pressure in hight, relevant for diving in mountain lakes > 300 m Introduction, aim, methods, results, discussion, final conclusions ___________________________________________________________ HOTHORN & ULMER : Risk of icing scuba regulator, 4th Symposium: Altitude & praxis

3. 3 Introduction, aim, methods, results, discussion, final conclusions ________________________________________________________ HOTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis An other problem is described rarely: The icing of the scuba regulator by water temperatures < 10 °C. The scuba regulator reduces the pressure of the air bottles from 200 bar in two steps until actual ambient pressure for respiration under water Technical instructions: e.g. http://www.divers-travel- guide.com/fileadmin/bilder/pdf/HandbuchSL21.pdf

4. 4 Introduction, aim, methods, results, discussion, final conclusions ________________________________________________________ HOTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis

5. 5 Introduction, aim, methods, results, discussion, final conclusions ______________________________________________________________ HOTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis Icing of the scuba regulator caused by - lower water temperatures (permanent temperatures of 4 - 10 C° in depths > 20 m) - the Joule-Thomson-effect (decompression of gases in a pressure reducer effects cold)

6. 6 Introduction, aim, methods, results, discussion, final conclusions __________________________________________________________ HOTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis Diving in mountain lakes is only marginally included in the basic courses of the great diving associations PADI and SSI, and only referring to the modified decom- pression conditions during ascent. A similar situation was found in nearly all other special courses for diving in mountain lakes.

7. 7 Introduction, aim, methods, results, discussion, final conclusions __________________________________________________________ HOTHORN & ULMER : Risk of icing scuba regulator, 4th Symposium: Altitude & praxis Prevention against fatal accidents by icing: Complete redundant system of scuba regulators and knowledge, how to switch it in case of icing of the primary system, also in darkness

8. 8 Introduction, aim, methods, results, discussion, final conclusions HOTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis Diving equipment with two bottles for com- pressed air and redun- dant scuba regulators ANLINKER, U. & CISCATO, W.: TDI Trimix. 1. Auflage, TDI Germany, 2007, Jüchen www.tdisdi.dewww.tdisdi.de

9. 9 Introduction, aim, methods, results, discussion, final conclusions __________________________________________________________ HOTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis Switching on the 2 nd scuba regulator without look contact (REINTS, 2009)

10. 10 Introduction, aim, methods, results, discussion, final conclusions __________________________________________________________ HOTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis By literature and own experience it seemed for us that the danger of icing of the scuba regulator and the necessity of a redundant scuba regulator is not sufficiently known among divers

11. 11 Introduction, aim, methods, results, discussion, final conclusions _____________________________________________________________________ HOTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis Aim – Evaluate knowledge about the icing problem – Evaluate use of correct equipment against scuba regulator icing – Evaluate the risk of accidents by icing of scuba the regulator In context with divers at a typical mountain lake (Walchensee, Germany, 802 m)

12. 12 Introduction, aim, methods, results, discussion, final conclusions ______________________________________________________________ H OTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis Methods – Inquiry with a special manual of 30 divers at the Walchensee (802 m) – Interview with 3 regional therapeutic recompression centres

13. 13 Introduction, aim, methods, results, discussion, final conclusions _____________________________________________________________ H OTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis Results Inquiry of the divers: - Most of them knew the necessity of special decompression procedures - but only half of them knew the danger of icing of the scuba regulator and used, in consequence, a complete redundant regulator system - Only a minority had passed a special course for diving in mountain lakes

14. 14 Introduction, aim, methods, results, discussion, final conclusions _____________________________________________________________________ HOTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis Interview with decompression centres: Nearly all serious accidents of divers in mountain lakes were caused by iced scuba regulators

15. 15 Introduction, aim, methods, results, discussion, final conclusions __________________________________________________________ HOTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis Discussion This study underlines the often neglected importance of icing of scuba regulators during diving in mountain lakes (definition > 300 m). - Neglected in the curricula of basic courses - Neglected by divers to join special courses for diving in mountain lakes - Neglected by divers to use redundant regulator systems and to train how to use in case of icing under realistic conditions

16. 16 Introduction, aim, methods, results, discussion, final conclusions __________________________________________________________ HOTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis Final conclusion - In every basic course for divers the risk of icing of the scuba regulator should be underlined, combined with the necessity to join special courses for diving in mountain lakes. - In these special courses the necessity to use redundant regulator systems should be explained and it should be trained during diving in darkness, how to use them in the case of icing of the primary system.

17. 17 Introduction, aim, methods, results, discussion, final conclusions __________________________________________________________ HOTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis Thanks for Copyrights: Wilk reints (sheet 9) www.dir-m.com"www.dir-m.com H. Dederichs (sheet 8) www.tdisdi.dewww.tdisdi.de

18. 18 Introduction, aim, methods, results, discussion, final conclusions __________________________________________________________ HOTHORN & ULMER: Risk of icing scuba regulator, 4th Symposium: Altitude & praxis The end