Occupational Aspects of Work in Hypoxic Conditions - The New Recommendation of the Medical Commission of the Union Internationale des Associations d'Alpinisme (UIAA MedCom)

Abstract

More and more persons are exposed to hypoxia while working at altitude, e.g. when working for cable cars or ski areas in the Alps, for business in South America or Asia, as airline crews, or in rooms with reduced oxygen pressure for hypoxia training or fire protection. Unfortunately, the different countries have a multitude of regulations for occupational health and safety concerning hypoxia -most of them with major deficiencies and a significant lack of knowledge about hypoxia and possible specific risks. So far, no national regulation differentiates the different types of hypoxia and the environment, both having significant influence on the specific risk profile of employees and consequences for occupational health and safety.As the world's umbrella body for preventive medicine at altitude / hypoxia, the Medical Commission of the Union Internationale des Associations d'Alpinisme (UIAA MedCom) recently established a recommendation to enable the national bodies to establish knowledge-based pragmatic procedures for occupational health and safety [1]. The most important message is as follows: Any environment with oxygen concentration of 14.0% or more or an altitude of 3,000 m or less is safe for any non-acclimatized person without severe cardiopulmonary disease (<NYHA III or CCS III), without severe anaemia (Hb >10 g/dl) and an exposure limited to a few hours (one work shift). These environments include most alpine cable cars, ski areas, aircrafts flying on long-range distances, most towns or villages where businessmen might go to, and rooms for fire protection. For longer exposure (sleep at high altitude) or higher environments the persons should be acclimatized or exposed for a short time only. Details how to manage health and safety in such environments are given.

Temporary threshold shift after noise exposure in hypobaric hypoxia at high altitude: results of the ADEMED expedition 2011

“…increased pulse rate, hyperventilation, increase of hemoglobin mass, higher capillary density, increased hypoxic ventilatory response, reduced hypoxic pulmonary pressure response etc. [survey in Ward et al (2000), Kupper et al (2010)]. Some mechanisms take effect within seconds (e.g.…”

“…Both effects lasted for at least 1 h after the noise exposure was ended and a complete recovery was reached after a much longer period (3 h). Attitas et al showed in their animal model that a TTS occurred after an isobaric exposure to 6% oxygen (Attias et al 1990), which corresponds to an altitude of about 10,500 m (Ernsting and King 1994;Kupper et al 2010). The finding that acclimatized animals showed significantly lesser hearing impairment supports the thesis of the combined effect of noise and hypoxia (Berndt et al 1978).…”

“…Typically alpine rescue operations take place at altitudes between 2500 and 4000 m (Kupper 2006). At these altitudes, the oxygen pressure is reduced by a third (Ernsting and King 1994;Kupper et al 2010). There are also numerous sites where employees work at even higher altitude rsp.…”

Does Modern Helicopter Construction Reduce Noise Exposure in Helicopter Rescue Operations?

“…Typically alpine rescue takes place at altiudes between 2500 and 4600 m (Küpper, 2006). At these altitudes oxygen pressure is reduced by a third (Ruff and Strughold, 1944;Muller, 1967;Ernsting and King, 1988;Küpper et al, 2010). Hearing is an active, energy consuming process and this energy is provided inside the cochlea over a relatively long diffusion distance.…”

Preacclimatization in hypoxic chambers for high altitude sojourns

“…More and more people try to climb it within 3-4 days and only a minority reaches the summit healthy [1]. Businessmen are another group with limited time or unforeseen trips to high altitude [2]. Principally, correct acclimatization was, is, and will ever be the "gold standard" for any altitude sojourn [3].…”