Scientists confirm rarefied air poses in-flight problem

More than half of all air passengers experience significant blood oxygen decreases at high altitudes, UK researchers report in the scientific journal Anaesthesia. We take a look at the findings and EU research in the aeronautics field.

The majority of air travellers find that their oxygen saturation drops to a level at which many hospital patients would be prescribed extra oxygen, according to a paper in the May issue of Anaesthesia, the official journal of the Association of Anaesthesiologists of Great Britain and Ireland.

The study by a team of Belfast researchers found that oxygen levels fell by an average of 4% when people reached cruising altitude. A total of 84 passengers, ranging in age from one to 78, had their oxygen saturation levels measured by qualified anaesthetists on the ground and at cruising altitude. From ground-level readings of around 97%, the average fell to 93% at altitude.

“We believe that these falling oxygen levels, together with factors such as dehydration, immobility and low humidity, could contribute to illness during and after flights,” comments Dr Susan Humphreys, anaesthetic specialist registrar.

This has become a greater problem in recent years, as modern aeroplanes are able to cruise at much higher altitudes. Oxygen levels in 54% of those surveyed fell to less than 94% at maximum altitude, she says. Earlier research found that a third of physicians would put hospital patients with these levels on extra oxygen.

Of the total tested, 55 were on long-haul flights lasting more than two hours and the remaining 29 were on short-haul flights. The measurements obtained from both groups were very similar. None of the subjects had severe cardio-respiratory problems and none had to have doctors’ permission to fly.

UK authorities have acknowledged the need for more research into the health effects of flying. “This is the first study to quantify the reduction of percentage oxygen saturation at high altitude during commercial air travel. It demonstrates that there is a significant fall in levels in all age groups during both short- and long-haul flights,” comments Dr Rachel Deyermond, consultant anaesthetist, on the study entitled ‘The effect of high altitude commercial air travel on oxygen saturation’.

At the EU level, aeronautics and space research, under the Research DG’s Sixth Framework Programme (FP6, 2002-2006), has a budget of over €1 billion. Aeronautics research focuses on four main themes: competitiveness, environment, safety and security, and capacity issues. Although no specific funding is set aside for health aspects in the current programme, research exploring better and safer cabin environments is included among the ‘competitiveness’ activities.

The Transport and Energy DG focuses attention on air transport circulation and efficiency, ensuring that Europe’s airline industry remains competitive and ‘open’ and that it respects the ‘European Single Sky’ policy and other regulations.

Legislation such as the Council Regulation (No. 3922/91) for harmonising technical requirements and administrative procedures in the field of civil aviation aims to improve overall aircraft safety levels and operation.