The airline passenger: current medical issues.

It is widely accepted that travel by air is unlikely to be a hazard to the vast majority of passengers. However, there are potentially adverse effects of cabin air of poor quality and of the reduced oxygen tension of the cabin environment. There is also the possibility of thrombosis related, at least in part, to the relative inactivity of a long journey. It may well be that the toxicity of the oil additives that are used in aircraft engines should be revisited, and that research should be carried out on the relative importance and potential interactions of the many risk factors for thrombosis that could be enhanced during a long flight. Formal guidelines need to be developed for passengers.