Low concentrations of formaldehyde in bronchial asthma: a study of exposure under controlled conditions.

The rapid ascent to 4560 m caused minor symptoms of acute mountain sickness such as headache, nausea, and insomnia in all participants. We did not, however, find any influence of this short term exposure to high altitude on the morphology of the red cells. Our results are in contrast to the morphological changes observed by Rowles and Williams at a similar altitude (4600 m) during an expedition with ascents to 6200 m and 7200 m between blood samplings.2 We cannot exclude the possibility that the ascents to the higher altitudes had an influence on the morphology. More probably, however, those morphological changes, which developed gradually over five weeks, reflected adaptive changes to high altitude, such as the increased erythropoiesis regularly observed at high altitude, rather than a short term effect. Our results indicate that changes in red cell morphology can be ruled out as a pathophysiological factor in acute mountain sickness.