There have been a number of anecdotal reports of
rhinitis and
nasal obstruction occurring at altitude. To quantify these reports, we investigated
nasal obstruction and mucociliary transport in a group of healthy volunteers trekking to Mount Everest Base Camp, Nepal, altitude 5,300 m.
Nasal obstruction was estimated by subjective scoring and mucociliary transport was determined by the
saccharin method. Subjective assessment showed that
nasal obstruction was increased on arrival at 5,300 m in 23 out of 54 subjects, unchanged in 24, and decreased in seven (McNemar's test: chi 2 = 7.5; p < 0.01). The median
saccharin time at sea level was 11 min (95% confidence interval (95% CI) 8-17 min) and increased to 60 min (95% CI 27-60 min) on arrival at 5,300 m. Compared to sea level, the
saccharin time was prolonged in 25 out of 33 subjects (McNemar's test: chi 2 = 14.7; p < 0.01), and remained prolonged after 2 weeks at altitude (median 60 min; 95% CI 38-60 min). These results confirm the subjective feelings of
nasal obstruction and show that nasal mucociliary transport times are increased at altitude. The mechanisms of these findings are not clear, but
nasal obstruction may impede breathing and adversely affect performance at altitude.