An observational study of personal ultraviolet dosimetry and acute diffuse reflectance skin changes at extreme altitude.
OBJECTIVE
To determine the level of UV radiation at extreme altitude and to assess the effect it has on the skin.


METHODS
Fifteen expeditioners and 10 Sherpas were assessed during a climbing expedition on the north side of Mt Everest (8848 m). UV exposure measurement and diffuse skin reflectance spectrophotometry were performed at the beginning and end of the expedition.


RESULTS
Over the course of the expedition, the expeditioners and Sherpas received a median dose of 93.6 (interquartile range [IQR], 61.0-102.8) and 102.5 (IQR, 72.2-117.8) minimal erythemal doses (MEDs) of UV radiation. The maximum dosage exceeded 106 ± 1.4 MEDs. Using reflectance spectrophotometry, expeditioner and Sherpa melanin-hemoglobin increased by 83.6% (IQR, -1.5 to 89.8%) and 24.7% (IQR, -22.4 to 61.5%) for exposed skin, respectively. The amount of subcutaneous lipid-water decreased by a factor of 196.6 (IQR, 52.1-308.4) and 46.7 (IQR, 1.8-1156.5), for expeditioners and Sherpas, respectively.


CONCLUSIONS
This expedition's participants received massive doses of UV radiation during their time at high altitude. In many individuals this was similar to the annual exposure of northern European office-workers (100 MEDs). Diffuse skin reflectance spectroscopy revealed considerable subcutaneous lipid loss, skin dehydration, and increased melanin in keeping with these levels of exposure.
Emergency Department, Sunnybrook Health Sciences Center, North York, Ontario, Canada. Electronic address: ivy.cheng@sunnybrook.ca.
Ivy
I
Cheng
Alex
A
Kiss
Lothar
L
Lilge
D000328:Adult; D000531:Altitude; D001412:Bacillus subtilis / Q000528:radiation effects; D005101:Expeditions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009051:Mountaineering; D009390:Nepal; D011446:Prospective Studies; D011874:Radiometry; D012867:Skin / Q000528:radiation effects*; D013053:Spectrophotometry; D014466:Ultraviolet Rays / Q000009:adverse effects*; D055815:Young Adult
attenuation; diffuse reflectance; extreme altitude; mountain medicine; skin; spectrophotometry; ultraviolet exposure