Ivy Cheng1, Alex Kiss, Lothar Lilge. 1. Emergency Department, Sunnybrook Health Sciences Center, North York, Ontario, Canada. Electronic address: ivy.cheng@sunnybrook.ca.
Abstract
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.
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.