The literature widely acknowledges the deleterious effects of UV radiation on skin health, via production of oxidative free radicals. Consequently, there have been numerous studies on the potential dermatological/anti-carcinogenic benefits of anti-oxidants, such as vitamins C and E, melatonin, green tea, zinc, and selenium. There is, however, a limited amount of literature on the quantity of UV exposure in high-risk settings, such as extreme altitude and equatorial zones. Currently, there is no literature on UV exposure on Mount Everest. Additionally, the efficacy of antioxidants (topical or systemic) has not yet been established in this environment.

This will be an observational study where the principal investigator will collect accumulated ultraviolet exposure at different extreme altitudes during a 6 week period of a summit expedition on the north side of Mt. Everest. Included in the data collection will be patient demographics, time, altitude, temperature, use of anti-oxidants, sunscreen (weighed), and skin erythema (spectophotometer).

9 Mountaineers with intention to summit Everest (1 American, 1 British, 1 German, 5 Australians, 1 Asian-Australian) 4 Trekkers with intention to go to 7000m (2 Americans, 1 Asian, 1 British) 12 climbing sherpas (11 Nepali and 1 Tibetan)

Inclusion Criteria:

• Participants part of the expedition who are willing to wear the monitor, and disclose information of diet/antioxidant supplements and topical sunblock.

Exclusion Criteria:

• Participants who are unwilling to carry the UV monitor or disclose their demographics