High altitude. UV intensity increases 4 5% for every 1000 of elevation. At 10,000 feet you can be exposed to 50% more UV. Add reflection off snow and you've got serious protection needs Broad Spectrum UVA UBV protection helps prevent long term sun damage Active Durability. With added UV intensity, mountain sports athletes need sunscreen formulations that wont fade in harsh conditions. Chemical sunscreens expire after UV exposure mineral oxide sunscreens do not. Careful choice of sunscreen active ingredients is essential. High and Dry. Higher elevations have very dry air. Your skin needs extra protection against moisture loss. Sweat Resistance. Running around the mountains can work up a heck of a sweat, even in the winter. If your sunscreen melts like snow in the Mojave youve got eye sting and sunburn.