“Under normal circumstances, at sea level, the eye can absorb UVB rays without damage. But with every thousand feet in elevation gain, the strength of ultraviolet rays increases by 5 percent. So at the elevation of Donner Lake, for instance, UVB rays are approximately 30 percent stronger than at sea level.”

“Under normal circumstances, at sea level, the eye can absorb UVB rays without damage. But with every thousand feet in elevation gain, the strength of ultraviolet rays increases by 5 percent. So at the elevation of Donner Lake, for instance, UVB rays are approximately 30 percent stronger than at sea level.”

— Daniel James Brown