Besides wearing Sun-protective clothing and applying sun screen, you can reduce your Sun exposure by avoiding being outside around noon, i.e., shifting outside activities to the early morning and evening when UV radiation is less strong because the rays have a longer path to travel thru the atmosphere. In addition, you can reduce your UV exposure by hiking at low elevation. Note that your exposure is higher in pristine air like in a National Park than in the polluted air of a Mega city, and that seeking shade fails to save you from a sunburn.