Sunray, with its thermal energy, UV lights, radiations etc and the skin esp face being exposed to noxious chemicals, vapours, hydrocarbons, various smokes and acidic environment. This age the skin especially facial skin, very quickly.
This give rise to wrinkles, crow's feet, loss of skin volume, loss of water contents, sagging, brown spots and in general, a tired facial skin.
You must:
were hat/sombrero/cover face with cloth - whatever to prevent direct sunrays
avoid thermal energy from sun eg use umbrella, stay in shades, indoors
wear sunblock/sunscreen more than SPF 30
wear sunglasses to prevent prolong squiting that create wrinkles around eyes
wash face with water frequently to wash of chemicals from the air
wash off sweat almost immediately; sweat has salt and other ions.. not good for facial skin