UV rays are reflected from the ground and water, and scattered by molecules and particles in the air, so even if you are in the shade or using a parasol, you cannot be sure that you will not be exposed to these rays.
Even if you are indoors or in a car, UV rays can pass through glass and reach you.
That is why it is essential to use sunscreen every day.
Picture: Menard's Fairlucent Day Cream White is SPF50, PA++++