By As I’ve explained before,
UVA– Aging
UVB–Burning are the primary responsible rays.
A famous photograph published in the New England Journal of Medicine illustrates a very important point.
The person in the photograph was a truck driver for 28 years, and one half of his face was directly exposed to UVA rays through the window of his vehicle, while the other half was relatively protected.
This is the answer to the significance of UVA in skin aging and why we need to use sunscreen indoors.