Sun burn, burns, allergic reactions, different weeds such as poison ivy, and many more things this is just the ones i can think of right off hand if this is for a medical reason i would suggest webmd.com
mystery historyMystery, history
Mystery, protohistory, prehistory, blistery, storymystery
the pigment in your skin
Dry skin
An allergy to mango skin could do it. The mango plant is related to poison ivy, oak, and sumac. It has the same oils in the leaves and skin of the fruit, though they are much less concentrated. It usually takes 12 to 24 hours for symptoms to appear. If you think this could be what caused your rash, be sure to remove the skin of the mango completely before eating the fruit in the future.
its dry skin
what causes skin full tickness
pigments
The same thing that causes any human to have light skin, the degree of melanin in the skin.
UVA (which causes tanning) also causes skin aging, eventually giving skin a tough leather like texture. UVB (which causes burning) also causes skin cancer, frequently melanoma an aggressive cancer that sometimes metastasizes throughout the body.
The ozone has a harsh affect on skin. It penetrates the skin. It also causes cancer.
UV radiation is harmful to skin. It causes skin cancer.