Ultra-Violet radiation consists of UVA, UVB and UVC rays, with UVC being the most harmful. Fortunately, UVC rays are filtered to a large extent by the ozone layer of the atmosphere.
UVA RAYS – ageing rays
UVA rays are closely associated with skin ageing. They have a longer wavelength than UVB and are therefore able to penetrate deeper into the skin, right through to the dermal layer that contains connective tissue. UVA rays cause structural damage to these collagen and elastin tissues, causing the ‘scaffolding’ of the skin to collapse, giving rise to wrinkles and sagging skin.
These ageing UVA rays are equally strong from sunrise to sunset and are present throughout the year. Surprisingly, they are strongest when they are at an angle to the earth, approximately between 08h00 – 10h00 and 14h00 – 18h00. They are also able to penetrate through glass. This explains why our hands, for example, will develop age spots from having them on the steering wheel of a car for extended periods of time.
UVB RAYS – burning rays
UVB rays, on the other hand, are closely associated with burning. They have a far shorter wavelength and travel a shorter distance into the skin compared to UVA, inflicting most of the damage to the outer epidermis. UVB rays are 1000 times stronger than UVA rays in intensity and are more cytotoxic and mutagenic than UVA rays, directly modifying cell DNA and are therefore the major cause of skin cancer.
These burning rays are strongest during the summer months, especially from noon to 15h00. UVB rays do not readily penetrate through glass.
85% of all skin ageing is caused by exposure to the sun, with most of this damage complete before the age of 20. This makes sunscreen application during the teen years crucial for the prevention of skin ageing.
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The Vitaderm Team