The effects of UV rays on your skin - Planete sante
Radiation
There are three types of ultraviolet (UV) rays: UV-A, UV-B and UV-C.
UV-A
UV-A has a relatively long wavelength and penetrates deep layers of the skin. Excessive exposure to these rays alters the structure of collagen and elastin (two proteins), which causes accelerated aging of the skin and the appearance of wrinkles.
UV-B
UV-B has a medium wavelength (partially blocked by the ozone layer) and does not penetrate beyond the superficial layers of the skin. They cause sunburn in case of too much exposure, but also stimulate the production of melanin, responsible for tanning.
UV-C
UV-C has a short wavelength. These very harmful rays for the skin are completely blocked by the ozone layer and do not reach the surface of the earth.
The tan
Faced with strong solar radiation, the body sets in motion a defense reaction: tanning.
UV-B causes the multiplication of keratinocytes (cells of the superficial layer of the skin). These make the skin more solid and less permeable to radiation. UV-B rays also stimulate the production of melanin (pigments) by melanocytes (skin pigment cells). Melanin has the property of absorbing these rays and therefore of protecting the skin. This process gives the skin the darker shade specific to tanning.
Sunburn
Sunburn is an inflammatory reaction caused by excessive exposure to UV rays. Repeated sunburns accelerate skin aging and are a risk factor for skin cancer (melanoma, etc.).
UV-B rays damage small DNA fragments (called microRNAs) in superficial skin cells. These fragments are released between the cells. Cells close to those damaged identify the phenomenon and stimulate inflammatory cells to initiate the healing process after the death of a cell, and eliminate or clean those whose DNA has been damaged.
Protect yourself !
To enjoy the sun safely, here are some simple rules to follow:
- Do not expose yourself to the most dangerous hours (between 11 a.m. and 3 p.m.).
- Prefer shade.
- Wear a hat and glasses and protect yourself with clothing, if possible anti-UV. Sun creams prevent sunburn but do not protect against melanoma.
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Published in Planète Santé magazine N° 26 - June 2017
