Our skin, sunrays, and the effects of sun exposure
The skin is the largest organ of the human body. It consists of three layers (Figure 1): (a) the epidermis, which is the outer layer, is composed of keratinocytes and protects the skin and consequently the body from harmful environmental factors, (b) the dermis, or mainly the skin, which is the intermediate layer, consists of collagen and elastin fibers giving the skin elasticity and (c) subcutaneous fat, or subcutis, which is the deep layer whose function is to support the overlying tissues.
Our skin is constantly under the influence of environmental factors. Among them, special emphasis should be given to solar radiation, specifically ultraviolet, which causes immediate and long-term harm.
Ultraviolet radiation is distinguished into ultraviolet rays A (UVA), B (UVB) and C (UVC).
UVA radiation has a long wavelength and penetrates the epidermis reaching the dermis (Figure 2). Long-term exposure causes fragmentation of the collagen and elastin fibers of the skin, thus leading to reduced skin elasticity resulting in photoaging. Photoaging acts as a basis for the development of skin lesions, some of which are malignant.
UVB radiation has a short wavelength. It interacts with the skin without penetrating it (Figure 2), causing immediate surface damage, the so-called sunburn. Sunburn is manifested by painful erythema in the areas exposed to the sun or by simultaneous blistering in its most severe form.
Ultraviolet C rays are absorbed by the ozone zone. They do not reach the surface of the earth and thus do not interact with our skin. Imminent ozone depletion is unlikely to change this parameter.
It is important to prevent both the immediate (sunburn) and long-term (photoaging, skin cancer) effects of sun exposure.
The best prevention is to avoid exposure to sunlight, especially during the summer months and during the noon hours.
The use of protective equipment such as hats, sunglasses and light-colored clothing that cover as much of the skin as possible is also necessary.
Regarding the use of sunscreens, especially in our country, it must be daily regardless of the season, the amount of sunshine, or the daily habits of the person. This is documented by the ability of UVA radiation to penetrate the clouds as well as refractive media (windows, car glasses) to have a detrimental effect indoors or even in the shade.
Use sunscreen twice a day, in the morning and at noon, regardless of gender and age. The application should be done about fifteen minutes before sun exposure. In case of prolonged exposure (eg on the beach), the sunscreen should be renewed half an hour after exposure and after any contact with water.
It is important to know that sunscreens do not allow for unlimited sun exposure. This should be kept under control regardless of their use.
The characteristics of a suitable sunscreen for the face are the following:
– Total sun protection (against UVA and UVB)
– Sun protection index (SPF) greater than 30
– Not greasy (preferably in the form of a cream or gel) so that it is not itchy (comedones are a common cause of acne)
– Does not contain pigments (which may be allergenic)
