Part of the radiation emitted by the sun is ultraviolet (UV). UV radiation is invisible. There are well-documented studies that link it to the occurrence of skin cancers and to the wrinkles, discolorations, sagging that appear on the skin over the years (the greater percentage of aging that occurs on the sun-exposed parts of the body, e.g. face, neck, dorsal surface of the hands and is due to the sun).
To better study UV it has been arbitrarily divided into three sections UVC, UVB and UVA. UVA reaches the earth's surface, has significant intensity from early morning to late afternoon. UVB is filtered to some extent in the atmosphere but reaches the earth – it is most intense between 11:00 and 15:00. UVC is absorbed in the upper layers of the atmosphere and under normal conditions does not reach the earth's surface.
To protect ourselves from the unwanted effects of the sun, we must avoid prolonged activities in the sun without protection (clothes, hat, glasses). Our acquaintances also offer protection sunscreens. These contain filters that either reflect radiation (physically) or absorb it (chemically). It is important that they cover to the greatest extent from both UVB and UVA and even from the longer end of UVA.
It also matters to repeat the application of sunscreen when we are in the sun for many hours, sweat, swim. There is a debate about the possibility that sunscreen use is associated with low vitamin D levels. In Greece, to have normal levels of vitamin D, a few minutes of daily exposure of a small body surface (eg hands) is enough.
H American Academy of Dermatology moreover, he suggests that we should not rely on exposure to the sun to increase vitamin D levels, but on proper nutrition and supplements if these are necessary (eg bedridden people who are always indoors).
Marita Kosmadaki – Dermatologist-Venoretologist, PhD and Scientific Associate of Hospital "A. Composer"
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