The benefits and harms of solar radiation for humans have long been the subject of close attention of scientists around the world. It is known that ultraviolet rays
differ in wavelength and are divided into 3 types: UVC - short, UVB - medium length, UVA - the longest. UVC rays do not pose a danger to humans, because. due to the small length of their waves, they do not reach the Earth's surface, being completely absorbed by the ozone layer of the atmosphere. The other two types differ in the degree and nature of the effect on human skin. In addition to the benefits of sunlight, under the influence of which vitamin D is produced in the skin, which helps strengthen bone tissue in the body, there is also a risk of burns, premature skin aging and the development of melanoma (malignant tumor).
To reduce the harmful effects of ultraviolet radiation, sunscreens with PPD and SPF indices are used, which serve as filters that block the rays, preventing them from reaching the skin.skin. SPF filters protect against UV B rays, PPD filters protect against UVA rays, which are
are the most dangerous, since they destroy collagen fibers in the dermis layer, accelerating the aging process, and can also lead to skin cancer. SPF-only products can only prevent sunburn, while PPD and SPF sunscreens provide comprehensive protection against UVA and UVB sun rays. The numbers indicated on the packaging next to the abbreviation indicate the degree of this protection. For example, PPD 8 cream will let 8 times less UVA solar radiation through to the skin, etc. And the SPF number indicates how long you can safely stay in the sun. When choosing a sunscreen, you need to take into account your phototype, which depends on the color of the skin, eyes and hair. Therefore, the lighter the skin, the higher the SPF and PPD should be. The cream should also match the skin type. It should be noted that the higher the degree of protection of the product, the fatter and thicker its consistency. This is suitable for dry skin types. For the most sensitive areas of the face and body with thin skin (eyelids, lips, décolleté), it is recommended to use products with the highest protection index (30-50 units). Also, special attention should be paid to the most protruding parts of the face and body, such as the nose, ears, hips.
In order for sunscreens with PPD and SPF factors to provide the most effective protection, it is recommended to apply them in the same way as regular ones, 20-30 minutes before going outside. During this time, the product will be absorbed into the skin, and it willready for sunbathing.
Sunscreens with PPD and SPF apply to the skin in a thicker layer than regular daily skin care products. For the face, the optimal portion will be equal to the amount of cream that fits on the pad of your finger, and for the body it is about two to three tablespoons.
It should be remembered that even the most persistent sunscreens lose their properties after a certain period of time and as a result of mechanical action. Therefore, it is necessary to renew the cream on the skin during the entire time of exposure to the sun - after about two hours, and also after each swim in the pond.
