I sunscreens or cosmetics Solari were created to provide protection against radiation damage. These shall not exceed the MED , which is the lowest dose that provides Erythema ( Minimal Dose Erithematic ). If the MED is not exceeded, the body can slowly provide for the synthesis of pigments that ensure the proper protection.
E 'can protect themselves in a natural way , trying to pay attention to certain factors. Much influence in fact have the latitude, altitude, the reflectivity of surfaces and terrain. For Tropics sun exposure is more dangerous because the radiation reaching the earth faster. In the mountains instead, where the atmosphere is clearer, the radiant energy increases and the radiation is stronger. However, the snow reflects much solar radiation, about 70%. The sand reflects about 20% of the total radius, while the water only 10% (that's why you tan more quickly on the sand or water!).
I sunscreens instead are specific substances that are spread on the skin and a chemical that consist of molecules that can absorb the radiation and then release it as heat, avoid that the skin remains in contact with the rays. The solar
must therefore be very stable, should not be irritating, to be effective for all types of UV radiation and have high absorbance value. L ' Absorbance screening identifies the power of the filter.
The protection factor SPF is identified as the ratio between the minimum dose erythematous skin protected by sunscreen and minimal erythema dose of unprotected skin. Most important is the time of sun exposure, which are closely related. The relationship between the two exposure times provides a mathematical calculation of the protection factor.
Statistics on Sun Protection Factor also depends heavily on technical factors, such as lamps used, the thickness of cream spread, the type of emulsion, the quality of his fat phase, and so on. There are several conventional methods and scales, but the most used is that COLIPA ( European Association of Cosmetic Industries ).
The various methods differ in subject, amount of product per unit area, measurements of the MED-ray light source, UV exposure increases, the calculation of the protection factor, the reference standard.
Sunscreens can be divided into filters Chemical (UVA and UVB) and Physical filters.
I chemical filters are: benzophenone derivatives and derivatives Benzoilmetano (UVA), amino acid derivatives, derivatives of salicylic acid, derivatives of cinnamic acid, derivatives of camphor (UVB).
I Physical filters are titanium dioxide, zinc oxide, talc and kaolin.
may also be used adjuvant substances, which have weak filtering action, but that combined with solar filters can improve the effect. These are extracts Buckthorn, Cascara, Chamomile, Hypericum, Helichrysum, Shea Butter, Avocado Oil, Sesame Oil, Rice, Bergamot.
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