Depending on how acting filters can be physical or chemical.

• Physical filters: are substances impervious to sunlight, creating a screen in areas where it has been applied and reflects light. Prevent the passage of the three types of radiation: ultraviolet, visible and infrared. The most commonly used are zinc oxide, titanium dioxide and mica.
• Chemical filters: they absorb solar ultraviolet radiation. Some of those used are the PABA (para-amino benzoic acid), cinnamic acid, sulfonic acid, camphor, benzophenone and dibenzoylmethanes.

To quantify the filtering capacity of sunscreen is used the so-called Sun Protection Factor: a number that measures how many times it can be exposed to the sun to produce the same redness or erythema that if he had not used the cream sunscreen. That is, if not for the skin starts to turn red (erythema), the first day that we must take the sun 10 minutes, using an SPF cream 5, it will take 50 minutes.

The SPF indicates the time that we expose to the sun without risk of burns. The higher the SPF, the higher the protection from sunlight.

Sunlight breaks down upon reaching the earth’s surface in various types of radiation according to wavelength, are classified as ultraviolet radiation, visible radiation and infrared. In turn, ultraviolet radiation can be UVC, UVB or UVA. UVC rays have the shortest wavelength, are the most energy and therefore more capable of burns, but are retained by the ozone layer. Thus the reduction or the existence of holes in the ozone layer is so dangerous.

UVB rays as well as the heating effect (which causes the redness or Erythema of the skin when exposed to sunlight), penetrate the epidermis and stimulate the melanocytes (skin cells that produce melanin, the substance that gives the brown color to the skin).

UVA rays are the most penetrating the skin and are the cause of skin aging and melanoma (skin cancer).

Besides the type of radiation, it is necessary to know the factors influencing the action of sunlight on the skin. Thus, we must bear in mind that, how much higher the geographical area where we are, the more intense the exposure, the obliquity of the rays of the sun and the earth also influences, depending on the season, time of day and the latitude of the geographical area. The climate also influences, as the rain and clouds absorb some radiation. Also the type of area where we are, because the snow reflects up to 85% of the rays, and the dry sand to 17%.

To guard against such harmful effects, the human skin with the production of melanin, a substance that prevents most harmful solar radiation to penetrate the skin. Melanin is what gives the dark color to the skin and its production is stimulated by the effect of sunlight or chemicals. The number of cells that produce this substance varies according to skin types. People is highest in blacks, and lowest in whites, and among them, the lighter skins are the most susceptible to the effects of the sun.

1 .- The protection with the clothes:
It has the advantage of being user friendly, safe and affordable cost. Umbrellas, hats, sunglasses and shirts and integration should be the least of all children before exposure to sun, knowing well that if there are three factors that influence the transmission of ultraviolet rays.

* Moisture: wet dress and stops UV least one dry.
* Color: dark color ensures protection against ultraviolet rays and visible light, a light color infrared protection, ie heat.
* The material and web groso: efficiency decreases from the jeans, the bright polyester, cotton and synthetic materials.

2 .- The sunscreen products.
The protection level of the skin exceeds the cosmetology field for entering the preventive medicine. This insured sunscreen preparations formed by the association of active principle (filters or screens), solubilized or dispersed in a carrier.

a. – How sunscreen products are presented?.
For best absorption, ultraviolet A and B are associated with various filters.

b. – solar screens: they are constituted by opaque inert powders that ensure physical protection and diffusion reflection of ultraviolet rays and visible light. Although its spectrum is broad, its effectiveness depends on their concentration can not be very high considering giving it a hazy appearance, poor acceptance cosmetologist. They are used mainly in the high protection sunscreen products associated with sunscreens.

c. – The excipient: not only allows the extension of the active ingredients in an even layer of the skin, but also involved in the adhesiveness and the prolonged action in time and especially water resistance and breathability.

d. – The anti-free radical agents that are in vogue. Such as vitamin E and C, beta carotene, selenium, among others.

3 .- The health education.
The family education and prevention advice should not only be disseminated by the media but also by all professionals responsible for health and education of people .. From childhood is to be planned exposure to the sun, to strike a balance between beneficial and misery, without disrupting the outdoor activities, developed particularly at that age.

Preventing the incidence of skin cancer, necessarily, by reducing sun exposure and prevention and the protection and appropriate clothing recommended screens and filters. From the first years of life

TEN SIMPLE TIPS FOR SOLAR EXPOSURE.
1 .- To know the personal sensitivity to sun exposure and make progressively.
2 .- Avoid exposure between 12 and 16 hours and not ever stay at the beach all day.
3 .- Enforce protective clothing for children especially
4 .- suspicious of reflection on the floor (water, sand, snow)
5 .- To distrust the false security offered by a cloudy sky or a windy day.
6 .- Fear to heat stroke and sun stroke in a child exposed to intense sun.
7 .- Do not forget to protect your eyes: visor, sunglasses.
8 .- Never exposed after application of scented products or when we are ingesting a drug suspect.
9 .- Apply sunscreen regularly effective products designed not to increase the total number of hours of exposure or tanning promote intense, but to allow for reasonable safe exposure.
10 .- As parents, we lead by example; photoprotection measures will then be followed more easily understood by children and adolescents.