Photoprotection means protecting yourself from the sun. Most people believe that sunscreen (or sunscreen or sunblock) is enough to give us that protection, but that's not true, sunscreen is not synonymous with sun protection.
The sun emits various types of radiation, waves, of varying lengths. Each of these wavelengths will determine the consequences of this radiation to humans.
Four are the main types of radiation that reach the Earth's surface:
Ultraviolet B (UVB) - virtually imperceptible light, responsible for sunburn, skin tanning, darkening of spots and most skin cancers. This radiation is most intense near noon, in the summer and in the tropics;
Ultraviolet A (UVA) - also little perceived, represents 95% of the light that comes to Earth and is responsible for skin aging, tanning of the skin, darkening of spots and some skin cancers. In comparison to UVB, this radiation varies very little throughout the year, the day and the globe;
Infrared (IR) - this red-toned light is responsible for part of the perception of luminosity and heat that we have under the sun. It appears to be associated with darkening of some types of spots;
Visible light - these are the various wavelengths within this group that allow us, mainly, to distinguish colors. There is controversy about its potential to stain the skin.
It is very important to note that clouds are not capable of blocking, mainly, UVA and UVB radiation, despite the decrease in light and heat on rainy days.
So now that we know why the A and B radiations are the most damaging to our health and what are the times we are most exposed to each of them, let's understand a bit more about the products that the pharmaceutical industry offers us.
The sunscreens have the FPS (or SPF) symbol on the packaging, which means " Sun Protection Factor ". This factor should serve to standardize the different products, facilitating the life of the consumer, but in practice this is not what happens. The FPS is based on sunburn, ie only UVB (see above), and mainly determines the exposure time we can have without getting pink skin.
For example, imagine a light-skinned person who, without any skin product, starts to have rosy skin after 10 minutes of sun exposure and another, with dark skin, that starts to turn pink after 20 minutes of the same exposure. If they apply a SPF 30 sunscreen, theoretically the light skin can be 30 times 10 minutes (300 minutes) and the brown skin 30 times 20 minutes (600 minutes) until they begin to turn pink. That is, the lighter the skin, the less protection of the same sunscreen.
In addition, each SPF has a percentage of anti UVB protection. An SPF 30, for example, protects about 96% of UVB rays and a SPF 50, 98%. So, even being within the timeframe explained above, the protection will never be 100%. Knowing this makes it easy to understand why products with SPF above 50 probably do not bring any extra benefits.
Another fact of extreme importance is that to determine the FPS, the tests are done with an amount that hardly a person can use. This would be, for a 70kg adult, in a single day at the beach, for example, a 60ml bottle of sunscreen. In practice, we use only 25% to 50% of that amount!
And the UVA? This radiation, often neglected by not burning the skin, is also associated with skin cancers. The biggest evidence of this is the fact that this disease is becoming more common, even with the advent of sunscreens. In addition, UVA has great aesthetic importance, since it is the radiation responsible for the aging of the skin and, like UVB, for its pigmentation.
The great difficulty of the blockers is in protecting us from this radiation. The tests can not tell us how protected we are, so there is no standardized factor to indicate this protection. Product labels usually indicate "broad spectrum protection", "PPD" (followed by a number) or a sequence of up to 3 crosses (+++), in an attempt to identify how much this product protects us from UVA. But make no mistake, a PPD considered high or a "+++" indication may even mean that the product offers anti-UVA protection, but we are not sure exactly what protection we have.
Everything that has been explained so far does not mean that we should not use sunscreens, on the contrary, they are very useful, but we must know that the use of protectors as the only method of sun protection, will do more harm than good, since good protection anti UVB and consequent absence of sunburn, may leave us more time in the sun, exposing us for much longer to the UVA.
So it is imperative that, in addition to generously applying a sunscreen, reapplying it every 2 hours or every time the skin is wet, we should always be in the shade and with broad-brimmed hats and thick, preferably dark, even in times of less intense sun! And know that a wet fabric protects less than a dry one. Nowadays there are several brands of hats and clothes of light fabrics, but of closed weave, that allow a reasonable protection even when wet.
Such care should be redoubled in those who have skin blemishes and diseases that may be aggravated by the sun, such as lupus. In such cases, one should pay close attention to the light reflected in the sand, water and even snow!
To choose the ideal sunscreen we have to have a notion of how they are composed. Sunscreens contain active principles that can be divided into chemical (substances that absorb or neutralize UV) and physical (substances that make a mechanical barrier, which is intended to physically prevent radiation from entering the skin cells).
In each commercial product, there are different combinations of chemical and physical filters, but the latter are the most important for those who are concerned with protecting against UVA too - the most common are zinc oxide and titanium dioxide.
In addition to looking for products containing the substances mentioned above, consider the type of skin and the type of exposure that is intended to have. For example, thicker and greasy products form a thicker layer and do not come out so easily in the water, being the best choice for children and sportsmen, but can cause acne in those who have oily skin. Gel products, on the other hand, do not worsen acne, but leave with extreme ease with minimal sweating and hardly contain the physical filters in your formula.
Finally, after all this explanation, you may wonder if the sun is bad. The answer is absolutely no! The sun is critical to our health and well being, and especially to produce vitamin D that will fix the calcium in our bones. But in order to have that, the quantity required is relatively small. For example, getting under the early morning or late afternoon sun with just your back, arms or legs exposed for 15 minutes, 2 to 3 times a week may be enough.
