Uvb Radiation: The Importance Of Sun Protection

First of all, let’s understand what skin is. The skin is the largest organ in the human body and represents 16% of our weight. It performs essential functions such as blood flow control, thermal regulation, and protection against external threats. It is made up of 19 million cells, 625 sweat glands, and 19,000 nerve cells.

The skin is the first physical and immunological barrier against the attacks that the body suffers from the sun. And what is tanning? Tanning is nothing more than a defense of the skin against radiation . With the “attack” of the sun, our body produces a stimulus for the production of melanin (pigment with photoprotective function) in an attempt to filter ultraviolet rays and protect our cells against damage. Being a dark pigment, the skin darkens or tans.

Dark-skinned people are more protected due to the greater amount of accumulated melanin , so the skin rarely turns red from the effects of ultraviolet (UV) radiation. The most important difference between these UVA and UVB rays is that UVA penetrates deep into the skin, while UVB reaches only the most superficial layer (see infographic below) , and the attention they deserve also plays an important role in health. .

Upon reaching our skin, UV (ultraviolet) rays penetrate deeply and trigger immediate reactions, such as sunburn.

They also cause reactions over time due to the cumulative effect of radiation during life, causing the skin to age and causing cell changes through genetic mutations that predispose to skin cancer.

Types of solar radiation

UVA rays

UVA radiation is constant throughout the year and penetrates deep into the skin, being the main cause of photoaging , and this type of radiation does not contribute to skin cancer.

The intensity varies little throughout the day, but is more intense before 10 am and after 4 pm – PENETRATES EPIDERMICALLY

  • Although it seems more harmless, providing a beautiful tan (stimulates melanin), these are the rays responsible for skin aging (changes elastic and collagen fibers, causing wrinkles, loss of elasticity and blemishes) and melanoma cancer, just at the reach the deepest layer of the skin.
  • It also induces the production of spots on the skin (chloasma / melasma). Pregnant women or those who use hormones and contraceptives are the most affected.

UVB rays

UVB rays

Its incidence increases significantly during the summer, especially during the hours between 10 am and 3 pm. UVB rays penetrate the surface and cause sunburn . It is the main source of the cellular changes that predispose to skin cancer.

UVB rays are responsible for skin burns, that is, those red and burned spots that appear when we go to the beach without sunscreen.

The long UVA does not cause this surface reaction , however, are able to penetrate deeper layers. Excessive exposure to these rays, over time, damages the skin and promotes the development of cancer.

The use of sunscreen

The use of sunscreen

To protect ourselves from the harmful effects of UV rays, we must be careful. The first is to avoid sun exposure between 10 am and 3 pm , a time when the sun is strongest. In addition, when practicing outdoor activities or spending the day at the beach, we have to protect ourselves with hats, sunglasses and apply sunscreen.

If you have oily skin, check out our article on sunscreens for oily skin .

The sunscreen acts as a chemical barrier that absorbs UV rays, preventing skin damage . An opaque protective layer on the body also acts as a physical barrier, reflecting sunlight. When buying a sunscreen you should look for products that offer protection against UVA and UVB rays, and choose an SPF that is suitable for your skin type.

Sun Protection Factor

SPF is an acronym with the initials of actor for Sun Protection, which indicates the degree of protection offered against sunburn. When someone uses a filter with SPF 15, for example, it means that it will take 15 times longer to redden than if the product had not been applied . In other words, you are 15 times more protected than if you had nothing.

But be careful, as explained above, both UVA and UVB rays damage the skin, contrary to what those who expose themselves to the sun before 10 am and after 4 pm (UVA) imagine, who believe that it does not hurt because they do not burn. Therefore, as the SPF refers only to the degree of protection against UVB radiation and there is no consensus to classify protection against UVA radiation, the ideal is to opt for products that inform, on the packaging, that they offer protection both UVA as UVB . The effectiveness depends on the amount applied and the exposure time.

Myths and truths of the sun protection factor SPF

woman covering face sun

  • The sun protection factor (SPF) of 15 is considered broad spectrum of ultraviolet rays from UVA and UVB rays, and blocks 93% of radiation. Above that, the difference is small. A sunscreen with SPF 30 blocks 96% of radiation and SPF 60 protection reaches 98%.
  • The product should be applied at home, and reapplied throughout the day, every 2 hours , if there is too much sweating or prolonged exposure to the sun.
  • Reapply sunscreen after prolonged immersion in pool or sea water.
  • It is necessary to apply a good amount of the product, which is equivalent to one teaspoon on the face and three tablespoons on the body evenly, so as not to leave any area unprotected.
  • The sunscreen should be used every day , whether it is cold or cloudy, because the UV rays pass through the clouds.
  • You should be even more careful in snow, sand, grass and water, because they reflect sunlight and intensify it even if you are in the shade.
  • The eyes should also be protected with the use of sunglasses . Each year, approximately 3 million people suffer vision loss due to UV-related damage – such as photoconjunctivitis and cataracts.

How the Sun Helps Health – Vitamin D

Health - Vitamin D

Here we are going to explain the symbiosis of the sun and vitamin D, but for more information we recommend that you look at our article on vitamin D: Properties, Benefits and how to get it.

  • Vitamin D can be produced by the human body, but it depends on the interaction of UVA and UVB rays. Only 10% of the necessary amount of vitamin D is achieved through food, such as cod, salmon, milk and egg yolk.
  • The lack of vitamin D increases the risk of diseases such as rheumatism, arthritis, osteoarthritis, and especially osteoporosis. Other diseases, such as breast cancer, cervical cancer, prostate cancer, diabetes and cardiovascular disease, are also related to a lack of vitamin D. Check this other article with the problems that vitamin D deficiency generates in our health .
  • The time of exposure to the sun for the production of vitamin D is 15 to 20 minutes, at least three times a week. Exposure of the arms and legs is enough to increase vitamin D levels. In other areas, wear appropriate clothing and sunscreen.
  • The use of sunscreen and the time of sun exposure are controversial. Different studies show that the regular use of sunscreen does not affect the production of vitamin D. Others say that a protection factor above 8 already prevents the production of the nutrient for the skin. People with very fair skin, who are at increased risk of skin cancer , always wear sunscreen and only sunbathe three times a week, but only on their arms. Orient yourself with your doctor.
  • People with darker skin have reduced ability to synthesize vitamin D and therefore must be exposed to the sun more frequently .


Over the years, the skin, like all other organs of the body, undergoes changes and aging. These changes lead to loss of elasticity and radiance, there are wrinkles and sagging. But it is not only chronological aging that causes the appearance of changes in the skin over the years. External factors such as stress , smoking and, especially, solar radiation, influence and accelerate the aging of the skin , causing its appearance to change with the appearance of spots , roughness, wrinkles and other early signs of aging.

Sun-damaged skin shows loss of elasticity, wrinkles, dark or light spots, and surface changes, and can become rough. Aged skin due to the natural deterioration of the body appears thinner, flaccid, with little elasticity and has fine wrinkles, but no blemishes or changes in its surface.

Prevention and treatment of photoaging

The best way to prevent photoaging , again, is to use sunscreen . The sooner it is done, the better the person will look. If you have already reached 30 you should start as soon as you can, because at that age the biological performance begins to decline. Fortunately, today we know that we can delay the effects of time , protecting the skin from its most implacable enemy : the sun.

The aesthetic treatments are modernized every day. Various techniques are being used, among which peels stand out . Innovations in the aesthetics of the area still involve sophisticated equipment and various massage techniques, not to mention the constant release of natural and chemical cosmetic lines .

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Kathie Sand always saw the world of beauty as the terrain on which to build her professional career, a goal that was clear to her when she was only 15 years old. Her great concern to expand knowledge led her to settle in Paris where she studied hand in hand with the best beauty professionals and with the most advanced techniques for skin care.

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