We have put together answers to the most urgent questions about sunbathing for you – our sun guide from sun protection to UV radiation:

Is the sun generally unhealthy?

No, because sunlight is good for body and mind. The light stimulates the production of messenger substances in the body that make you active and happy. Sunlight stimulates the metabolism, the heat expands the vessels, the blood can flow faster and the cells are better supplied with oxygen. Sunlight is even good for visual acuity, says Frank Schaeffel from the Center for Ophthalmology at the University Hospital in Tübingen. In children who spend two hours outdoors each day, the likelihood of myopia drops by more than half. The simple reason: During the day it is up to 200 times brighter outside than in closed rooms.

For the Vitamin D Production UV radiation is also indispensable. The body produces its own vitamin D when the sun’s UV rays hit the skin. Vitamin D prevents the calcium level in the blood from falling. It is also involved in the metabolism of calcium and phosphate and therefore has an indirect part in the bone structure. Studies suggest that vitamin D can also protect against pathogens. About 15 to 20 minutes of sunlight a day on the face and hands are enough to produce the vitamin. Skin pigmentation, age and intensity of solar radiation also play a role.

How do the UV rays affect the skin?

Short-wave UV-B radiation in particular is highly biologically active. Although it produces the tan that is so popular, it also causes mutations in the skin cells. UV-B rays have a very high energy and penetrate into the outer layers of the skin. There they can cause the genetic material of the cells to change or break. As a result, the cell can no longer function properly and, in the worst case, becomes a cancer cell.

For a long time it was believed that only UV-B rays damage the skin. It was only in the 1990s that the effects of UV-A radiation were pointed out. It has longer waves than UV-B radiation, so it penetrates ten times deeper into the skin and penetrates the middle layer of the skin – the so-called dermis. There it rarely destroys the genetic material, but it can damage the skin’s collagen. Result: The elasticity of the skin decreases, it becomes limp, leathery and wrinkled. According to studies, the sun is 90 percent responsible for skin aging. Over time, the tan, which is perceived as beautiful, leads to very unsightly wrinkles. And not only that: According to what is known today, the development of black skin cancer, malignant melanoma, is promoted by excessive UV-A radiation. UV-A radiation also promotes skin allergies.

A bath in the sun is only recommended with adequate sun protection. (Photo: CC0 / Andrea Piacquadio / Pexels)

How good is my skin protection?

To a certain extent, the skin can defend itself against UV radiation alone. It immediately forms urocanoic acid, which lies on the skin like a protective film. However, this only works as long as the skin remains dry and the protective film is not washed off when bathing in the sea or in the swimming pool. As sun protection, the skin also gets a “thick coat” – a cool layer or cornea. However, this takes two to three weeks.

The tan, which is made from the body’s pigment melanin, is nothing more than a protective mechanism for the skin. The pigmentation is stimulated by UV-B rays. About two to three days after sunbathing, a long-lasting tan becomes visible, which deepens with each additional stay in the sun. The same applies here: this self-protection is developing slowly – and for light-skinned types that get little color, the skin’s own protection is correspondingly low.

What sunscreen should I use?

A basic distinction is made chemical and physical light protection filters. In conventional sunscreen creams, there is often a combination of both variants. The mode of action of the UV filter is different: chemical filters penetrate the skin, render the rays ineffective and thus prevent skin damage. It takes approximately 20 minutes for them to take effect. Physical light protection filters, on the other hand, lie on the skin like a protective shield and reflect sunlight like millions of small mirrors. Such sunscreens protect the skin immediately after use. A generous application is important for both sun creams.

ÖKO-TEST advises against products with chemical light protection filters, since it is known from animal experiments that a number of chemical UV filters have hormonal effects. However, the mineral light protection filters titanium dioxide and zinc oxide are also discussed. Extremely small particles that are smaller than 100 nanometers are often used. The miniatures have the advantage that they are easy to distribute. But the question is whether the mini-minerals can get into the body through the skin.

The Federal Institute for Risk Assessment describes UV filters in nano size as harmful to health, and ÖKO-TEST does not evaluate them in sunscreens because it is important to protect yourself from the sun. And according to current knowledge, mineral filters are less harmful than chemical ones. Studies conclude that the tiny particles cannot penetrate healthy skin. Nevertheless, the BfR sees further research needs for the effects of nanoparticles on humans. The mineral filters titanium dioxide and zinc oxide in nano size are not recommended in sprays. There are signs of a carcinogenic effect if you inhale the nano-sized filter. The use of nanomaterial must be stated in the declaration. Now read the ÖKO-TEST test results for various sunscreens:

What is different about sun protection products from natural cosmetics manufacturers?

Chemical light protection filters are not approved for certified natural cosmetics. As a result, natural cosmetics manufacturers come into sun protection products only mineral filters for use. The companies do not use nanoparticles, although they are not banned per se in natural cosmetics. The products of natural cosmetics manufacturers mostly contain titanium dioxide, which with its size of 400 to 600 nanometers does not fall under the nanoregulation.

What does the UV-A label say on sunscreens?

The sign with the three letters in the middle means that the cream offers a minimum level of UV-A protection in addition to protection against UV-B radiation. The latter can be recognized from the specification of the sun protection factor. The UV-A mark is based on a recommendation by the EU Commission, the statements of which the manufacturer was too inconsistent. The idea: Customers should be able to quickly identify whether the product of their choice offers sufficient UV-A protection in addition to UV-B.

How high should the sun protection factor be?

A sunscreen with an average sun protection factor (SPF) between 15 and 25 is usually sufficient because the additional sun protection does not grow proportionally to the sun protection factor. If an active ingredient with sun protection factor 20 absorbs at least 95 percent of UV-B radiation, there is only a little more with sun protection factor 50, namely 98 percent. A very high sun protection factor, for example for people with pigment disorders or fresh, larger scars. Basically, sunscreens only work if you use them generously, which experience has not shown. You also need to apply cream regularly, as sweat, water, and abrasion reduce the effectiveness of the sunscreen. However, this does not extend the protection period. Read on here: Apply sunscreen correctly.

Sunglasses are a fashion accessory in summer - but do they also protect from the sun?

Sunglasses are a fashion accessory in summer – but do they also protect from the sun? (Photo: CC0 / Andrea Piacquadio / Pexels)

Does sunglasses make sense?

Sunglasses are much more than a chic accessory. Because if the eyes get too much UV radiation, they redden, tear and can hurt. It is known, for example, that UV-B rays promote the development of cataracts and that too much UV-A radiation causes the retina to age and can lead to premature macular degeneration. Allowed in Germany Only sunglasses with UV protection sold. You can tell that the glasses comply with the European standard for UV protection CE marking on the inside of the temple. The guideline guarantees that UV radiation up to a wavelength of 380 nanometers is filtered out. However, many experts recommend sunglasses with higher protection, recognizable by the unfortunately not standardized Inscription UV 400.

How well does a parasol protect?

Even under an umbrella with a sun protection factor of 80, you can contract sunburn without further protection, since the light also falls in from the side and the floor reflects up to 50 percent of the UV radiation. However, not all parasols or beach shells effectively block the dangerous radiation. Not even when a high protection factor is announced, since a uniform standard for the UV protection of textiles has not yet been implemented. In addition, the sun protection effect of the fabric decreases due to stress.

What does UV protective clothing bring?

More and more items of clothing are provided with UV protection information. However, the consumer should pay attention to which standard has been tested. Dr. Andreas Schmidt from the Textile Research Center of the Hohenstein Institute: “Only measurement according to UV standard 801 offers reliable values.” This is the only way to evaluate textiles in a practical way: the fabric is washed before the test, moistened and stretched during the test. A maximum radiation intensity is used when determining the protection factor. The Australian-New Zealand standard (AS / NZS 4399: 1996) and the European standard (EN 13758-1) are measured against new textiles. The Federal Office for Radiation Protection (BfS) comes to the same assessment.

What if the sunburn still burns?

Very important: get out of the sun until the sunburn has completely healed. If you get severe sunburn, you should see a doctor. Drinking plenty of water helps with mild sunburn. In addition, cold envelopes and other home remedies cool down. Also read: What helps against sunburn?

What does a sun allergy look like?

About the causes of the polymorphic light outbreak – commonly referred to as sun allergy – is very little known. It shows by reddening of the skin a few hours after exposure to light, preferably on the décolleté, the arms, the back of the hand, the thighs, the face and the neck. Very itchy pustules, wheals or blisters form. It mainly affects blonde or red-haired women and often children. The sun allergy can get lighter with age or even cure. Preventing calcium tablets helps some. In most cases, the only way to avoid an outbreak is to provide full protection to those affected when the skin is exposed to the sun.

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