Interview with a dermatologist Sun protection myths in check

Don't apply sunscreen in the shade? Dispose of sunscreen at the end of summer? There are still many misconceptions about sun protection. "Bluewin" spoke to an expert.

Reinhard Dummer, you are Director of the Dermatology Clinic at the University Hospital Zurich. Misconception or truth:

Misconception, because a sun protection factor of 30 only protects 30 times longer in theory. Experience shows that in everyday life it is about a third of the sun protection time. With a sun protection factor of 30, we expect a maximum of 10.

However, this only applies to those who apply sunscreen very carefully. Protection is significantly reduced by movement, friction - for example from clothing - sweating, water, dripping or drying off after swimming. If you reapply sun cream, you can maintain the maximum sun protection time, but not extend it.

The shade is a good sunscreen. It reduces the radiation by about half. However, there are big differences in sun blinds, for example. Some only absorb around ten percent of UV radiation, while really good blinds absorb more than 50 percent. However, especially on the beach or by the water, there is not only direct radiation from above, but also reflected radiation from the side.

The sun protection factor of clothing depends on the fabric and color. The lighter and thinner the clothing, the less well it protects. You can test the clothes with the so-called window test: If you hold the fabric up to the light and can still make out the outline, the sun protection factor is low. This is even worse if the clothing gets wet, during sport, in water or when sweating. Anyone who is active outdoors should wear UV-tested clothing.

If you have very fair skin or red hair, you can't really prepare for the sun at all. A medium skin type with dark eyes and hair cannot produce more than SPF 5 through their own tanning. A darker skin type can count on a higher sun protection factor, but is not protected from sunburn.

The sun protection factor of the skin is not only created by the pigments, the dark pigment melanin, but also by the so-called light callus, a thickening of the cornea as a reaction to UV radiation. Most Swiss people have skin types from 1 to 4, so they need high to very high skin protection from SPF 30 to 50+.

I can only warn against low sun protection, as this is as good as no protection at all. Anything below SPF 30 makes no sense. You can also get a summer complexion if you apply a high level of protection.

You can store it well. Many creams also have an expiry date on the tube. As a rule, you can count on a good formulation; most sun creams also contain preservatives. It is only important that they are not exposed to excessively hot temperatures. So it's better not to leave them in the car or in the blazing sun.

When the sweat runsSo the sun cream doesn't sting your eyes

As with everything in life, it depends on the dose. A single sunburn can repair our skin, so there's no need to panic. Rather, it is the total UV exposure that can cause skin cancer. This also includes exposure below the sunburn dose, which can also change the genetic material in the cells. It is better to stay out of the sun and expose your skin artificially.

I protect myself with protection factor 50+. I like to take a siesta with my family on vacation. I take care of my clothes, wear thicker fabric and do the light test if I'm going to be outdoors a lot.

When I'm in the mountains or doing sport, I also protect myself with specific sun protection clothing. I always wear large sunglasses and have several straw hats - for me, this is one of the simplest but most effective tips.

Further information on sun protection is also available from the Swiss Cancer League.