Never go out of the house without appropriate sun protection! Avoid the midday sun! Sunscreen alone is not enough, protect your skin with appropriate clothing! Stay in the shade at all costs!
There are many tips for proper sun exposure, some of which are limiting. What could be so bad about lying in the sun for a few hours? The worst case scenario is that you get a little sunburn. And even if it is unpleasant, it usually goes away in a few days.
The consequences of sun exposure
But the warnings are definitely appropriate: There are several diseases that develop only because there is not enough sun protection. Most feared is skin cancer, but even preliminary stages of it are troublesome and also dangerous. Thus, the lack of protection against sun radiation frequently leads to actinic keratosis, a cornification disorder caused by light damage.
Actinic keratosis as skin cancer precursor
Actinic or solar keratosis itself is relatively harmless. Nevertheless, the skin disease is not harmless as it is a preliminary stage of the so-called prickle cell skin cancer which is called spinalioma in medicine. Especially with increasing age it becomes more and more likely that a cancer develops from the harmless actinic keratosis.
Distribution of actinic keratosis
Actinic keratosis occurs mainly in fair-skinned people with blond or red hair, because they have few pigments in their skin that would protect them from the sun's rays.
However, it takes years or even decades for the skin to be damaged enough for the keratinization disorder to develop. This is why actinic keratosis usually only occurs after the age of 50.
Men in particular are frequently affected by the disease, as they often work outdoors. During this time, the skin is rarely sufficiently protected.