Chatting with friends in a street café or a beer garden on sunny days are
life’s little pleasures. Indeed, the brightness and warmth of the sun positively influence our emotion and well-being.
In these moments almost nobody would have considered using sunscreens or would have thought in such a short time they would not get a sunburn. There is still a strong belief that absence of visible damage means no damage at all in the skin.

Unfortunately this is wrong. UV rays are quietly causing DNA mutations, oxidative stress and immunosuppression from the moment we expose ourselves to sun light.
The lowest UV light dosage necessary to cause sunburn is called 1 Minimal Erythemal Dosage (MED). As long as the radiation intensity stays below sunburn it is called “sub-erythemal” dosage.
Evaluation of human skin biopsies after UV exposure is a helpful tool to identify sub-erythemal UV damages. By this experimental set-up we have shown that already at 0.6 MED ...