Why does sunburn occur?
Sunlight exposes the earth to UV radiation, the intensity of which depends on the position of the sun, the thickness of the ozone layer, altitude and weather conditions.
Depending on the wavelengths of the UV rays, a distinction can be made between UVA (long-wave) and UVB (short-wave) rays, which can penetrate the skin to different depths.
The skin has its own natural protective system to defend itself against these. The intrinsic protection time, however, is limited and depends on your skin type, any pre-tan and the intensity of the sun (UV index).
In the event of excessive sun exposure, your natural protection is no longer enough and there is a risk of sunburn. The energy of the UV light damages skin cells, causing the skin to become irritated and inflamed, resulting in redness or even blisters.