The UV dose per treatment is determined by two factors: the duration of exposure and the intensity of the radiation reaching the skin.
In practice, it is usually only the duration of exposure that is adjusted. It is extended or shortened as required. The intensity of the radiation should always remain the same.
The irradiation intensity depends on the UV lamp as well as the distance between the lamp and the skin. To maintain a consistent intensity, the distance between the UV device and the skin must therefore remain the same. A UV comb is therefore always placed with its teeth resting directly on the skin.
The duration of a treatment depends on your individual sensitivity to UV light. Depending on your skin type, you start with a short exposure time. This is gradually increased from treatment to treatment until the so-called erythema threshold is reached. The erythema threshold manifests as a mild sunburn: the skin becomes slightly red, but the redness subsides quickly. The instructions for use contain tables for each skin type, showing suitable starting times and increments.
As the treatment progresses, the duration of each session is also based on the erythema threshold. The skin reacts with increased pigmentation (tanning) and the formation of a photodermatosis. These changes lead to an increase in the erythema threshold. As a result, the skin can tolerate more UV radiation. The exposure time – and thus the UV dose – can be further increased as the treatment progresses.
