How do I find the right sun protection factor?
The level of the recommended sun protection factor depends on the individual skin type. To define this, you can orientate yourself on a special scale. According to the skin type it is indicated how long one could theoretically stay in the sun without sunburn.
However, this strongly depends on the environment. In the tropics, in the high mountains or on the water, this value is significantly lower because the sun's rays are much more intense because they are reflected. The self-protection time, multiplied by the SPF (Sun Protection Factor), results in the maximum protection time for each individual person per day. To be on the safe side, another 20% should be deducted from this.
What is self-protection time?
Self-protection time of the skin describes the amount of time that a person can spend unprotected in the sun within a day before the skin begins to redden. It depends on the skin type, the amount of sunlight and the environment. If you are in the water, for example, the self-protection time of the skin decreases due to the reflection of the sun's rays in the water.
To be on the safe side, it is therefore generally recommended to only use around 60% of the self-protection time. However, if you then consider the self-protection times given above and subtract a third from this, there is not much time left for sunbathing for most skin types.