The sun protection factor (SPF; LF; Sun Protection Factor (SPF)) indicates how many times longer one can be exposed to the sun (UVA and UVB rays) with a sunscreen (sunscreen) without getting a sunburn (= perceptible reddening of the skin) than would be possible with the respective individual self-protection time. To calculate the self-protection time of the skin, the following applies: self-protection time (between 5 to 15 minutes, depending on skin type) times the level of the sun protection factor. For example: 10 minutes times sun protection factor 6 results in 60 minutes. This means that one may expose oneself to the sun for 60 minutes.
A sunscreen with a SPF of 30 absorbs 96.7 percent of the sun’s skin-reddening rays, while a sunscreen with a SPF of 60 absorbs about 98.3 percent. This means that increasing the SPF from 30 to 60 results in a halving of the transmitted radiation from 3.3 percent to 1.7 percent (double protection).
According to an Australian study, years of sunscreen use led to a reduction in the risk of melanoma and squamous cell carcinoma of the skin by about 50%, but the risk of basal cell carcinoma was not affected.
Caution. The skin ages mainly due to light (= photoaging). External influences such as UV rays and free radicals are responsible for up to 80% of premature skin aging.Here are some more tips on the sun protection factor:
- The higher the sun protection factor, the greater the protective effect of the product.
- The effectiveness of the protection depends on the amount of product used and how evenly the product is applied.
- It is recommended to apply the sunscreen product at least half an hour before sun exposure, so that the protective filter can be well distributed in the skin.
- From the 40th to 50th year of life, the number of melanin-producing cells decreases continuously. At this age, every skin type therefore needs considerable protection in the first days of sun, so that the more sensitive skin can achieve a well-groomed tan.
- The tan is a natural adaptation and protective response to the sun. It forms only after 42 hours and reaches its peak after a few days of regular sun exposure. Therefore, protect your skin from the sun especially intensively during the first days of sun exposure. This is the only way to prevent skin irritation, because only on a well-groomed skin can develop a radiant and long-lasting tan.
- Do not use perfume, eau de toilette or deodorant in the sun. This can cause brown spots on the skin, which are very difficult to disappear.
Attention. For prolonged exposure to the sun or water, the application of the product should be repeated regularly. Note: Only clothing provides reliable protection against UV-induced mutations (permanent changes in genetic material). This protection can be supplemented or improved by applying sunscreen. See also more information on “Skin type and SPF” under the topic of the same name.