Light protection

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 29.10.2020

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Sun protection; UV protection

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Protection of the skin against excessive light absorption. See also UV Index. Besides the physiological light protection, the light callosity, an artificial light protection by textiles (clothing) or by (chemical or physical) light protection agents has to be distinguished. Recently, orally administered substances have also been advertised as sunscreens (e.g. Polypodium leukotomusextract [PLE], which is extracted from a Central American fern plant, e.g. in Heliocare capsules; see also β carotene).

General definition
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Apply sunscreen (sunscreen products) 30 minutes before sun exposure and repeat after each bath.

Use of waterproof sunscreens (sun protection products) during bathing

The indicated total protection time is not extended by "re-creaming" the light protection agent!

Wear lightproof textiles and hats with wide brim.

Wear UV-absorbing sunglasses.

Textiles have a significantly higher UV transmission when wet (UV transmission of a cotton T-shirt is increased by about 50% when wet or damp, e.g. when perspiring heavily).

On uncovered parts of the body daily use of a sun protection preparation with a sun protection factor of at least 15 and an effectiveness also in the UVA range.

Sun protection preparations with a sun protection factor (SPF) of 15 have a protection factor of about 93%. Preparations with a SPF of 30 or 45 filter only slightly more (about 96-97%).

Sun protection products are divided into 4 groups: low protection (SPF 6,10), medium protection (SPF 15,20,25), high protection (SPF 30,50), very high protection (SPF >50).

Only for very UV-sensitive persons (see below light dermatoses) and special risk situations (stay in high mountains e.g. skiing) sun protection preparations with higher LF are recommended.

UVA radiation contributes considerably to skin aging ( light aging; see Elastosis actinica) and possibly also to the development of malignant melanoma and should therefore be filtered in addition to UVB.

UV lip protection: Choice of a UV-protective lipstick (sun protection factor 30), as the unprotected lip red is very sensitive to UV. The natural protective mechanism of tanning is missing here.

UV exposure of unprotected areas of the body (as a percentage of the total dose):

  • Highest dose at the crown of the head
  • Shoulders (regardless of the type of physical activity) 75% of the total dose.
  • Hands: about 30-50%.
  • Back: 40-60%
  • Chest: 25-70%
  • Thigh: 25-33%
  • Calves: about 25%.

UV exposure of the face (as a percentage of the value at the crown):

  • Forehead and nose: approx. 20-65%
  • Cheeks: 15-40%
  • Chin: 20-35
  • Neck: 20-35%.

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Light protection measures affect all fair-skinned people. Excessive light protection must be used in the case of light-induced diseases (see below light dermatoses)

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Most important rule = Avoid intensive, direct and indirect UV exposure from natural (sun) and artificial UV sources (solariums) This is followed by "dressing", i.e. textile sun protection, in this case especially the wearing of UV-tight headgear and UV-tight textiles (see below). Supplementary: Use of sun protection agentswith a sun protection factor (LF) of at least 15 with a broad protective effect in the UVB and UVA range.

In short, the following slogan applies: "MEIDEN - KLEIDEN - CREMEN".

  • General rules and instructions for UV radiation exposure of the skin:
    • Avoid the sun when the skin is still pale (weaned from the sun) and has no pre-tan.
    • Slowly adapt the skin to UV radiation by acquiring a natural light callosity!
    • 50% of UV exposure occurs in the midday hours between 11-14 o'clock.
    • Shadow reduces UV radiation by around 50%.
    • UVB rays (and infrared rays) are most intense at the time of the highest sun position. This warns you against too much UV radiation by warming your skin. This warning message does not apply to wind and cold!
    • 90% of UV rays penetrate through the cloud cover.
    • UVA light penetrates window glass (Attention motorists; important for patients with light dermatoses mainly induced by UVA rays).
    • With increasing altitude the UV radiation increases. As a rule of thumb, an increase of 15% per 1000 m is considered.
    • UV radiation changes with increasing altitude. At higher altitudes, medium wave UV radiation reaches the earth's surface (Attention: skiers and mountaineers)
    • Snow reflects 80-90% of UV rays.
    • Sand reflects up to 50% of UV rays.
    • Water reflects 40-50% of UV rays.
    • 50% of UVB and 75% of UVA rays reach a water depth of 1 m.
    • Avoid cosmetics and perfumes (deodorant, perfume, hairspray) before exposure to the sun. Danger of permanent brown pigmentation spots, especially on the face and neck (caused by essential oils such as lavender, lime, sandalwood, cedar and lemon oil, musk). S.a.u. Dermatitis, Berloque dermatitis and dermatitis, phototoxic.
    • Medicines can cause severe phototoxic reactions or dermatitis solaris (antibiotics, hypertension drugs, sedatives, diabetes drugs, fat reducers, rheumatism drugs, hormones for contraception and others).
    • Self-tanning products are a safe alternative to UV tanning.
    • When using solariums, they should bear the "Certified Solarium" seal of approval.
  • Sun protection for children:
    • Up to 25% of individual sunlight exposure is achieved before the age of 18. Severe sunburn in childhood and adolescence before the age of 15 increases the later risk of developing malignant melanoma by a factor of 3-5.
    • Parental responsibility: Children have no negative experiences with the sun and therefore no awareness of possible consequential damage
    • Children, especially toddlers, should not play in the sun without clothing.
    • Infants should not be exposed to direct UV radiation.
    • Sunproof T-shirts or shirts as well as long trousers and suitable shoes (no sandals) protect the body from the radiation.
    • Choose broad-brimmed hats as headgear.
    • Ultraviolet Protection Factor (UPF) for sunproof clothing: UPF classifies a sun protection factor that indicates the filtering effect of the clothing. In Europe, only textiles with a UPF of at least 30 and with a UVA radiation penetration rate of less than 5% are awarded the UPF. This clothing is recommended for children on sunny holidays.
    • It is best for children to stay in the shade, especially at lunchtime.
    • Protect your eyes with sunglasses with UV filters.


Last updated on: 29.10.2020