Light protection

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).

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%.

Profile:

Defin.: Protection of the skin against excessive light absorption. See also UV index. In addition to physiological light protection, the light callus, a distinction must be made between artificial light protection through textiles (clothing) or through (chemical or physical) light protection agents. Recently, orally administered substances have also been advertised as sunscreens (e.g. Polypodium leukotomis extract [PLE] obtained from a Central American fern plant, e.g. in Heliocare capsules; see also β-carotene below).

Sun protection factor: Quotient of the erythema threshold dose of the protected skin(MED) and the erythema threshold dose of the unprotected skin. For example, a sun protection factor (SPF) of 6 means a six-fold increase in exposure time before erythema occurs within 24 hours. In Germany, the sun protection factor is indicated on products with the abbreviation SPF or SF + number. The French term IP stands for Indice de Protection and is identical to the German specification. The American factor SPF stands for Sun Protecting Factor and is calculated differently from SPF/SF and IP. For this reason, you have to subtract around 30% from an SPF to obtain a German or French value. An SPF 24 is therefore roughly comparable to an SPF/SF or IP 16.

General information on the use of sunscreens:

• Apply sunscreen products 30 minutes before sun exposure and repeatedly after each bath.
• Use waterproof sunscreens when bathing.
• Reapplying the sunscreen does not extend the specified total protection time!
• Wear lightproof textiles and hats with a wide brim.
• Wear UV-absorbing sunglasses.
• Textiles have a significantly higher UV permeability when wet (UV permeability of a cotton T-shirt is increased by around 50% when damp or wet, e.g. when sweating heavily).
• Daily use of a sun protection product with a sun protection factor of at least 15 on uncovered areas of the body, which is also effective in the UVA range.
• Sun protection products with a sun protection factor (SPF) of 15 have a protection factor of around 93%. Products with an SPF of 30 or 45 filter only slightly more (around 96-97%).
• Sun protection products with a higher SPF are only recommended for very UV-sensitive people (see below light dermatoses) and special risk situations (spending time in high mountains, e.g. skiing).
• UVA radiation contributes significantly to skin ageing(photoageing; see below Elastosis actinica) and possibly also to the development of malignant melanoma and should therefore also be filtered in addition to UVB.
• UV lip protection: Choose a UV-protective lipstick (sun protection factor 30), as the unprotected red of the lips is very sensitive to UV radiation. The natural protective mechanism of tanning is missing here.
• UV exposure of unprotected body regions (as a percentage of the total dose):
  • highest dose on the crown of the head
  • Shoulders (regardless of the type of physical activity) 75% of the total dose.
  • Hands: approx. 30-50%
  • Back: 40-60%
  • Chest: 25-70%
  • Thighs: 25-33%
  • Calves: approx. 25%.
• UV exposure of the face (as a percentage of the value on the top of the head):
  • Forehead and nose: approx. 20-65%
  • Cheeks: 15-40%
  • Chin: 20-35%
  • Neck: 20-35%.

Further general advice: Most important rule = avoid intensive, direct and indirect UV exposure from natural (sun) and artificial UV sources (solariums). This is followed by "clothing", textile light protection, in particular the wearing of UV-proof headgear and UV-proof textiles (see below). In addition, use sunscreenswith a sun protection factor (SPF ) of at least 15 with a broad protective effect in the UVB and UVA range.

• The following sun protection rules can be briefly summarized:
  • (4-H rule): Shirt-trousers-hat-high sun protection or
  • Avoid-dress-cream".
• General rules and advice for UV radiation exposure of the skin:
  • Avoid the sun when the skin is still pale (accustomed to the sun) and has no pre-tanning.
  • Slowly adapt the skin to UV radiation by acquiring a natural light callus!
  • 50% of UV exposure occurs in the midday hours between 11 am and 2 pm.
  • Shade reduces UV radiation by around 50%.
  • UVB rays (and infrared rays) are at their most intense when the sun is at its highest. This warns you of too much UV radiation by heating the skin. This warning does not apply in windy and cold weather!
  • 90% of UV rays penetrate through the cloud cover.
  • UVA light penetrates window glass (attention drivers; important for patients with light dermatoses induced predominantly by UVA rays).
  • The higher the altitude, the higher the UV radiation. The rule of thumb is an increase of 15% per 1000 m.
  • UV radiation changes with increasing altitude. At high altitudes, medium-wave UV increasingly 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 meter.
  • Avoid cosmetics and fragrances (deodorant, perfume, hairspray) before sun exposure. Risk of permanent brown pigmentation, especially on the face and neck (triggered by essential oils such as lavender, lime, sandalwood, cedar and lemon oil, musk). See also dermatitis, berloque dermatitis and dermatitis, phototoxic.
  • Medications can lead to severe phototoxic reactions or dermatitis solaris (antibiotics, high blood pressure medication, tranquilizers, diabetes medication, lipid-lowering medication, rheumatism medication, 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 reached before the age of 18. Severe sunburns in childhood and adolescence before the age of 15 increase the later risk of developing malignant melanoma by a factor of 3-5.
  • Parents' responsibility: Children have no negative experience of their own with the sun and therefore no awareness of possible consequential damage.
  • Children, especially infants, should not play in the sun without clothing.
  • Babies should never be exposed to direct UV radiation.
  • Sunproof T-shirts or shirts, long pants and suitable shoes (not sandals) protect the body from the sun's rays.
  • Choose wide-brimmed hats as headgear.
  • Ultraviolet Protection Factor (UPF) for sunproof clothing: UPF classifies a sun protection factor that indicates the filtering effect of clothing. In Europe, only textiles that have a UPF of at least 30 and in which the proportion of UVA radiation that passes through is less than 5% are labeled. This clothing is recommended for children on sun vacations.
  • Children are best kept in the shade, especially at lunchtime.
  • Protect the eyes with sunglasses with a UV filter.