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Health consequences of UV radiation

Sunny spring days entice us outdoors, but even in mild temperatures, UV radiation should not be underestimated.

Why sun cream and co are important now.

 People usually only think about sun protection when it gets really hot. But UV radiation is invisible and does not depend on the air temperature.

Even on cool days, there is a risk of damage to health.

The sun emits high-energy ultraviolet rays of various wavelengths: The UV-C component is completely absorbed by the ozone layer. In contrast, up to ten percent of UV-B radiation reaches the earth’s surface, while the UV-A component passes through the atmosphere almost unhindered.

Direct consequences

– Reddening of the skin up to sunburn, swelling, blistering, itching, pain

– Sun allergy with wheals and blisters

– Inflammation of the cornea or conjunctiva of the eye (e.g. snow blindness)

– Suppression of the immune system

– Formation of vitamin D (the only known positive biological effect of UV radiation)

Late effects

– Eye damage such as cataracts or uveal melanoma (eye tumor)

– Accelerated skin ageing

– skin cancer

The intensity of UV radiation depends on the time of year, time of day and latitude.

It is more intense in the summer months than in winter, and is most dangerous during the day at midday.

In addition, the radiation intensity increases the closer you get to the equator.

Without sun protection, the UV rays penetrate the skin and eyes and can cause damage.

The main cause of reddening of the skin is UV-B radiation, which mainly penetrates the epidermis, whereas UV-A radiation reaches the deeper layers of the skin.

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UV index as a guide

The daily UV exposure and therefore the health risk at a location can be estimated using the UV index (UVI). It is published regularly by the German Weather Service and the Federal Office for Radiation Protection. The higher the index, the faster sunburn can occur on unprotected skin

 The scale was developed by the World Health Organization and is internationally standardized. A UVI of 5, for example, means the same in USA as in South Africa.

More and more spring sunshine

In spring, the sun gains strength from day to day, even if the heat is still moderate. Measurement data shows that UV index values that make sun protection necessary can be reached as early as March.

The German Weather Service is also registering more and more hours of sunshine in spring. On average, the sun now shines 87 hours longer across Germany than in the period from 1961 to 1990, which further increases the UV risk.

According to the President of the Federal Office for Radiation Protection, Inge Paulini, not everyone knows that you have to be careful even on sunny spring days. But “the awareness of many people that UV protection is important is growing”.

Water, sand and snow reduce radiation by reflecting it.

Shade, on the other hand, reduces UV exposure: under a parasol, for example, by around 10 to 30 percent, under a large tree with a dense canopy by around 20 percent.

The lighter the skin, the less it can protect itself against sunlight and the more sensitive it reacts. Skin that contains a lot of melanin and is therefore darker is better protected, but skin damage cannot be ruled out here either.

Children and adolescents need special protection as they are much more sensitive to UV rays than adults. Experts recommend that infants and small children under the age of two should not be exposed to the sun at all with uncovered skin.

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How does tan develop (from Wikipedia)

There are two different mechanisms involved in production of a tan by UV exposure.

Firstly, UVA radiation creates oxidative stress, which in turn oxidizes existing melanin and leads to rapid darkening of the melanin. UVA may also cause melanin to be redistributed (released from melanocytes where it is already stored), but its total quantity is unchanged. Skin darkening from UVA exposure does not lead to significantly increased production of melanin or protection against sunburn.

In the second process, triggered primarily by UVB, there is an increase in production of melanin (melanogenesis), which is the body’s reaction to direct DNA photodamage from UV radiation. Melanogenesis leads to delayed tanning, and typically becomes visible two or three days after exposure.

The tan that is created by increased melanogenesis typically lasts for a few weeks or months, much longer than the tan that is caused by oxidation of existing melanin, and is also actually protective against UV skin damage and sunburn, rather than simply cosmetic. Typically, it can provide a modest Sun Protection Factor (SPF) of 3, meaning that tanned skin would tolerate up to 3 times the UV exposure as pale skin. However, in order to cause true melanogenesis-tanning by means of UV exposure, some direct DNA photodamage must first be produced, and this requires UVB exposure (as present in natural sunlight, or sunlamps that produce UVB).

Source: https://en.wikipedia.org/wiki/Sun_tanning#Tanning_process