Risk of sunburn - What is the UV Index?

When looking at the weather app each day, a figure is frequently overlooked, especially in summer: the UV Index. However, this value is increasingly important, particularly when the temperatures rise. It shows how high the daily UV exposure will be and thus plays an important role in avoiding sunburn.

Significance of the UV Index

[Translate to en_DE:] Holzthermometer mit Gradanzeige

The World Health Organization (WHO) has globally standardised the UV Index (UVI). It describes the expected daily peak value of UV radiation. The higher the value, the higher the risk of sunburn for unprotected skin. The UVI value is open-ended and linked to the recommendations for protection against UV rays. The UVI scale is divided into five levels. The levels reflect the sun protection recommendations for the skin. A UV Index of "7" for example corresponds to a "high risk" and makes "protection necessary".1 The scale is uniformly defined across the globe.

Where can I find the UV Index?

The UV Index can usually be found in the current online weather forecast and in many weather apps. The Federal Office for Radiation Protection (BfS) also has a newsletter available for subscription, informing you about the expected UV Index.2 As is the case with other weather forecasts, the intensity of UV rays cannot be predicted with pinpoint accuracy. However, the UVI certainly provides a good guide for UV exposure. The UV Index always states a maximum daily value, not an average. If the app gives two values, the lower one refers to the radiation under cloudy conditions and the higher one is radiation with a cloudless sky. In Germany, we normally reach levels of up to 5 in spring, up to 3 in autumn and up to 8 in summer.

In winter the value in Germany is between 0 and 2.

Sun protection based on the UV Index

The BfS categorises the UV Index as follows. From a UV Index of three, sun cream and further protective measures are necessary:

[Translate to en_DE:] Glatzköpfiger Mann sitzt am Wasser

Those aware of the UV Index and who find out the information beforehand can take the corresponding protective measures. Sun cream should therefore be applied in the morning and reapplied repeatedly throughout the day. A sun hat and sunglasses are also a must to protect against sunburn. The UVI forecast helps to protect the skin from sunburn and ageing caused by sun exposure during the day. This means that long-term health effects such as skin cancer can also be prevented.

Dr René Stranzenbach, dermatologist and skin cancer specialist, says: "Light exposure occurs increasingly in areas that act as 'light terraces', i.e. on exposed areas such as cheeks, nose, ears or even the scalp."

The sensitive scalp is thus particularly at risk of sunburn. The reason: UV rays fall directly and vertically on the head. Usually, the hair provides natural sun protection. Yet people with balding or thinning hair are missing this protective function. Also people with partings frequently forget that they offer the sun an area of attack that is not covered by hair. The problem of "sunburned scalps" can thus affect both men and women.

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