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InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-.
We all know that too much sun is bad for your skin. But how do you know how long you can stay in the sun? You can't see or feel UV light, so it's difficult to know how strong it is and what effect it will have. Summer heat isn't a good indicator here because UV radiation might also be present when it's cold outside. This is because heat from the sun doesn't come from UV light, but from infrared light in the sun’s rays.
The higher in the sky the sun is, the stronger the UVB radiation on Earth. This is both true in terms of the sun’s position over the course of the day – it's highest at midday – and in terms of geographical location. So UV radiation is particularly high close to the equator, for instance in Florida, Thailand or Central America. It is also high in Australia and New Zealand because these countries are near the hole in the ozone layer above the Antarctic. The thinner the ozone layer, the stronger the UV radiation levels.
UVB exposure tends to be more of a problem in mountainous regions than in lower regions. Snow, water and light-colored sand reflect UV light too, increasing your exposure.
What is the UV Index?
The UV Index (UVI) is a measure of the current intensity of UVB radiation in a certain location. The higher the current UV Index reading, the higher the radiation levels, and the more likely you are to get a sunburn. You can find current UV Index forecasts for Germany on the website of the German Federal Office for Radiation Protection.
| UV Index (UVI) | UV intensity |
|---|---|
| 0 to 2 | Low |
| 3 to 5 | Moderate |
| 6 to 7 | High |
| 8 to 10 | Very high |
| 11 | Extremely high |
The higher the UV Index, the more protection you will need. UV radiation is particularly high in mountainous regions, at the equator and in regions where the ozone layer is thin, such as in Australia. In most places, UVB radiation is at its strongest between 11 a.m. and 3 p.m. because the sun is high in the sky then. UVB exposure is also more of a problem in the summer than in the winter. Thick clouds can reduce UV radiation, but thin clouds don't provide much protection.
How much UV radiation can your skin handle?
Intensive and frequent sunbathing can be too much for your skin to handle. Only if you gradually increase UV exposure over a period of two to three weeks, and only expose your skin to moderate UV radiation, can you achieve a lasting tan that makes the corneal layer of your skin thicker, providing a little protection from the sun. Although this natural UV protection can prevent sunburn to some extent, it can't protect you from all of the different types of damage caused by UV light, and can't prevent skin cancer.
The skin of people who are sensitive to light can't protect itself from UV radiation for long. In very fair-skinned people, UV radiation starts becoming harmful after about 5 to 10 minutes. The table below shows the maximum amount of time people with different types of skin can expose untanned and unprotected skin to the sun per day without getting a sunburn.
| Skin type | Maximum amount of time |
|---|---|
| I | 10 minutes |
| II | 20 minutes |
| III | 30 minutes |
| IV | 50 minutes |
| V | more than 60 minutes |
| VI | more than 60 minutes |
The following can help you determine what type of skin you have:
| Skin type I: |
|
|---|---|
| Skin type II: |
|
| Skin type III: |
|
| Skin type IV: |
|
| Skin type V: |
|
| Skin type VI: |
|
Very light skin and light skin (types I and II) are typical in places like Scandinavia and Great Britain, and people who have a medium brown skin tone with dark eyes and dark hair (type IV) mainly live in the Mediterranean and geographically similar areas. People with even darker or black skin (types V and VI) have their roots in places like certain areas of Asia or Africa.
Sources
- Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften (AWMF), Deutsche Krebsgesellschaft (DKG), Deutsche Krebshilfe (DKH). S3-Leitlinie Prävention von Hautkrebs. AWMF-Registernr.: 032-052OL. April 2014. (Leitlinienprogramm Onkologie).
- Höger P. Kinderdermatologie: Differenzialdiagnostik und Therapie bei Kindern und Jugendlichen. Stuttgart: Schattauer; 2011.
- Lautenschlager S, Wulf HC, Pittelkow MR. Photoprotection. Lancet 2007; 370(9586): 528-537. [PubMed: 17693182]
- World Health Organization (WHO). Global solar UV index. A Practical Guide. 08.2002.
IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.
Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. We do not offer individual consultations.
Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.
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- How much sun is too much? - InformedHealth.orgHow much sun is too much? - InformedHealth.org
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