Minimal erythema dose
The minimum erythema dose (MED) (also known as erythema threshold dose ) is a measure of the tolerance of the human skin to solar radiation , in particular to the short-wave ultraviolet portion of the spectrum around 300 nm wavelength. Dermatologists determine the MED by irradiating a test field (usually on the buttocks) with gradually increased doses (so-called "light stairs") from a strong UV lamp. MED was first proposed in 1921. The subjectivity of the reading and the different radiation sources used cause great uncertainty in the measured and published values; a more standardized size weighted according to the spectrum was therefore proposed ( standard erythema dose SED ).
1 MED corresponds to the lowest radiation dose which, when read after 24 hours, caused a sharply defined erythema (reddening) of the skin. This dose varies widely even in people with the same skin type . In fair-skinned people with skin type II, 1 MED corresponds to around 250–400 J / m² (25–40 mJ / cm²).
To prevent sunburn , the self-protection time is also used, which specifies the maximum time spent in summer midday sun until the erythema occurs. It is 20 minutes for pale winter skin type II, but it can be increased tenfold by tanning the skin.
| Skin type | MED in J / m² | Self-protection time in min at UV index 8 (0.2 W / m²) |
|---|---|---|
| I. | 150-300 | 10 |
| II | 250-400 | 20th |
| III | 300-500 | 30th |
| IV | 450-600 | 50 |
| V | 600-900 | > 60 |
| VI | 900-1500 | > 60 |
swell
- Peter H. Höger: Pediatric Dermatology: Differential Diagnosis and Therapy in Children and Adolescents; with 272 tables . Schattauer Verlag, 2007, ISBN 978-3-7945-2489-1 , p. 393 (accessed on August 17, 2013).
- PU Giacomoni: Sun Protection in Man . Elsevier, July 31, 2001, ISBN 978-0-08-051816-9 , pp. 51-53 (accessed August 17, 2013).
Individual evidence
- ↑ KW Haußer, W. Vahle: Sunburn and tanning. Wiss Publication Siemens Group 6 (1927): 101–120