The use of commercially available personal UV-meters does cause less safe tanning habits: a randomized-controlled trial.
UV Index information is currently recommended as a vehicle to raise public awareness about the risk of sun-exposure. It remains unknown to what extent this information can change personal sun-protective behavior. The aim of the study was to analyze the effects of UV-Index (UV-I) information provided by low cost, commercially available UV-I sensors on major indicators of sun-tanning behavior. A randomized-controlled trial was carried out on 94 healthy volunteers aged 21-23 years. After the exclusion of subjects with photosensitive disorders (n=3), 91 subjects were randomized in two arms after stratification based on phototype and sex. Both arms received a diary to be filled every day with a log of intentional sun-exposure during summer. Subjects in the intervention group also received a commercially available UV-I sensor. The UV-I sensors were switched on and the UV-value was recorded in 77% of days with sun-exposure. During days of sun-exposure, subjects randomized to the intervention group had longer average time of sun-exposure (227.7 vs 208.7 min per day, P=0.003), also between noon and 4 pm (P<0.001), and less frequently adopted sun protective measures than controls (hat [6.4%vs 10.2%, P=0.007], sunglasses [23.9%vs 30.8%, P=0.003], sunscreen [41.4%vs 47.2%, P=0.02]) and they experienced more frequent sunburns (27.8%vs 21.5%, P=0.004). The odd ratio of sunburns was 1.60 for subjects in the intervention group compared with controls (after adjustment for sex, sunscreen use and skin type). The mean UV-I value recorded by volunteers was lower (5.6 [SD+/-0.9]) than that (7.3 [SD+/-0.46]) recorded by a professional instrument in the same period at the same latitude. Poststudy laboratory tests showed that the sensor was able to detect only about 60% of the solar diffuse radiation. The use of UV-I sensors changed the sun protective behavior of sunbathers in the direction of less use of sun protective measures. One possible explanation is that the low cost UV-meters may have functioned incorrectly and under-reported UV exposure. This may have led to an underestimation of UV-I values, erroneously reassuring subjects and causing a less protective sunbathing behavior. Another hypothesis relies on a cognitive pitfall in the subjects' dealing with intermediate UV-I values, as they may have been discouraged in the use of sunscreen as they did not feel that they had yet been exposed to very harmful UV radiation.
Carli
Paolo
P
Department of Dermatology, University of Florence, Italy.
Crocetti
Emanuele
E
Chiarugi
Alessandra
A
Salvini
Camilla
C
Nardini
Paolo
P
Zipoli
Gaetano
G
Simeone
Emilio
E
D000328:Adult; D002138:Calibration; D005260:Female; D006370:Heliotherapy / Q000295:instrumentation; D006801:Humans; D008297:Male; D011829:Radiation Dosage; D011874:Radiometry / Q000191:economics / Q000295:instrumentation / Q000592:standards; D012449:Safety; D013471:Sunburn / Q000209:etiology / Q000517:prevention & control*; D013472:Sunlight / Q000009:adverse effects*; D013473:Sunscreening Agents / Q000627:therapeutic use; D014466:Ultraviolet Rays / Q000009:adverse effects*
D013473:Sunscreening Agents