[Sun exposure at school: Evaluation of risk (erythema dose), benefits (vitamin-D synthesis) and behaviour among children in France]

Abstract

Background: To better understand the potential risk associated with sun exposure during the school year, we decided to evaluate behaviour, risk [UV index (UVI), minimal erythema dose (MED)] and benefits (vitamin-D synthesis) of sun exposure in primary schoolchildren in France, as well as the various sun protection methods used for children.

Material and methods: We performed the study on a sunny day (July 24) in a school in Antony (France). Evaluation of UVI (with calculation of MED) and the amount of vitamin D synthesized according to exposed body surface area and phototype were performed every 15minutes from 9 a.m. to 5 p.m. The effects of albedo and shade on UVI were assessed in 8 different locations at the school. The sun-protection measures used by the children were systematically evaluated.

Results: Fifty-seven children were evaluated; the maximum UVI was 7.2 and the maximum temperature was 30.7°C. Irrespective of phototype and clothing, 1 MED was reached and an adequate level of vitamin D was synthesized in the skin before midday. Albedo had little impact on irradiation. The amount of protection afforded by shadow varied greatly, with the highest level occurring in the covered courtyard (99.5% reduction of UVI) and the lowest in the shadow of buildings (53.7% reduction of UVI). With strict sun protection measures concerning dress, children reached 1 MED before synthesizing 1000IU of vitamin D, but with clothing "suited to high temperatures", 1000IU of vitamin D were synthetized before 1 MED was reached. Compliance with photoprotection measures was poor. Regardless of duration of exposure during the day (minimal model: two play breaks+lunchtime break) and of skin phototype, at least 1.5 MED was reached during the day.

Study limitations: This was an experimental study ignoring children's actual behaviour (movement, sweating, application of sun protection products, etc.). Moreover, due to weather conditions, the study was performed at a recreation centre in July and not during the "standard" school year.

Conclusion: Sun protection campaigns should naturally be directed chiefly towards children for several reasons relating to solar risk and learning. This study shows the complex link between UV, MED, vitamin D as well as the difficulties of implementing solar protection measures in schools in France.

Keywords: Children; Enfants; Facteurs de risque; Indice de confort cutané; Risk factor; Skin discomfort index; Ultraviolet; Ultraviolets; Vitamin D; Vitamine D.