Swedish pre-school children's UVR exposure - a comparison between two outdoor environments

Background: Overexposure to ultraviolet radiation (UVR) in childhood is a major risk factor for skin cancer. Shady environments are recommended as one method of protection. Methods: Environmental exposure to UVR and environmental protection were assessed by dosimeter measurements on 64 children aged 1-6 years at two geographically close and topographically similar pre-schools outside Stockholm. Outdoor play constructions of site 1 (34 children) were mainly exposed to the sun, and those of site 2 (30 children) were mainly shaded. Dosimetry was carried out during 11 work days in May-June 2002 under clear weather conditions. The reliability of dosimeters was tested with meteorologically modelled data from SMHI, and with stationary dosimeters exposed to free sky, and compared with other UV instruments. The differences between children's outdoor stays were adjusted for. Results: The children's average daily exposures were approximately 200 J(CIE)/m(2) erythemally effective UVR. The average relative UVR exposure (% total available UVR 08:30-18:30) was 6.4% (7.0% at site 1, 5.7% at site 2). Fractions of available UVR during outdoor stay were 14.4% (both sites), 15.3% (site 1), and 13.3% (site 2). In terms of relative differences, 5-6-year-old children at site 2 were exposed to 41% less UVR, and 1-4-year-old children 6% less than those at site 1. Conclusion: The difference can be explained by the children's outdoor pre-school environments, and the behaviors linked to these environments. It is recommended to consider the attractiveness of shady environments in the design of children's pre-school playgrounds, particularly if these are extremely exposed to the sun.