Scattered UV beneath public shade structures during winter

Abstract

[Abstract]: Broadband field measurements were conducted beneath three different sized public shade structures, small, medium and large, during the Southern Hemisphere winter. These measurements were compared to the diffuse UV to quantify the relationship of the UV under and around the shade structures to the diffuse UV. For the shade structures, a relationship between the diffuse UV and the UV in the shade has been provided for clear skies and solar zenith angles (SZAs) of 49o to 76o. This allows the prediction of the UV in the shade of these structures if the diffuse UV is known. The ultraviolet protection factors (UPFs) for the three shade structures ranged from 1.5 to 5.4 for decreasing SZA. For the greater SZAs of 70o to 76o, the erythemal UV in the shade was 65%, 59% and 51% of that in full sun for the small, medium and large structures respectively. For the smaller SZAs of 50o to 53o the erythemal UV in the shade was 35%, 41% and 18% for the small, medium and large shade structures respectively. From this research it can be concluded that the UV radiation levels in the shade in winter could cause erythema and other sun related disorders.