Diffuse solar ultraviolet radiation and implications for preventing human eye damage

Abstract

[Abstract]: Ocular UV exposure is a function of both the direct and diffuse components of solar radiation. Broadband global and diffuse UV measurements were made in the morning, noon and afternoon. Thirty sets of measurements were made in summer and fifty in each of the other seasons at each of the periods in full sun. Corresponding sets were made in the shade of Australian evergreen trees: 42 trees in summer and 50 in each of the other seasons. The percentage diffuse UV was higher for the shorter UVB than for UVA. The percentage diffuse UVB ranged from 23% to 59%, whereas the percentage diffuse UVA ranged from 17% to 31%. The percentage diffuse UV was lower at noon than in the morning and afternoon with the difference more pronounced for the UVB. The average percentage diffuse UVB over all the measurements in the tree shade for the morning, noon and afternoon was 62%, 58% and 71% respectively and the average percentage diffuse UVA was 52%, 51% and 59% respectively.