Impact of Orientation on the Vitamin D Weighted Exposure of a Human in an Urban Environment

Michael Schrempf, Nadine Thuns, Kezia Lange and Gunther Seckmeyer
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Michael Schrempf: Institute of Meteorology and Climatology, Leibniz Universität Hannover, 30419 Hannover, Germany
Nadine Thuns: Institute of Meteorology and Climatology, Leibniz Universität Hannover, 30419 Hannover, Germany
Kezia Lange: Institute of Meteorology and Climatology, Leibniz Universität Hannover, 30419 Hannover, Germany
Gunther Seckmeyer: Institute of Meteorology and Climatology, Leibniz Universität Hannover, 30419 Hannover, Germany

IJERPH, 2017, vol. 14, issue 8, 1-11

Abstract: The vitamin D 3 -weighted UV exposure of a human with vertical posture was calculated for urban locations to investigate the impact of orientation and obstructions on the exposure. Human exposure was calculated by using the 3D geometry of a human and integrating the radiance, i.e., the radiant energy from the direct solar beam and the diffuse sky radiation from different incident and azimuth angles. Obstructions of the sky are derived from hemispherical images, which are recorded by a digital camera with a fisheye lens. Due to the low reflectivity of most surfaces in the UV range, the radiance from obstructed sky regions was neglected. For spring equinox (21 March), the exposure of a human model with winter clothing in an environment where obstructions cover 40% of the sky varies by up to 25%, depending on the orientation of the human model to the sun. The calculation of the accumulated vitamin D 3 -weighted exposure of a human with winter clothing walking during lunch break shows that human exposure is reduced by the obstruction of buildings and vegetation by 40%.

Keywords: UV radiation; human exposure; vitamin D; urban environment; hemispherical sky images; radiance (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2017
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