[Abstract]: A method for the three dimensional representation of erythemally effective ultraviolet radiation (UVery) incident to the human body has been developed from a series of polysulphone dosimeter (PS) measurements to the face, neck, arms, legs and hands of a manikin model. The technique has been used to represent a series of human UVery exposure patterns in the solar zenith angle (SZA) range 30o-50o measured in an open environment in Toowoomba, Australia (27.5oS 151.9oE). The human body representations of exposure presented here improve upon existing techniques to represent the UVery exposure to complex body shape topography, providing for the first time, estimates of exposure that take whole body shading effects into account from high density PS dosimeter measurements

Downs, Nathan

Parisi, Alfio

English

University of Southern Queensland ePrints

Patterns in Surface Distribution of Human Exposure to Solar Ultraviolet N.J. Downs and A.V. Parisi University of Southern Queensland, Toowoomba, Australia, Ph: 61 (0)7 46312727, Email: downsn@usq.edu.au  Abstract.  A method for the three dimensional representation of erythemally effective ultraviolet radiation (UVery) incident to the human body has been developed from a series of polysulphone dosimeter (PS) measurements to the face, neck, arms, legs and hands of a manikin model. The technique has been used to represent a series of human UVery exposure patterns in the solar zenith angle (SZA) range 30o-50o measured in an open environment in Toowoomba, Australia (27.5oS 151.9oE). The human body representations of exposure presented here improve upon existing techniques to represent the UVery exposure to complex body shape topography, providing for the first time, estimates of exposure that take whole body shading effects into account from high density PS dosimeter measurements. Introduction    Solar UV induced exposures to the human body have previously been measured extensively using PS film badges placed on manikin and human subjects (Diffey, Tate and Davis 1979; Rosenthal et al. 1990; Kimlin Parisi and Wong 1998). This previous research has measured UV exposure at a limited number of locations. Variations in human topography, especially to regions such as the face, however, have made the accurate estimate of UVery surface distribution difficult without the extensive collection of measurements made over a large number of closely spaced body sites. An alternative approach has been to measure exposure at surfaces oriented in various planes relative to the horizontal plane (Hoeppe et al. 2004), however such approaches require taking into account the influence of body shading to specific sites. The approach presented here utilises measurements of the UVery exposure with PS dosimeters from an extensive number of body sites to provide contours of the UVery exposures. These are weighted with body topography and improve upon techniques, such as simple linear interpolation, to estimate exposure over widely spaced measurement sites. Polysulphone UVery exposure measurement    PS dosimeters having a response to UV radiation similar to human skin, (Davis, Deane and Diffey, 1976) measuring 10x15 mm with a clear circular aperture of 6 mm were manufactured from PS film cast to an approximate thickness of 40 µm at the University of Southern Queensland and mounted to flexible frames to fit life size manikin models. Changes in PS dosimeter optical absorbency measured at 330 nm were calibrated to the erythemally weighted spectral response:   ∫ ∫= T UV0ery dtd)(A)t,(SUV λλλ   Spectral measurement uncertainty in instrument stability and wavelength response has been determined at 6.3% (Parisi and Downs 2004). Calibrated UVery exposure has been represented on a three dimensional contour wireframe representation of the exposed manikin. The UVery exposure as a percentage of the received horizontal plane ambient (ER) has also been determined and calculated using the approximation of Diffey (1989):  100)9()9(3302330333033023303330 ×Δ+Δ+ΔΔ+Δ+Δ=horhorhor AAAAAAER      The calibrated UVery exposure and ER values were determined by the placement of a high density network of PS film dosimeters measured across the face, neck, arms, legs and hands, regions known to suffer long term skin defects (Lee 1989). UVery exposure was then represented as a series of coloured contours in three dimensional space over each of these body regions. Figure 1 depicts arm ER contours measured over the SZA range 45o-42o on 30 April 2007.     Figure 1.  Photographed manikin arm dosimeter sites (left) and three dimensional model exposure contours (right). ER was measured for the arm in a vertical position (alongside the manikin as photographed). The ER depicted here ranges from 0 to 51% (dark to light) of the measured horizontal plane UVery exposure.  Specific ER colour levels represented along exposure contours ranging from 0 to 100% are interpolated between measured dosimeter sites. Each interpolation between adjacent measurement sites consists of 5 evenly spaced coloured segments and is represented accordingly:  ⎟⎠⎞⎜⎝⎛ −+= − 51BAxx ii  where points A and B represent the measured ER at two adjacent sites located at contour mesh intersections on the model wireframe and values x1 through x4 are spaced evenly in the adjacent dosimeter site interval (Figure 2). The exposure ratio level (ER) and subsequent colour assigned to each of the 5 segments spaced between measurement sites is calculated as the average of the value assigned to each segment xi and x(i+1), represented in the range x1 through x4.     Figure 2.  Exposure contours and representative colour ER segment divisions interpolated between two adjacent measurement sites, A and B are highlighted in the figure. For the case shown here, points A and B are separated by approximately 5 mm and represent ER to the forehead.  Solar UV Exposure Environment     For the study results presented here, exposure to the manikin model was recorded for a general case only. Due to high density spacing of PS dosimeters, measurements to each of the face, neck, arm, hand and leg models were often not recorded at each adjacent dosimeter measurement site (see Figure 1) during exposure. Rather, experimental UVery exposure, expressed as a percentage of the horizontal plane ambient UV was recorded under clear sky conditions within the SZA range 30o-50o and was collated with further ER data measured within the SZA range to complete a contour network. Exposures were recorded at the same open location in Toowoomba and extended from between 1 and 4 hours, provided clear sky conditions and the SZA remained within the 30o-50o limit. The measurement location at the University of Southern Queensland is located at an altitude of approximately 693 m and located within the city of Toowoomba (population approximately 100,000), experiencing limited pollution, low aerosol concentrations and a high number of sunshine days. The ER contour representations presented in this research are therefore complete for the stipulated general case only, however, the technique presented may be applied to other manikin models in different locations and under different exposure conditions. The results presented, minimise the interpolation estimates of Downs and Parisi (2007) developed previously for the face and provide reasonable estimates of human body UVery exposure distribution that may be applied in other research applications.  Conclusion     Detailed solar UV induced exposures to a manikin model have been measured in a series of clear sky experiments conducted over the SZA range of 30o-50o. A technique for the estimation of exposure to body parts has been developed that can be applied in other research applications such that body surface exposures can be estimated in accordance with changing topography. Further applications of the developed technique may include modelling of UVery exposure patterns to the human body with variation in body position relative to changes in SZA, atmospheric conditions, the surrounding environment and different forms of personal solar UV protection.      Acknowledgments   The authors would like to thank the USQ technical staff for their assistance with this project.    References  Davis, A., G..H.W. Deane, B.L. Diffey, Possible dosimeter for ultraviolet radiation, Nature, 261, 169-170, 1976. Diffey, B.L., Ultraviolet radiation dosimetry with polysulphone film, Radiation measurement in Photobiology, edited by B.L. Diffey, pp. 135-159, Academic Press, London, 1989. Diffey, B.L., T.J. Tate, A. Davis, Solar dosimetry of the face: the relationship of natural ultraviolet exposure to basal cell carcinoma localization, Phys. Med. Biol., 24, 931-939, 1979.  Downs, N.J., A.V. Parisi, Three dimensional visualisation of human facial exposure to solar ultraviolet, Photochem. Photobiol. Sci., 6, 90-98, 2007. Hoeppe, P., A. Oppenrieder, C. Erianto, P. Koepke, J. Reuder, M. Seefeldner, D. Nowak, Visualisation of UV exposure of the human body based on data from a scanning UV-measuring system, Int. J. Biomet., 49, 18-25, 2004. Kimlin, M.G., A.V. Parisi, J.C.F. Wong, The facial distribution of erythemal ultraviolet exposure in south-east Queensland, Phys. Med. Biol., 43, 231-240, 1998. Lee, J.A.H., Health Outcomes of non melanoma skin cancer, Trans. Menzies Foundation, 15, 109-112, 1989. Parisi, A.V., N.J. Downs, Cloud cover and horizontal plane eye damaging solar UV exposures, Int. J. Biomet., 49, 103-136, 2004. Rosenthal, F.S., R.A. Law, L.J. Rowleau, M. Thomson, Ultraviolet exposure to children from sunlight: a study using personal dosimetry, Photodermatol. Photoimmunol. Photomed., 7, 77-81, 1990.       

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Health Outcomes of non melanoma skin cancer,

Possible dosimeter for ultraviolet radiation,

Solar dosimetry of the face: the relationship of natural ultraviolet exposure to basal cell carcinoma localization,

Ultraviolet exposure to children from sunlight: a study using personal dosimetry,

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Patterns in surface distribution of human exposure to solar ultraviolet

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Patterns in surface distribution of human exposure to solar ultraviolet

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