Direct comparison between the angular distributions of the erythemal and eye-damaging UV irradiances: A pilot study

School of Engineering, Griffith University, Gold Coast, Australia.
Journal of photochemistry and photobiology. B, Biology (Impact Factor: 2.96). 02/2011; 102(2):146-55. DOI: 10.1016/j.jphotobiol.2010.11.001
Source: PubMed


Several broadband ultraviolet (UV) radiation angular distribution investigations have been previously presented. As the biologically damaging effectiveness of UV radiation is known to be wavelength dependent, it is necessary to expand this research into the distribution of the spectral UV. UV radiation is also susceptible to Rayleigh and Mie scattering processes, both of which are completely wavelength dependent. Additionally, the majority of previous measurements detailing the biologically damaging effect of spectral UV radiation have been oriented with respect to the horizontal plane or in a plane directed towards the sun (sun-normal), with the irradiance weighted against action spectra formulated specifically for human skin and tissue. However, the human body consists of very few horizontal or sun-normal surfaces. Extending the previous research by measuring the distribution of the spectral irradiance across the sky for the complete terrestrial solar UV waveband and weighting it against erythemal, photoconjunctivital and photokeratital action spectra allowed for the analysis of the differences between the biologically effective irradiance (UV(BE)) values intercepted at different orientations and the effect of scattering processes upon the homogeneity of these UV(BE) distributions. It was established that under the local atmospheric environment, the distribution profile of the UV(BE) for each biological response was anisotropic, with the highest intensities generally intercepted at inclination angles situated between the horizontal and vertical planes along orientations closely coinciding with the sun-normal. A finding from this was that the angular distributions of the erythemal UV(BE) and the photoconjunctivital UV(BE) were different, due to the differential scattering between the shorter and longer UV wavelengths within the atmosphere.

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Available from: Alfio V. Parisi, Oct 26, 2014
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    • "The damage can be felt as a sharp pain in the eyes. Because new cornea and conjunctiva cells constantly re-grow, the damage is reversible [10] "

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    ABSTRACT: A number of previous studies have discussed the risk of eye damage from broadband ultraviolet (UV) radiation. As the biologically damaging effectiveness of UV irradiation on the human body is known to be wavelength-dependent, it is necessary to study the distribution of the UV spectral irradiance. In order to quantify the ocular biologically effective UV (UVBE) irradiance exposure of different wavelengths and assess the risk of eye damage, UV exposure values were measured at Sanya, China (18.4° N, 109.7°E, altitude 18 m), using a manikin and a dual-detector spectrometer to measure simultaneously the ocular exposure and ambient UV spectral irradiance data and solar elevation angle (SEA) range (approximately 7°-85°). The present study uses the ocular UV spectral irradiance exposure weighted with the action spectra for photokeratitis, photoconjunctivitis and cataracts to calculate the ocular UVBE irradiance exposure for photokeratitis (UVBE(pker)), photoconjunctivitis (UVBE(pcon)) and cataracts (UVBE(cat)). We found that the ocular exposure to UV irradiance is strongest in the 30°-60° SEA range when ∼50% of ocular exposure to UV irradiance on a summer's day is received. In the 7°-30° SEA range, all the biologically highly effective wavelengths of UVBE(pker), UVBE(pcon) and UVBE(cat) irradiances are at 300 nm. However, in other SEA ranges the biologically highly effective wavelengths of UVBE(pker), UVBE(pcon) and UVBE(cat) irradiances are different, corresponding to 311 nm, 300 nm and 307 nm, respectively.
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