Investigation of correlation of broadband UVA reflection to broadband visible reflection for a variety of surfaces in the built environment

Abstract

UVA radiation (320-400 nm) exposure is linked to detrimental health effects, including DNA damage, eye damage and impacts on immune suppression. Occupational exposure to UVA radiation could increase the risk of developing such health effects, through increased exposure from reflective surfaces. A range of surfaces have been investigated for broadband (from spectral) UVA and visible reflectance, from horizontal, inclined and vertical orientations. A selection of this data has been presented graphically. Non-metallic and coated metallic surfaces were shown to have low UVA broadband reflectance (<0.20) compared to some metallic surfaces UVA broadband reflectance (0.1-0.5). Uncoated metallic surfaces can use UVA reflectance as a function of visible reflectance, however non-coated metallic surfaces have no similar function. The metallic surface type data were used to correlate UVA broadband reflectance to visible broadband reflectance and a model developed to express UVA broadband as a function of visible reflectance. The model for zinc aluminium coated steel is a linear regression, with UVA reflectance ranging from 0.09 to 0.46 and visible reflectance ranging from 0.05 to 0.57, with an R 2 of 0.95. The reflective coefficients used to create the model were produced on a solar zenith angle (SZA) range of 18°-70.5°. The model was tested on a different dataset with a SZA range of 5.7°-62.9° on clear days and was shown to have reasonable results with an RMSE of 0.049 for prediction of UVA reflectance from visible reflectance allowing prediction of the UVA reflectance from the visible reflectance for this surface type.

Ultraviolet Radiation Albedo and Reflectance in Review: The Influence to Ultraviolet Exposure in Occupational Settings

“…In that study, the conclusion was to use the term reflection to differentiate between measurements adhering to albedo definitions and assumptions (horizontal surface) and to reflectance definitions (non-horizontal surfaces in order to compare against horizontal measurements). In a more recent paper, it was concluded that reflectance was a more appropriate term, and would continue to be, particularly given the above discussion presented here [ 21 ]. Therefore, we can conclude that unless the conditions and assumptions for albedo are satisfied (horizontal surface and assumed Lambertian reflector), it is better to use reflectance to describe the radiative transfers occurring at a surface.…”