Abstract
The inactivation of pathogens through the irradiation of ultraviolet light depends on how light propagates within the medium where the microorganism is immersed. A simple geometrical optics analysis, and a fluence evaluation reveal some reservoirs where the pathogen may hide and be weakly exposed to the incoming radiation. This geometrical hide-outs also generate a tail in the plot of the total inactivation plot vs. the incoming fluence. We have analyzed these facts using geometrical optics principles and illumination engineering computational packages. The results obtained from previous biomedical measurements involving SARS-CoV-2 have been used to evaluate the inactivation degree for an spherical geometry applicable to airborne pathogens, and for an spherical cap geometry similar to that used in biomedical experiments. The case presented here can be seen as the worst-case scenario applicable under collimated illumination.
Highlights
Triggered by the onset of the Covid19 pandemic, several strategies to disinfect pathogens have been revisited and applied to inactivate the SARS-CoV-2 [1,2,3,4,5,6]
The results obtained from previous biomedical measurements involving SARS-CoV-2 have been used to evaluate the inactivation degree for an spherical geometry applicable to airborne pathogens, and for an spherical cap geometry similar to that used in biomedical experiments
Previous studies have determined the characteristic fluence for inactivation of the SARS-CoV-2 at λ = 254 nm
Summary
Triggered by the onset of the Covid pandemic, several strategies to disinfect pathogens have been revisited and applied to inactivate the SARS-CoV-2 [1,2,3,4,5,6]. The propagation of light within the medium is relevant to account for the disinfection level To properly address these issues, geometrical optics, ray tracing and illumination engineering design packages may help to understand better how light moves through the sample [9,14]. This local inactivation is used to analyze the exposure level of each region of the volume of interest In this contribution, we have considered a simple geometrical optics model to understand better the behavior of light for two of the geometries involving curved surfaces (Section 2).
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