Ultraviolet Irradiance Research Articles

Modeling Horizontal Ultraviolet Irradiance for All Sky Conditions by Using Artificial Neural Networks and Regression Models

In the present study, different models constructed with meteorological variables are proposed for the determination of horizontal ultraviolet irradiance (IUV), on the basis of data collected at Burgos (Spain) during an experimental campaign between March 2020 and May 2022. The aim is to explore the effectiveness of a range of variables for modelling horizontal ultraviolet irradiance through a comparison of supervised artificial neural network (ANN) and regression model results. A preliminary feature selection process using the Pearson correlation coefficient was sufficient to determine the variables for use in the models. The following variables and their influence on horizontal ultraviolet irradiance were analyzed: horizontal global irradiance (IGH), clearness index (kt), solar altitude angle (α), horizontal beam irradiance (IBH), diffuse fraction (D), temperature (T), sky clearness (ε), cloud cover (Cc), horizontal diffuse irradiance (IDH), and sky brightness (Δ). The ANN models yielded results of greater accuracy than the regression models.

Statistical Properties of Plateau‐Like Turbulence Spectra in the Martian Magnetosheath: MAVEN Observations

AbstractThe Martian magnetosheath provides us with a natural laboratory to study plasma turbulence in the presence of pickup ions and locally generated instabilities. Unlike the typical magnetic‐field spectra with a single spectral scaling at magnetohydrodynamics (MHD) scales in Earth's magnetosheath, the magnetic‐field spectra in the Martian magnetosheath during 4 years of Mars Atmosphere and Volatile EvolutioN observations frequently present an additional spectral break‐point with a shallow slope at MHD scales which we define as a plateau‐like spectral feature. The average occurrence rate of plateau‐like magnetic‐field spectra is 56.6% of our measurement intervals. At moderate pick‐up angles, the occurrence rate increases to a maximum of ∼70.0%. Furthermore, we present a positive correlation with the local ion density and anti‐correlations with the local βi and the solar Extreme Ultra Violet irradiance. A similar occurrence rate in the quasi‐perpendicular and the quasi‐parallel magnetosheath (60.1% vs. 52.9%) indicates that the plateau‐like spectra are more likely formed locally than in the upstream solar wind. Our results suggest that energy injection from pickup ion driven micro‐instabilities, for example, in the form of proton cyclotron waves, has insufficient time to evolve into a fully developed cascade in such a confined space like the Martian magnetosheath.

Simultaneous Measurement of Ultraviolet Irradiance and Temperature by Employing Optical Fiber SPR Sensor With Ag/ZnO/PDMS Coating

It is a challenging and valuable work to design and manufacture temperature-compensated all-fiber ultraviolet (UV) sensor. In this article, we creatively use a simple and compact optical fiber sensor based on surface plasmon resonance (SPR) for simultaneous detection of UV and ambient temperature. Different coatings [Ag/polydimethylsiloxane (PDMS) and Ag/ZnO/PDMS] are used to split a length of no-core optical fiber (NCF) into two sensing regions, which generates a transmission spectrum with two distinct SPR dips. The proposed sensor achieves a temperature sensitivity of −2.542 nm/°C in the 15 °C–35 °C range and a UV sensitivity of −0.605 nm/(mW/cm2) in the range of 0–17.20 mW/cm2. The matrix established by the wavelength shift of two dips can demodulate UV and temperature changes, and provide temperature compensation for UV detection. In addition, even in surroundings of complex and changeable UV intensity and ambient temperature, the sensor shows excellent stability and repeatability, as well as great potential in UV sensing, providing a reference for the development of multiparameter optical fiber sensors.

Design and Construction of Ultraviolet and Incoming Solar Irradiance Sensing Device

In-situ measurements of ultraviolet (UV) and solar irradiance is very sparse in Nigeria because of cost; it is estimated using meteorological parameters. In this work, a low-cost UV and pyranometer device, using locally sourced materials, was developed. The instrument consists of a UV sensor (ML8511), a photodiode (BPW34) housed in a carefully sealed vacuumed glass bulb, the UV and solar irradiance sensor amplifiers, a 16-bit analog-to-digital converter (ADS1115), Arduino mega 2560, liquid crystal display (LCD) and microSD card for data logging. The designed amplifier has an offset voltage of 0.8676 mV. The sensitivity of the irradiance device is 86.819 Wm-2/mV with a correcting factor of 27.77 Wm-2 and a maximum range of 1200 Wm-2. The instrument validation error is 9.67% and a correlation coefficient of 0.89 when compared with a standard SRS100 pyranometer. The UV sensor showed a close response with a correlation of 0.99 in comparison with a standard Skye instrument. From 08:00 to 16:00 local time (LT), there is a very close agreement between the standard device and the developed counterpart, with marginal differences of about 9.6% observed at the two extremes.

Quality checks procedure for erroneous measurements detection of spectral components of solar irradiances

The shortwave solar radiation that arrives under the Earth's surface is spectrally composed of the ultraviolet, photosynthetically active, and near-infrared components. Having information about the availability of these parameters in different locations allows public agencies and scientific institutions to plan, execute, and manage energy projects in Brazil. Therefore, this information can be obtained from weather measurements with wide temporal and spatial coverage. However, the solar radiation measuring process is not an easy task, due to the uncertainties caused by instrumentation and operational problems. Thus, the aim of this study was to implement a procedure for erroneous measurements detection of ultraviolet, photosynthetically active, and near-infrared solar irradiances, collected in Botucatu (SP) - Brazil during the years 2001 to 2006, in sub-hourly temporal resolution (5 minutes in Wm-2), to certify the quality of the obtained measured values. For this purpose, analyzes were carried out by two quality check analyzes, the first one to verify whether the measurements were within physically possible limits and the second one whether they were within extremely rare but accepted limits. It was possible to identify that the near-infrared solar irradiance had the highest number of erroneous measurements flagged (0.310% of the total values), followed by photosynthetically active (0.162% of the total values) and, with less flags, from ultraviolet (0.047% of the total values). Measurements of spectral components of solar irradiances that were not flagged as erroneous by the quality checks procedure are considered valid, and can be used in future scientific investigations.

A rheological approach for measuring cure depth of filled and unfilled photopolymers at additive manufacturing relevant length scales

We introduce a novel experimental method that uses an ultraviolet (UV) photorheometer to enable accurate and repeatable measurements of cure depth for a wide range of photopolymers. When exposed to UV irradiation within the rheometer, the cured thickness of the photoresin is measured by lowering the upper plate while monitoring the commensurate axial force. The encoder-measured distance is correlated with axial force to measure cure depth under different UV curing conditions. This technique enables precise measurements of photocured films thinner than 50 µm, which can then be used to establish working curve equations for photopolymerization-based additive manufacturing (AM) processes. This process is validated through the evaluation of three unique photoresins, including a commercially available VP stiff photoresin, a highly-viscous photoresin that cures into a “soft” gel, and a highly solids-loaded photoresin with particles that greatly limit maximum cure depth. In addition, the technique is employed to explore the impact of UV irradiance on curing behavior of photoresins. This technique enables measurement of AM process-relevant cure depths with process-relevant irradiance and wavelengths and has applications in advanced material development for a range of AM and traditional UV processing technologies. This technique meets identified gaps in current cure depth characterization techniques, including the need for automated instrumental approaches to reduce human error in measurements, the need to directly measure cure depths less than 150 µm, and the need to measure curing behavior at different UV irradiances/wavelengths. Due to the non-linear cure depth versus exposure behavior of some photoresins, it is important to directly measure cure depths at AM process-relevant sizes ( µm), as a working curve made from measurements of thicker films leads to more inaccurate predictions than those made from measuring thinner films.

Self-powered electrochemical wide-band photodetectors using ZrO2@TiO2 nanorod arrays modified with single-walled carbon nanotubes

Self-powered broad-band electrochemical photodetectors (ECPDs) based on broadband photoresponse nanostructured composites are a low-cost and promising photoelectrochemical (PEC) device. In this work a TiO 2 nanorod array (TNRA) structure modified by the ZrO 2 nanoparticles and metallic single-walled carbon nanotubes (m-SWCNTs) was used to prepare the ECPDs for enabling a high performance ultraviolet-visible (UV-VIS) photoresponse. The ECPDs exhibit a high optical sensitivity with an on/off ratio of 1.59 × 10 5 and an optical responsivity of 158.67 mA/W under ultraviolet radiation (365 nm) without external bias. The lowest detectable intensity of ultraviolet and visible-light irradiance (465 nm) can reach around 0.1 mW/cm 2 and 0.18 mW/cm 2 . The enhanced PEC performance can be attributed to the effective separation and transport of carriers in the PEC system by the type-I band alignment of ZrO 2 @TiO 2 structure and high conductive network of SWCNTs.

Effect of Ultraviolet Radiation on Reducing Airborne Escherichia coli Carried by Poultry Litter Particles.

Airborne Escherichia coli (E. coli) originating in poultry houses can be transmitted outside poultry farms through the air, posing risks of barn-to-barn infection through airborne transmission. The objective of this study is to examine the effect of ultraviolet (UV) light on the inactivation of airborne E. coli carried by poultry dust particles under laboratory conditions. A system containing two chambers that were connected by a UV scrubber was designed in the study. In the upstream chamber of the system, airborne E. coli attached to dust particles were aerosolized by a dry aerosolization-based system. Two sets of air samplers were placed in the two chambers to collect the viable airborne E. coli. By comparing the concentration of airborne E. coli in the two chambers, the inactivation rates were calculated. The airborne E. coli inactivation rates were tested at different contact times with the aid of a vacuum pump (from 5.62 to 0.23 s of contact time) and different UV irradiance levels (of 1707 µW cm-2 and 3422 µW cm-2). The inactivation rates varied from over 99.87% and 99.95% at 5.62 s of contact time with 1707 µW cm-2 and 3422 µW cm-2 of UV irradiance to 72.90% and 86.60% at 0.23 s of contact time with 1707 µW cm-2 and 3422 µW cm-2 of UV irradiance. The designed system was able to create the average UV irradiation of 1707 µW cm-2 and 3422 µW cm-2 for one UV lamp and two UV lamps, respectively. The findings of this study may provide an understanding of the effect of UV light on the inactivation of airborne E. coli carried by dust particles and help to design an affordable mitigation system for poultry houses.

Enhanced photocatalytic activity of ceria-doped zinc oxide under UV illumination prepared via chemical precipitation.

Transition metal oxide has emerged as one of the most potential candidates for environment remediation by utilizing solar energy through photocatalysis. This study compares the optical characteristics of zinc oxide (ZnO) and ceria-doped zinc oxide (CeZnO) nanoparticles synthesized through a facile chemical precipitation method without using any assistant catalyst. The present work investigates the consequences of ceria (cerium dioxide, CeO2 ) intrusion on the photocatalytic activity of ZnO nanoparticles using methylene blue (MB) as a probe pollutant. The CeZnO showed an increase in photoactivity when compared to ZnO nanoparticles for degradation of MB in an aqueous solution under ultraviolet (UV) irradiance. The resulting heterojunction between ZnO and that of ceria enhances the charge separation efficiency showing a strong correlation between ZnO and CeO2 heterojunction on the charge transfer mechanism across the interface.

Predicting spatial distribution of ultraviolet irradiance and disinfection of exhaled bioaerosols with a modified irradiance model

The transmission of airborne infectious diseases in indoor environments has become a major public health concern. Ultraviolet C lights are effective in inactivating bioaerosols to reduce infection risks. To facilitate the design and application of UVC systems, this study developed a modified irradiance model for calculating the spatial irradiance distribution when unstructured meshes are used for arbitrary reflective surfaces. With the modified irradiance model, the computational fluid dynamics (CFD)-Eulerian model was used to predict the dispersion and UV disinfection of bioaerosols. The proposed model was first preliminarily validated using measured data for in-duct ultraviolet germicidal lamps from the literature. For further validation of the proposed model in a relatively complex environment, experimental measurements of the detailed spatial irradiance distribution and bioaerosol concentration exhaled from a manikin in a ventilated chamber with a far UVC lamp were compared with calculated results. It was found that the proposed modified irradiance model can predict the spatial irradiance distribution reasonably well when unstructured meshes are used for arbitrary reflective surfaces. Furthermore, the modified irradiance model with the CFD-Eulerian model can predict the dispersion and UV disinfection of exhaled bioaerosols in indoor environments reasonably well. Finally, the validated model was used to predict person-to-person influenza A virus transport in a room with a ventilation rate of 3 ACH and a far UVC lamp with an effective output power of 0.34 W. The results show that the far UVC lamp can effectively reduce the receptor's exposure to influenza A virus by 65%.

The prognostic implication of latitude in uveal melanoma: a nationwide observational cohort study of all patients born in Sweden between 1947 and 1989

BackgroundThe incidence of uveal melanoma increases with latitude. In this study, we examine the importance of latitude for uveal melanoma prognosis.MethodsAll uveal melanoma patients born in Sweden between 1947 and 1990 were included (n = 745). The latitude of patients’ birthplaces and home counties at the time of uveal melanoma diagnosis were collected. For all latitudes, data on sunlight and UV intensity parameters, temperature, daytime length variations, and socioeconomic factors were added. The prognostic implication of birthplace latitude and of moving > 1 degree of latitude was examined with multivariate Cox regressions and competing risk analyses.FindingsThere were no significant differences in patient sex, age, tumor size, T-category, or BAP-1 immunoexpression between patients born in the south, central or northern regions of Sweden. Decreasing birthplace latitude was a predictor of uveal melanoma-related mortality in multivariate Cox regression. Patients that were born in southern regions or moved > 1 degree south between birth and diagnosis had higher incidence of uveal melanoma-related mortality in competing risk analysis. The sum of yearly sunshine hours, global sunlight radiation, average daily ultraviolet light intensity, average annual temperature, or net wealth were not predictors of uveal melanoma-related mortality.InterpretationLatitude is a prognostic factor in uveal melanoma. This does not seem to be related to variations in patient or tumor characteristics at presentation, in management, in sunlight intensity, in ultraviolet light irradiance, in temperature, or in wealth. Future studies should examine if periodical changes in daylight hours or other factors could explain the prognostic implication.

Solar Ultraviolet Irradiance Characterization under All Sky Conditions in Burgos, Spain

Solar Ultraviolet Radiation (UVR), which is identified as a major environmental health hazard, is responsible for a variety of photochemical reactions with direct effects on urban and aquatic ecosystems, human health, plant growth, and the deterioration of industrial systems. Ground measurements of total solar UVR are scarce, with low spatial and temporal coverage around the world, which is mainly due to measurement equipment maintenance costs and the complexities of equipment calibration routines; however, models designed to estimate ultraviolet rays from global radiation measurements are frequently used alternatives. In an experimental campaign in Burgos, Spain, between September 2020 and June 2022, average values of the ratio between horizontal global ultraviolet irradiance (GHUV) and global horizontal irradiance (GHI) were determined, based on measurements at ten-minute intervals. Sky cloudiness was the most influential factor in the ratio, more so than any daily, monthly, or seasonal pattern. Both the CIE standard sky classification and the clearness index were used to characterize the cloudiness conditions of homogeneous skies. Overcast sky types presented the highest values of the ratio, whereas the clear sky categories presented the lowest and most dispersed values, regardless of the criteria used for sky classification. The main conclusion, for practical purposes, was that the ratio between GHUV and GHI can be used to model GHUV.

The dependence of Martian ion escape on solar EUV irradiance as observed by MAVEN

We analyze the planetary ion, solar wind, interplanetary magnetic field (IMF), and solar extreme ultraviolet (EUV) irradiance data from the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) mission to quantify the variation in ion escape with solar EUV irradiance. With relatively strict constraints on the upstream solar wind and IMF conditions, we divide the planetary ion data into 4 subsets with different solar EUV conditions to estimate ion escape rates. The results show that the total ion escape rate may increase nonlinearly with solar EUV irradiance and eventually approach an asymptotic limit as EUV increases. Further analysis on different ion species, escape channels, and energy ranges show that the dependence on solar EUV varies between these different ion populations. We also find that the spatial distributions of ion density and velocity vary between high and low solar EUV conditions, which is likely caused by the variations of electromagnetic field distributions. These results suggest that as solar EUV controls the ion production and affects the ion distributions near Mars, it will in turn influence the electromagnetic field distributions and thus affect the acceleration of escaping ions. This feedback mechanism may limit the total ion escape rate as solar EUV increases under constrained solar wind and IMF conditions.

Energy dependent response of the dayside Martian ionospheric electrons to solar forcing

We study the response of Auger electrons, He-II photoelectrons, and thermal electrons in the dayside Martian ionosphere to the solar soft X-rays (SXR; 0.1–7 nm), 30.5 nm, and the extreme ultraviolet (EUV; 20–90 nm) irradiances, respectively. For this purpose, the suprathermal electron fluxes measured by the Solar Wind Electron Analyzer (SWEA) and densities of the thermal electrons measured by Langmuir Probe and Waves (LPW) instruments, both on the Mars Atmosphere and Volatile Evolution (MAVEN) mission, have been used. The data used in the present study span from January 2015 (Martian Year (MY) 32, solar longitude, Ls = 263°) to December 2019 (MY 35, Ls = 110°), which falls in the declining phase of solar cycle 24. The solar irradiances are taken from the extreme ultraviolet monitor instrument on MAVEN and also from the Flare Irradiance Spectral Model for Mars. The results of the present study show that the fluxes of the suprathermal electrons and the densities of the thermal electrons are drastically reduced during solar minimum. The Auger electrons show a significant correlation and have an almost linear relationship with the SXR irradiance; both of which are independent of altitude. The response of the He-II photoelectrons to 30.5 nm solar irradiance deviates slightly from the linear relationship, particularly in the altitude range of 225–350 km and the solar zenith angle (SZA) range of 45°-65°. At these altitude and SZA ranges, the thermal electrons show a power law dependence on the EUV irradiance. The responses of the He-II photoelectrons and thermal electrons to their respective solar irradiances decrease on either side of the altitude and SZA range of maximum response (225–350 km and 45°-65°, respectively). The energy dependent response of the electrons to the solar irradiances and their altitude and SZA variation are explained by considering their dependence on electron temperature, and ionization and the neutral heating efficiencies. The responses of the He-II photoelectrons and thermal electrons to their respective solar irradiances decrease near the terminator.

Disinfection performance of an ultraviolet lamp: a CFD investigation

Ultraviolet (UV)-based devices have shown their effectiveness on various germicidal purposes. To serve their design optimisation, the disinfection effectiveness of a vertically cylindrical UV lamp, whose wattage ranges from P = 30 − 100 W, is numerically investigated in this work. The UV radiation is solved by the Finite Volume Method together with the Discrete Ordinates model. Various results for the UV intensity and its bactericidal effects against several popular virus types, i.e., Corona-SARS, Herpes (type 2), and HIV, are reported and analysed in detail. Results show that the UV irradiance is greatly dependent on the lamp power. Additionally, it is indicated that the higher the lamp wattage employed, the larger the bactericidal rate is observed, resulting in the greater effectiveness of the UV disinfection process. Nevertheless, the wattage of P ≤ 100W is determined to be insufficient for an effective disinfection performance in a whole room; higher values of power must hence be considered in case intensive sterilization is required. Furthermore, the germicidal effect gets reduced with the viruses less sensitive to UV rays, e.g, the bactericidal rate against the HIV virus is only ∼8.98% at the surrounding walls.

Regulation of Exposure to Ultraviolet Light in Bearded Dragons (Pogona vitticeps) in Relation to Temperature and Scalation Phenotype

Exposure to ultraviolet (UV) light has both physiological benefits as well as costs. Many lepidosaur reptiles can behaviorally self-regulate their exposure to UV light in order to take advantage of the benefits of UV light while minimizing the costs. Furthermore, lepidosaur scales have been conceptualized by some as a barrier to the penetration of UV light. Here we examine regulation of self-exposure to UV light in three different phenotypes of Bearded Dragon (Pogona vitticeps): wild type, animals exhibiting scales of reduced prominence (‘Leatherback’), and scaleless animals (‘Silkback’). Silkbacks on average chose to expose themselves to lower levels of UV light irradiation than Leatherbacks or wild types did. Bearded Dragons of all scalation phenotypes on average received higher UV irradiation when they were in the cold section of a UV gradient apparatus compared to when they were in the hot section of the apparatus. This either demonstrates that Bearded Dragons under higher UV irradiances choose cooler temperatures or demonstrates that Bearded Dragons at cooler temperatures choose higher UV irradiances. The relationship between chosen temperature and chosen UV light irradiance was not affected by scalation phenotype. This study highlights external influences on the mechanism that regulates UV self-exposure behavior in lepidosaur reptiles.

Relationship between ozone and biologically relevant UV at 4 NDACC sites.

Clouds and aerosols, as well as overhead ozone, can have large effects on ultraviolet (UV) irradiances. We use statistical methods to remove cloud effects and mean aerosol effects from spectral UV irradiance measurements to investigate the relationship between UV and total column ozone. We show that for fixed solar zenith angles (SZA), seasonal changes in ozone lead to marked changes in clear-sky UV irradiances. Such effects are larger at mid-latitudes than in the tropics. At mid-latitudes, the minimum ozone amount over the course of a year can be about 50 percent of its maximum, with the lowest values in autumn and the highest values in spring. These seasonal ozone changes lead to UV Index (UVI) values in autumn that can exceed those in spring at the same SZA by nearly a factor of two. Differences are even larger for UV spectra weighted by the action spectra for DNA-damaging UV, and for cutaneous previtamin D production. In some cases, the seasonal increase exceeds a factor of 4. The analysis experimentally demonstrates the limits of applicability of the concept of constant Radiative Amplification Factors (RAFs) for estimating effects of changes in ozone for some weighting functions. Changes in DNA-weighted UV and erythemally weighted UV are well represented by the published RAFs. However, there are large SZA dependencies in the case of UVB and vitamin D-weighted UV. For all weightings considered, RAFs calculated from the observations as a function of SZA show similar dependencies between sites, in good agreement with published values, independently of the ozone data source. High quality measurements show that natural variations in ozone are responsible for huge variations in biologically damaging UV, with seasonal changes at fixed solar zenith angles sometimes exceeding a factor of four. The measured changes from thousands of spectra agree well with calculations over a wide range of solar zenith angles.

Is ultraviolet Radiation a Confounding Variable for COVID-19 in India?

The current global Coronavirus disease (COVID-19) became a pandemic due to its contagion nature and rapid spread throughout the world. The pandemic caused a lockdown resulting in a large decline in the level of anthropogenic emissions of tiny aerosol particles that altered the solar irradiance and decreased the quantity of aerosol, which opposes global warming. This study first demonstrates that surface ultraviolet radiation (UV) increased significantly during the lockdown period in four major Indian mega cities, whose magnitude varies based on city demography. Results shows that the correlation between the high rate of increase in Ultraviolet irradiance (UV-irradiance) on mortality and morbidity. Although there are numerous confounding factors for the pandemic, UV-irradiance could be one of the factors supporting the hypothesis that increased solar UV dose may increase rate of disinfection as radiation warps the structure of genetic material of the virus and deactivates it. Another factor which also have potential to add up increase of Vitamin D3 production per minute of exposure due to UV-irradiance resulting in an increased human immune system to fight COVID-19 more effectively. However, it is cautioned here that a high dose of direct UV exposure to humans may be fatal leading to skin damage and melanoma cancer. Hence, the harmful impact of UV-Irradiance on the human body and its application to possible disinfectant to virus deactivation should be understood in a proper perspective.

Is ultraviolet Radiation a Confounding Variable for COVID-19 in India?

The current global Coronavirus disease (COVID-19) became a pandemic due to its contagion nature and rapid spread throughout the world. The pandemic caused a lockdown resulting in a large decline in the level of anthropogenic emissions of tiny aerosol particles that altered the solar irradiance and decreased the quantity of aerosol, which opposes global warming. This study first demonstrates that surface ultraviolet radiation (UV) increased significantly during the lockdown period in four major Indian mega cities, whose magnitude varies based on city demography. Results shows that the correlation between the high rate of increase in Ultraviolet irradiance (UV-irradiance) on mortality and morbidity. Although there are numerous confounding factors for the pandemic, UV-irradiance could be one of the factors supporting the hypothesis that increased solar UV dose may increase rate of disinfection as radiation warps the structure of genetic material of the virus and deactivates it. Another factor which also have potential to add up increase of Vitamin D3 production per minute of exposure due to UV-irradiance resulting in an increased human immune system to fight COVID-19 more effectively. However, it is cautioned here that a high dose of direct UV exposure to humans may be fatal leading to skin damage and melanoma cancer. Hence, the harmful impact of UV-Irradiance on the human body and its application to possible disinfectant to virus deactivation should be understood in a proper perspective.

Generalized Kubelka's theory for light transmission in multilayer materials and its application for UV light penetration in filtering facepiece respirators.

The spread of SARS‐CoV‐2 has resulted in the shortage of filtering facepiece respirators (FFRs). As a result, the use of ultraviolet (UV) irradiation for disinfection and reuse of FFRs has been the topic of much investigation. In this article, a mathematical model is developed based on Kubelka's theory to determine light transmission in multilayer materials, such as N95 masks. Using this model, the predicted UV transmittance and absorbance of a N95 mask layers were found to be in close agreement with the experimental values. In addition, when the mask was exposed to UV equally from both surfaces, the estimated minimum UV irradiance inside the N95 mask was 14.5% of the incident irradiance, suggesting a significant degree of light penetration. The proposed model provides a simple and practical methodology for the design and use of UV decontamination equipment for FFRs and other multilayer materials.