Erythemal UV Research Articles

Evaluating the ultraviolet protection factors of urban broadleaf and conifer trees in public spaces

Urban trees provide natural shade and moderate human exposure to solar ultraviolet radiation. To date, most studies quantifying UV attenuation by urban tree canopies have taken place in Australia, with no studies in North America. Few studies have utilized sensors sensitive to UV-B radiation, although the shorter wavelengths are more important in determining erythemal (skin burning) UV. We collected solar UV radiation exposure data beneath 64 individuals of 16 tree species commonly planted in the City of Toronto's schoolyards and public parks, using UV electronic logging dosimeters that have a spectral response closely matching the erythemal action spectrum. Additional data were collected on canopy structure (crown radii, crown transparency, crown depth, diameter at breast height, height to live crown, and leaf-level data). UV protection factor (PF: the ratio of open-site UV to below-canopy UV) varied 2.6-fold among species, ranging from ∼1.3−3.4. Statistical models for variation among trees indicated that crown transparency (%), the ratio of crown breadth to height to live crown, and species shade tolerance were important predictors of PF. Acer platanoides ‘Crimson King’, Celtis occidentalis L., Quercus bicolor Willd., and Fagus sylvatica ‘Purpurea’ showed the highest PF values (>3), and Ginkgo biloba L. and Acer rubrum L. showed the lowest PF values (<2) among sampled species. Findings from this study can help inform tree management strategies and policies to increase UV protection in schoolyards and other public settings.

Relative Contributions of Clouds and Aerosols to Surface Erythemal UV and Global Horizontal Irradiance in Korea

The attenuating effects of clouds and aerosols on global horizontal irradiance (GHI) and ultraviolet erythemal irradiance (UVER) were evaluated and compared using data from four sites in South Korea (Gangneung, Pohang, Mokpo, and Gosan) for the period 2005–2016. It was found that GHI and UVER are affected differently by various attenuating factors, resulting in an increase in the ratio of UVER to GHI with a decrease in the clearness index of GHI. A comparative analysis of the clearness indices of GHI and UVER identified an almost linear relationship between two transmittances by applying UVER with fixed slant ozone ( UVER 300 ) and there was a latitudinal difference in the relationship. Some nonlinearity remained in this relationship, which suggests a contribution by other factors such as clouds and aerosols. Variations of the UVER 300 ratio to GHI with cloud cover and aerosol optical depth were analyzed. The ratio increased with cloud cover and decreased with aerosol optical depth, indicating that clouds attenuate GHI more efficiently than UVER and that the attenuation by aerosols is greater for UVER than for GHI. A multiple linear regression analysis of the clearness indices of GHI and UVER 300 quantitively demonstrates differences in the radiation-reducing effects of clouds and aerosols, with some regional differences by site that can be attributed to local climatic characteristics in South Korea.

The importance of ground-based and satellite observations for monitoring and estimation of UV radiation in Novi Sad (Serbia)

Solar ultraviolet (UV) radiation is a significant health hazard in the warm part of the year. In order to assess the level of hazard and the effects of UV radiation on the living world, long-term measured or estimated data are needed. In Novi Sad, the measurement of UV radiation has been performed since 2003, while ozone measurements have been made since 2007. However, those data sets are too short for assessing long-term biological effects. Therefore, several techniques for reconstruction of UV radiation doses have been developed. Reconstruction techniques are based on using available ground-based measurements of the meteorological data and satellite measurements of the total ozone column. It is shown that techniques that use ozone data show better performance than those that use only ground-based meteorological measurements. However, the difference between the performances of the methods is smaller when it comes to the monthly values, indicating that the techniques which use only ground-based meteorological measurements are roughly as good as the ozone-based techniques for assessing long-term changes in the surface UV radiation. The statistically significant increasing long term-trend of annual mean erythemal UV doses (ERY) and the decreasing trend in the total ozone column in Novi Sad since 1981 have been noticed. An increase in ERY has been noticed in all the seasons except in autumn and it is the highest in winter. The analysis showed that the increase in the ERY in the period 1981–1996 was mainly caused by the total ozone column, while the increase after 1996 is largely caused by cloudiness.

西藏晴天太阳红斑紫外线观测研究

西藏晴天太阳红斑紫外线观测研究

3D Modelling for Solar Erythemal UV Protection Provided by Human Hair

The head is one of the most sun-exposed anatomical zones and its ultraviolet (UV) exposure is often underestimated. The goal of this research is to quantify the solar erythemal UV protection provided by human hair for different orientations and Solar Zenith Angles (SZA). For this purpose, a three-dimensional (3D) numeric simulation tool called SimUVEx was used to forecast the distribution of UV exposure based on geometric information and solar irradiance. The relative UV dose reduction was expressed in terms of predictive protection factor (PPF). Results showed that the effectiveness of the protection depends strongly on the orientation of the head and on the tilt of the hairs. As the SZA increases, the PPF also increases. PPFs provided by hair with a certain degree of order (parallel alignment) were generally higher by a range of about 10%–30% than the ones provided by random arrangements. A significant exposure to the scalp through the hair, even for an average hair density, was found. It confirms that hair is an important natural sunscreen in reducing transmission of UV radiation and must be considered in the prevention messages of skin cancer on the scalp, particularly in people with alopecia.

Sun Exposure of Body Districts: Development and Validation of an Algorithm to Predict the Erythemal Ultra Violet Dose.

Solar Ultra-Violet (UV) radiation has positive and negative effects on human body tissues. Small doses of solar UV radiation are needed by the human skin for the activation of the vitamin D production. Overexposure to solar UV radiation can produce acute and long-term negative effects, such as sunburns and, in the worst cases, cataracts and skin cancers. For this reason, knowing the amount of UV doses received by people is essential to evaluate their risk to UV overexposure and to evaluate the adequate countermeasure to avoid the negative effects. The original contribution of the present study consists in having searched, collected, adapted and processed a series of technical information and analytical relations, developing an algorithm suitable for the calculation of the erythemal UV dose on sloped surfaces exposed to solar radiation, which at the moment is not present in the scientific literature. The results obtained by the algorithm have been compared to the results of a field measurements campaign, carried out in three different Italian sites. Results comparison indicated that measured and calculated values show a sufficient level of agreement, with a mean absolute error equal to 20%.

Occupational Exposure to Solar UV Radiation of a Group of Fishermen Working in the Italian North Adriatic Sea.

Occupational solar radiation exposure is a relevant heath risk in the fishing sector. Our aim was to provide a detailed evaluation of individual UV exposure in three different fishing activities in Italy, with personal UV dosimeters and a simple formula to calculate the fraction of ambient erythemal UV dose received by the workers. The potential individual UV exposure of the fishermen was between 65 and 542 Joules/m2. The percentages of the ambient exposure were estimated between 2.5% and 65.3%. Workers’ UV exposure was mainly influenced by the characteristics of the work activity, the postures adopted, and the type of boats. Overall, our data showed that 43% of the daily measurements could result largely above the occupational limits of 1–1.3 standard erythemal dose (i.e., 100 Joules/m2) per day, in case of exposure of uncovered skin areas. Measurements of individual UV exposure are important not only to assess the risk but also to increase workers’ perception and stimulate the adoption of preventive measures to reduce solar UV risk. Furthermore, the simple method proposed, linking ambient erythemal UV dose to the workers’ exposure, can be a promising tool for a reliable assessment of the UV risk, as time series of environmental UV dose are widely available.

The forecast of erythemal UV irradiance over the territory of Northern Eurasia according to the INM-RSHU chemical-climate model

In this work, the impact of various factors on the total ozone column and erythemal UV radiation (Qery) in the territory of Northern Eurasia for the period from 1979 to 2059 based on the calculations of the chemical-climate model INM-RHSU is analyzed. The sensitivity of ozone recovery to the setting of different input data on sea surface temperature (SST) is estimated. Depending on the SST datasets, there are significant differences in ozone trends. A possible mechanism that explains the reasons for these differences is examined. The numerical experiment with the only change in ozone depleting substances according to Montreal protocol showed the ozone recovery and, as a result, Qery reduction, but this recovery is not linear. During the 2016-2020 period we estimated the 2-5% increase in Qery values relative to the baseline period (1979-1983) with about 6% maximum over Russian polar region. During the 2035-2039 period the Qery change against 1979-1983 period is about zero, during the 2055-2059 period we obtained the decrease of about 4-6% over Northern Asia and 6-8% over Northern Europe These changes corresponded to the noticeable boundary location shift of UV resources, which determine UV radiation impact on human health. The most significant changes will be observed in spring and summer: the UV deficiency zone will be expanded in the north and the UV excess zone over northern seas will be reduced in the south.

Ultraviolet radiation exposure during daylight Photodynamic Therapy.

Daylight photodynamic therapy (dPDT) is an effective treatment for field-change actinic keratoses (AK), with similar efficacy to conventional PDT but lower patient pain scores. Whilst AK occur consequent to chronic solar ultraviolet (UV) exposure, paradoxically solar visible radiation is used during PDT. To investigate the nature and levels of UV exposure, both erythemal UV and UVA, occurring during dPDT. Four years of solar erythemally effective UV (UVE) irradiance, UVA irradiance and illuminance data were obtained from Pubic Health England for 12 locations. For a standard 2 h treatment period, the data were converted into standard erythemal doses (SEDs), UVA dose and protoporphyrin-IX (PpIX)-weighted dose from UVE irradiance, UVA irradiance and illuminance respectively. These three parameters were compared ascertaining the UV exposure received during dPDT. Analysis of UV exposure during dPDT showed a UK maximum average UVE exposure of 8.2 SED at Camborne (PpIX dose 23.4 J cm-2). Treatment earlier in the day reduces average UV exposure (Camborne 5.2 SED, PpIX dose 18.2 J cm-2), whilst PpIX dose achieves threshold during winter months (Camborne, November, 0.8 SED, PpIX dose 7.1 J cm-2). Cyprus and Gibraltar (with high UV exposure during dPDT) experience a maximum of 14.3 SED and 12.9 SED, with respective PpIX doses of 36.1 J cm-2 and 35.1 J cm-2, in June. UVA exposure is also presented for comparison. Therapeutically effective dPDT doses can be achieved at times of the day and year when UV exposure is minimal.

Numerical Simulation of Variations in Ozone Content, Erythemal Ultraviolet Radiation, and Ultraviolet Resources over Northern Eurasia in the 21st Century

The influence of different factors on the total ozone content (TOC) and erythemal UV radiation (Qery) in the atmosphere over northern Eurasia from 1979 to 2059 has been analyzed using a chemistry-climate model developed at the Institute of Numerical Mathematics (INM, Russian Academy of Sciences) and the Russian State Hydrometeorological University (RSHU). The sensitivity of modeled ozone contents to different input data on sea-surface temperature (SST) has been estimated. The TOC trends may significantly differ depending on the SSTs used. The results of the model experiment, which takes into account variations in the anthropogenic emissions of halogen-containing substances, suggest a nonlinear Qery decrease due to the recovery of the ozone layer in the 21st century. The values of Qery for 2016–2020 are 2–5% higher than its values for 1979–1983, on average, for all of northern Eurasia (with its maximum on the order of 6% in the polar latitudes). The Qery values equalize in 2035–2039 and then gradually decrease (when compared to those for 1979–1983) by 4–6% for Asia and 6–8% for northern Europe in 2055–2059. Therefore, variations are observed in the spatial distribution of UV resources, which are most significant in spring and summer: these variations are manifested in the extension of UV-deficiency zones in the north and the reduction of UV-excess zones in the south.

Erythemal UV Radiation on Days with Low UV Index Values-an Analysis of Data from the German Solar UV Monitoring Network over a Ten-year Period.

According to the World Health Organization and partner organizations, no protection against ultraviolet (UV) radiation is required on days with "low" values (i.e., values <3) of the Global Solar Ultraviolet Index (UVI). Erythemal irradiance (Eer ) data of such days were analyzed to evaluate this claim. Measurements from 9 stations of the German solar UV monitoring network from 2007 to 2016 yielded 14,431 daily Eer time series of low UVI days. Erythemal doses for certain fixed time intervals-acquired from measurements on horizontal planes-were compared with the average minimal erythemal dose (MED) of skin phototype II. Doses from days with rounded UVI values of 0 were insufficient to induce erythema and even on days with rounded UVI values of 1 doses exceeding 1 MED of skin type II could only be acquired under very specific circumstances of prolonged exposure. Conversely, sun exposure on days with rounded UVI values of 2 can indeed provide doses sufficient to induce erythema in skin type II after two hours around noon. In conclusion, our analyses do not support the claim of harmlessness currently associated with the entire low UVI exposure category in public guidance on interpretation of the UVI.

Estimates of UV Indices During the Periods of Reduced Ozone Content over Siberia in Winter–Spring 2016

UV radiation is calculated for Russian regions where anomalies of the total ozone content were observed in the first quarter of 2016. Winter ozone depletion in northern regions of Siberia, even to the levels of the so-called ozone hole, is not critical. However, much weaker ozone reduction in the early spring can lead to dangerous levels of erythemal UV radiation, when skin protection from ultraviolet radiation is required.

Surface erythemal UV irradiance in the continental United States derived from ground-based and OMI observations: quality assessment, trend analysis and sampling issues

Abstract. Surface full-sky erythemal dose rate (EDR) from the Ozone Monitoring Instrument (OMI) at both satellite overpass time and local noon time is evaluated against ground measurements at 31 sites from the US Department of Agriculture's (USDA) UV-B Monitoring and Research Program (UVMRP) over the period of 2005–2017. We find that both OMI overpass and solar noon time EDR are highly correlated with the measured counterparts (with a linear correlation coefficient of 0.90 and 0.88, respectively). Although the comparison statistics are improved with a longer time window (0.5–1.0 h) for pairing surface and OMI measurements, both OMI overpass and local noon time EDRs have 7 % overestimation that is larger than 6 % uncertainty in the ground measurements and show different levels of dependence on solar zenith angle (SZA) and to lesser extent on cloud optical depth. The ratio of EDR between local noon and OMI overpass time is often (95 % in frequency) larger than 1 with a mean of 1.18 in the OMI product; in contrast, the same ratio from surface observation is normally distributed with 22 % of the times less than 1 and a mean of 1.38. This contrast in part reflects the deficiency in the OMI surface UV algorithm that assumes constant atmospheric conditions between overpass and noon time. The probability density functions (PDFs) for both OMI and ground measurements of noontime EDR are in statistically significant agreement, showing dual peaks at ∼20 and ∼200 mW m−2, respectively; the latter is lower than 220 mW m−2, the value at which the PDF of daily EDR from ground measurements peaks, and this difference indicates that the largest EDR value for a given day may not often occur at local noon. Lastly, statistically significant positive trends of EDR are found in the northeastern US in OMI data, but opposite trends are found within ground-based data (regardless of sampling for either noontime or daily averages). While positive trends are consistently found between OMI and surface data for EDR over the southern Great Plains (Texas and Oklahoma), their values are within the uncertainty of ground measurements. Overall, no scientifically sound trends can be found among OMI data for aerosol total and absorbing optical depth, cloud optical depth and total ozone to explain coherently the surface UV trends revealed either by OMI or ground-based estimates; these data also cannot reconcile trend differences between the two estimates (of EDR from OMI and surface observations). Future geostationary satellites with better spatiotemporal resolution data should help overcome spatiotemporal sampling issues inherent in OMI data products and therefore improve the estimates of surface UV flux and EDR from space.

Development of a UV Index Sensor-Based Portable Measurement Device with the EUVB Ratio of Natural Light.

Ultraviolet (UV) rays are electromagnetic waves that account for about 5% of solar light, and when overexposed, they pose malevolent effects on human skin and health. However, with recent reports on the beneficial effects of some wavelength bands of UV rays, people’s interest in UV information has increased. This has resulted in requiring not just simple information, such as the amount of UV or UV index (UVI), but detailed UV information that directly affects health, such as EUVB (erythemally weighted UVB). However, calculating EUVB, which can be done by applying the erythemal weighted function on the intensity value in wavelength, requires specialized optical measurement devices, which cannot be easily accessed by the general public; furthermore, public institutions’ UV information services do not offer EUVB information for individuals. Therefore, the present study proposes a UVI sensor-based portable measurement device, with which the general public can have easy access to UV-related information. The proposed device comprises a UVI sensor that can measure the intensity of erythemal UV radiation, a Bluetooth Low Energy (BLE) module that supports communication, and a micro controller unit (MCU) for key operations. In addition, it applies the ratio of EUVB by month/time, resulting from the actual analysis of natural light to calculate the EUVB and provides the amount of UVI and EUVB to check if they meet conditions required for outdoor activities through the device and smartphone applications. The applicability of the proposed device was verified by the measurement performance comparison test with the standard device, a spectrometer (CAS 140 CT), which showed an average error of 0.045 for UVI and 0.0014 W/m2. The proposed device’s offering of UV-related information such as UVI and EUVB to the user is expected to prevent potential damage due to exposure to UV and to support healthy outdoor activities.

Daily Maximum Erythemal Dose Rates in the Tropics.

The maximum erythemal dose rate (EDRmax ) at the Earth's surface tends to occur at local noon. However, clouds can make the timing of EDRmax significantly away from local noon. In fact, EDRmax and its time of occurrence depend mainly on the solar zenith angle at noon (SZAn ), site's altitude, the total ozone column (TOC), cloud cover, cloud genera and aerosols. This work depicts the daily incidence of EDRmax for Belo Horizonte (19.92°S, 43.94°W, 858 m a.s.l.) in the Southern Hemisphere tropics for a period of five years (2005-2010). Daily values of EDRmax ranged from 0.063 W m-2 (1σ > 6.9%, Moderate UV-Index of 3, winter) to 0.486 W m-2 (Extreme UVI of 19, summer). Indicative values of EDRmax for cloudless days were 0.336 W m-2 (summer, TOC = 258 Dobson Units), 0.311 W m-2 (fall, 260 DU), 0.253 W m-2 (spring, 274 DU) and 0.143 W m-2 (winter, 246 DU). Radiation enhancement events by clouds made EDRmax up to 45% higher than the reference EDRmax for cloudless summer skies at a time resolution of a few minutes. The main cloud genera to be associated with such events are Cumulus, Altocumulus, Altostratus and Stratocumulus. The EDR can also be significantly affected by aerosols, which attenuated on average 0.031 W m-2 (22%) of the erythemal UV in a case study at the site.

Erythemal UV Dose Rate Spatial Distribution using Ozone Monitoring Instrument Satellite Data over Egypt

The spatial distribution of Erythemal Ultraviolet Dose Rate (EUV) at noon in mW/m2 observations gotten from the Ozone Monitoring Instrument (OMI) are presented over Egypt covering the geographical domain (22.5°–31.5°N, 25.5°–35.5°E) during twelve year from 2005 to 2016. With the end goal of mapping contour, with a spatial resolution of 1°×1° the results illustrated by monthly, seasonally and all period contour maps indicate high similarity of EUV in all years. Monthly correlation (R2) relationship between EUV and Latitude also estimated in simple linear form. High R2 was found in December and January (97%) were low one was found in July (53%). In the frame of the variability, Egypt was considered as an average area; the box-whisker plots were created for average monthly and annual values of EUV. The monthly mean of EUV values are lower in the winter months (December to February) 116.17±2.30 mW/m2 compared to those in the summer months (June to August) 282.36±2.87 mW/m2. The annual mean of EUV values are lower in 2015 (204.15±60.41 mW/m2) and higher in 2013 (213.13±60.34 mW/m2).

Erythemal UV Dose Rate Spatial Distribution using Ozone Monitoring Instrument Satellite Data over Egypt

The spatial distribution of Erythemal Ultraviolet Dose Rate (EUV) at noon in mW/m2 observations gotten from the Ozone Monitoring Instrument (OMI) are presented over Egypt covering the geographical domain (22.5°–31.5°N, 25.5°–35.5°E) during twelve year from 2005 to 2016. With the end goal of mapping contour, with a spatial resolution of 1°×1° the results illustrated by monthly, seasonally and all period contour maps indicate high similarity of EUV in all years. Monthly correlation (R2) relationship between EUV and Latitude also estimated in simple linear form. High R2 was found in December and January (97%) were low one was found in July (53%). In the frame of the variability, Egypt was considered as an average area; the box-whisker plots were created for average monthly and annual values of EUV. The monthly mean of EUV values are lower in the winter months (December to February) 116.17±2.30 mW/m2 compared to those in the summer months (June to August) 282.36±2.87 mW/m2. The annual mean of EUV values are lower in 2015 (204.15±60.41 mW/m2) and higher in 2013 (213.13±60.34 mW/m2).

Relationship between erythemal UV and broadband solar irradiation at high altitude in Northwestern Argentina

An analysis of the broadband solar irradiation, IT, and the erythemal UV irradiation, IUVER, has been performed using the measurements made from 2013 to 2015 at three sites located at altitudes over 1000 m a.s.l. In Northwestern Argentina (Salta, El Rosal, and Tolar Grande). The main objective of this paper is to determine a relationship between IT and IUVER, which would allow to estimate IUVER from IT in places with few IUVER measurements available, and especially in those where is important to establish adequate photoprotection measures given their dense population and location at high altitude. The relationship between the daily values of IUVER and IT has been fitted to a linear regression (IUVER = m IT + n), showing good correlation in the three measurement sites (R2 ≥ 0.77). Besides, the IUVER/IT ratio shows an increase with altitude of 0.32 ± 0.03 units per km, indicating a more significant influence of altitude on IUVER than on IT. Total ozone column also attenuates more IUVER than IT. In order to reduce the local nature of the relationship between IUVER and IT, the clearness indices kT and kTUVER have been used to obtain a multivariable linear regression of kTUVER as a function of the solar zenith angle, θz, and kT, which shows good correlation (R2 ≥ 0.89) for the three measurement sites.

Long‐term erythemal ultraviolet radiation in Novi Sad (Serbia) reconstructed by neural network modelling

In this article, we proposed a simple neural network (NN) technique for estimating erythemal ultraviolet (UV) radiation in Novi Sad (Serbia) using available input parameters. The technique implies the use of one of two models depending on the availability of the input parameter: (a) NN model 1 (NNM1) which uses global solar radiation, clearness index, cloudiness and air mass; and (b) NN model 2 (NNM2) which adds total ozone content (TOC) to the NNM1 inputs. The three feed‐forward NNs with different internal structures and back propagation learning method for each NN model were used in modelling. The parallel calculation was used for learning each NN. The results showed that the NNM1 provides satisfactory estimate (R = 0.975, MBE = −0.614%, MAPE = 12.580%, RMSE = 17.716%) and that additional use of TOC NNM2 considerably improves the results (R = 0.982, MBE = −0.726%, MAPE = 10.161%, RMSE = 14.509%). The performances of developed NNMs become significantly better if warm part of the year is isolated (MAPE = 10.981 and 8.958; RMSE = 13.889 and 11.709, for NNM1 and NNM2, respectively). Variations of reconstructed annual averages of daily doses in the period 1949–2012 indicate ability of the technique to model the relationship between erythemal UV radiation and the affecting atmospheric factors. The analysis showed that the increasing trend during the warm part of the year in the period 1981–1996 was mainly caused by TOC, while the increase after 1996 was to a greater extent caused by cloudiness.

Long-Term Variability of UV Irradiance in the Moscow Region according to Measurement and Modeling Data

We have found distinct long-period changes in erythemal UV radiation (Qer) characterized by a pronounced decrease at the end of the 1970s and a statistically significant positive trend of more than 5%/10 years since 1979 over the territory of the Moscow region according to the measurements and reconstruction model. The positive Qer trend is shown to be associated mainly with a decrease in the effective cloud amount and total ozone content (TOC). Due to these variations, UV resources have significantly changed in spring for the population with the most vulnerable skin type I, which means a transition from the UV optimum to UV moderate excess conditions. The simulation experiments using the INM-RSHU chemistry climate model (CCM) for several scenarios with and without anthropogenic factors have revealed that the variations in the anthropogenic emissions of halogens have the most significant impact on the variability of TOC and Qer. Among natural factors, noticeable effects are observed due to volcanic aerosol. The calculations of the cloud transmittance of Qer are generally consistent with the measurements; however, they do not reproduce the observed value of the positive trend.