Doses Of Solar Ultraviolet Radiation Research Articles

ANÁLISIS DE LA IRRADIANCIA SOLAR UV PARA LA SÍNTESIS DE PRE-VITAMINAD3EN LA PIEL, EN ROSARIO, ARGENTINA

In the last years, the study of vitamin D has raised due to the increase in the incidence of people who have deficientlevels of this vitamin. Few foods contain vitamina D3naturally, the main source of obtaining the ultraviolet (UV)solar radiation, which triggers the synthesis on the skin’s surface. In this study, the effective UV solar irradiance forthe synthesis of pre-vitamin D3was determined in Rosario city, Argentina, using three methods: a) ProportionalityCoefficient, b) Herman’s equation and c) TUV model. The values were compared in clear sky conditions at solar noon.The Solar Exposure Times (TES) that reach the minimum doses of solar UV radiation for the synthesis of pre-vitaminD3and erythema were calculated, along the period june 2019 - may 2020. The variation of the TES to accumulate theminimum dose of pre-vitamin D3and erythema with a photoexposure of 25 % of the body (face, neck and arms) isdiscussed.

Wearable Bracelet Monitoring the Solar Ultraviolet Radiation for Skin Health Based on Hybrid IPN Hydrogels

The risk of extensive exposure of the human epidermis to solar ultraviolet radiation is significantly increased nowadays. It not only induces skin aging and solar erythema but also increases the possibility of skin cancer. Therefore, a simply prepared, highly sensitive, and optically readable device for monitoring the solar ultraviolet radiation is highly desired for the skin health management. Because of the photoinitiated polymerization triggered by graphene-carbon nitride (g-C3N4) under ultraviolet radiation, g-C3N4 is homogeneously distributed in the hybrid hydrogels containing N-isopropylacrymide (NIPAM), poly(ethylene glycol) methyl ether methacrylate (OEGMA300), and sodium alginate (SA). By further immersing the hybrid hydrogels into calcium chloride solution, hybrid alginate-Ca2+/P(NIPAM-co-OEGMA300)/g-C3N4 interpenetrating polymeric network (IPN) hydrogels are obtained. Due to the homogeneous distribution of g-C3N4 and the existence of thermoresponsive polymers, the hybrid IPN hydrogels present good adsorption capability and high degradation efficiency for methylene blue (MB) especially at high temperature under ultraviolet radiation. Based on this unique property, the bracelet monitoring skin health is prepared by simply immersing the hybrid IPN hydrogels into the MB solution and then wrapping it with PET foil. Because the immersion time for the top, middle, and bottom parts of the hybrid IPN hydrogels is gradually increased, their colors vary from light to dark blue. A longer time is required for the discoloration of the darker part under solar ultraviolet radiation. Thus, the bracelet can be used to conveniently monitor the dose of solar ultraviolet radiation by simply checking the discoloration in the bracelet under sunshine. Due to the facile preparation and low cost of the bracelet, it is a promising candidate for wearable devices for skin health management.

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%.

Variations and trends of biologically effective doses of solar ultraviolet radiation in Asia, Europe and South America from 1999 to 2007

Biological monitoring of solar UV radiation using spore dosimeters has been undertaken since the year 1999 at more than 20 sites in Asia, Europe and South America. The monthly-cumulative data to the end of the year 2004 have been presented before. In this paper, successive data to the end of the year 2007 are compiled and the trends and correlation analyses with yearly and monthly average amounts of columnar ozone are presented. Mean yearly doses at 10 northern and 6 southern hemisphere sites exhibited exponential latitudinal gradients with similar slopes indicating a doubling of the dose with the decline of about 14 degrees. Among 12 sites where continual data for more than 6 years were available, increasing trends in yearly UV doses were observed at 11 sites. At one European (Brussels), two tropical Asian (Padang and Denpasar), and two South American (São Martinho and Punta Arenas) sites, decreasing trends of ozone amounts were noted, whereas at the remaining 6 sites (five sites in Japan and Thessaloniki), increasing trends of the UV doses were observed without notable changes, or with an increase at one site (Kiyotake), of the average ozone amounts. At one site (Taipei), the UV doses and the ozone amounts stayed constant. In the monsoon areas, climatic variations and changes, particularly in the extent of cloudiness and frequency of rainfall in summer months, might have been largely responsible for the trends of the UV doses. However, even at these sites, the decreases in the ozone amounts in summer months were frequently observed and might have contributed to the increasing trends of the UV doses. Since each region and locality is unique in climatic and atmospheric conditions, it is not easy to generalize the global trends. However, at many sites involved in this monitoring project, the increases in the biological UV doses during this period seemed to be linked to the decreases in the ozone amounts.

Effect of solar UV radiation on earthworm ( Metaphire posthuma)

Human health risks like damage to the eyes, immune system, and skin are known to be associated with increasing ultraviolet radiation (UVR) in the environment. In this study, we evaluated the phototoxic effects of UVR in sunlight and its possible mechanism of action by using earthworm as an alternative model because earthworm skin contains several biomolecules (tetraene and triene sterol) similar to human beings. We studied the generation of reactive oxygen species (ROS), photooxidation of lipids, and histopathological changes in earthworm integument. It was observed that UVR-exposed earthworm skin homogenate produced a significant amount of singlet oxygen ( 1O 2), superoxide anion (O 2 − ), hydroxyl radicals ( OH), and photooxidation of lipids. The production of ROS and lipid peroxidation product was found dependent on the dose of solar UVR in earthworm integument. Histological anomalies such as thickening, vacuolation, and hypertrophy of epidermal cells were observed when the animals were exposed for 1 to 2 h, while a higher exposure period (3 h) caused degeneration of circular and longitudinal muscles. Continuous sunlight exposure for more than 3 h was found lethal to worms. These observations suggested that the current level of UVR in sunlight may produce significant phototoxic effects in the earthworms probably via the generation of ROS (photodynamic action). Possible increases in UVR in view of ozone depletion may be more detrimental to the biomolecules in the worm's skin. The earthworm thus turned out as a simple, sensitive, and cost-effective test organism for the assessment of the hazardous potential of solar radiation and also for planning safety measures for human beings.

Contact lens dosimetry of solar ultraviolet radiation

Background: Ultraviolet radiation from the sun has been implicated in the pathogenesis of many ocular conditions. However, the amount of UV reaching the eye is not well defined. Methods: A contact lens made from the UV‐sensitive plastic polysulphone was used to measure the dose of UV radiation at the surface of the eye for two subjects over six wearing trials. Results: The average ratio of UV radiation exposure at the surface of the eye to that of the UV radiation in the surrounding environment (ambient dose) was found to be 28 ± 9 per cent. The temporal UV dose appeared lower than both the central and nasal UV doses in five of the six wearing trials but these differences did not reach statistical significance. Conclusions: Contact lenses made from polysulphone can be used to estimate the regional dose of solar ultraviolet radiation. (Clin Exp Optom 1997; 80: 6: 204–210)

Factors affecting solar UV radiation changes: a study of the new Robertson-Berger meter (UV-biometer model 501A) and Brewer data records taken at Belsk, Poland, 1993–1994

Abstract Daily doses of the erythemal solar ultra violet radiation (SUVR) reaching the ground at Belsk, Poland (52 °N, 21 °E) measured by a Brewer spectrophotometer and a UV-biometer model 501A during 1993–1994 in conjunction with daily total ozone and integrated global solar radiation observations are examined to infer their associations under all sky conditions. The observed doses are normalized using the SUVR daily doses obtained from a parametric model (a modified Bird and Riordan (1986) model). The daily variations of the normalized SUVR doses by the Brewer spectrophotometer and UV-biometer appear to be in harmony (the correlation coefficient is 0.99). A regression model is fitted to the normalized erythemal SUVR to delineate the impact of total ozone and clouds/aerosols on the SUVR. The model explains about 95% of the variance in the normalized SUVR doses and it may constitute an efficient diagnostic model for day-to-day variations of daily doses of the erythemal SUVR. It is found that the ratio of the daily value of integrated global solar radiation measured on a horizontal surface to its clear sky representative (from the Bird and Riordan (1986) model) can be used as a characteristic of the surface SUVR changes induced by atmospheric transparency changes (caused by clouds and aerosols). In view of the model's results it seems possible that daily doses of the erythemal SUVR at ground level are less sensitive to the ozone changes during overcast days than those during cloudless days; participation of the SUVR in the integrated global solar radiation is almost the same during clear-sky and overcast days.

A mathematical model of the biologically effective dose of solar UVA received by patients undergoing oral psoralen photochemotherapy for psoriasis

A theoretical analysis is presented of the biologically effective dose of the solar long wave ultraviolet radiation (UVA) received by patients who are being treated for psoriasis by oral psoralen photochemotherapy. It is shown that patients treated during the summer months in the UK may well receive a UV dose which is comparable with, or even in excess of, the dose of artificial UVA received in the treatment centre and consequently should be advised about limiting their exposure to sunlight on the treatment days. In the winter months in the UK the UVA intensity in sunlight is such that no unduly restrictive precaution need apply. However, at locations between about 40 degrees N and 40 degrees S, the solar UVA intensity in midwinter is still sufficiently high that unnecessary sunlight exposure on treatment days should be avoided.