Erythemal Ultraviolet Radiation Research Articles

Diffuse component of solar ultraviolet radiation in tree shade

The first set of quantitative data of diffuse erythemal UV and UV-A radiation in tree shade at a sub-tropical Southern Hemisphere latitude is presented. Over the summer, approximately 60% of the erythemal UV radiation in tree shade is due to the diffuse component. Similarly, approximately 56% of the UV-A radiation in tree shade is due to the diffuse component. In tree shade these diffuse UV percentages are relatively constant from the morning to noon to afternoon periods. In comparison, in full sun, there is a decrease in the percentage of diffuse UV from morning to noon to afternoon. The exposures to diffuse UV on a horizontal plane in tree shade between 9:00 EST and 15:00 EST are of the order of 4 MED (minimum erythemal dose)and 14 J cm −2 for erythemal UV and UV-A, respectively. The high diffuse UV component in the shade may result in high UV exposures not only to unprotected parts of the body on a horizontal plane, but also in equally high UV irradiances to parts of the body, including the eyes and face, that are not UV protected.

Validation of an UV inversion algorithm using satellite and surface measurements

Ultraviolet radiation in the spectral region between 280 and 315 nm (often referred to as UV‐B) is harmful to living organisms. Satellite‐based estimation of surface UV‐B supplements the sparsely distributed ground‐based UV‐B monitoring networks. This study is concerned with validation of an inversion algorithm [Li et al., this issue] for retrieving spectrally integrated UV‐B (no spectral weighting) and erythemal UV (EUV) (with spectral weighting) fluxes at the surface from satellite. The physical inversion algorithm contains a few analytical expressions and input parameters: the solar zenith angle, ozone amount, albedo at the top of the atmosphere (TOA), and aerosol variables. The algorithm is applied to satellite measurements of total ozone amount and 360 nm reflectance from Meteor 3/TOMS and visible reflectance from NOAA/AVHRR. The retrieved UV‐B and EUV fluxes are compared with ground UV observations made at six Canadian UV observation stations with Brewer instruments from 1992 to 1994. Under all‐sky conditions the comparisons showed very small mean differences and relatively large standard deviations (s.d.): 0.033 W/m2 (mean) and 0.287 W/m2 (s.d.) for total UV‐B and 3.02 mW/m2 (mean) and 12.0 mW/m2 (s.d.) for EUV radiation. The large standard deviations are attributed to the inhomogeneity in sky condition and mobility of cloudy scenes, which renders an inaccurate match between satellite and surface measurements. The comparisons under clear‐sky conditions showed very small mean and standard differences. By means of a running average over a period of time, satellite inversion can track the variation of surface‐observed UV‐B and EUV very well.

Personal exposure distribution of solar erythemal ultraviolet radiation in tree shade over summer

The personal radiant exposure distribution of solar erythemal UV in tree shade for an upright posture was measured, with measurements over the whole summer for a total of 17 trees. For each tree, the personal radiant exposure distribution was measured for both the morning and afternoon periods. The exposure ratios averaged over all the trees and over the morning and afternoon periods ranged from 0.16 to 0.49 for the different anatomical sites. A numerical model was employed to estimate the UV radiant exposure to humans in tree shade over the entire summer. The body sites with the higher exposure ratios in the tree shade were the vertex of the head, shoulders and forearms with radiant exposures over the summer of 1300 MED to the vertex of the head and 1100 MED to the shoulders and forearms. These radiant exposures in the shade are substantially higher than the ambient erythemal UV measured in full sun on a horizontal plane over a full summer at a more temperate northern hemisphere latitude. The average radiant exposures per day to each anatomical site for a complete day in the tree shade ranged from 4.6 to 14.6 MED. This research has provided new data that is essential to quantify human UV exposure during outdoor activities.

Ultraviolet radiation and health effects in the Antarctic

With the recognition that global climate change may adversely affect human health, there has been an increase in relevant research worldwide. In the Antarctic medical research has been largely directed at the potential health effects of stratospheric ozone depletion. For over a decade continuous broad-band measurements of ultraviolet radiation (UVR) have been made at all Australian stations. Results of UV measurements are presented and comparisons made with the “ozone hole” moving over the stations, erythemal UVR increasing by a factor of more than 2.5 over a three day period. During late spring and despite the large difference in latitude, Davis, Antarctica, and Melbourne, Australia, are very similar in erythemal UVR. Antarctic immunological and photo biological research is presented and the role of UVR discussed. Epidemiological data is reviewed for short-term links between UVR and related disease. With increased awareness of the dangers of UVR and consequent changes in sun-related behavior, the incidence of the acute effects of UVR is much lower than decades ago. As the itinerant Antarctic population spends a maximum of 12-1 8 months at a time in that location it is an excellent control group for studies on the health effects of UVR on permanent populations at similar latitudes in the Arctic.

Field Measurements on Protection by Stockings from Solar Erythemal Ultraviolet Radiation

The ultraviolet (UV) radiation protection provided by stockings was measured by simulating as closely as possible the real life situation under field conditions in Queensland, Australia. Polysulphone dosemeters were employed for measuring the solar erythemal UV radiation to sites on the leg with a polysulphone dosemeter located both above and underneath the stockings to compare the protected and unprotected erythemal UV exposures. The solar ultraviolet protection factor (UPF) was measured for different stocking thicknesses or denier and for different colours. Under the field conditions, the highest UPF of 4.6 was provided by the 50 denier stockings with the lowest of 1.4 to 1.8 for the 15 denier. For the 15 denier stockings, there was no significant difference between the lighter colours with only a small increase in UPF to 1.8 for the darker colour. People who require photoprotection to the legs should wear trousers or at least the 50 denier stockings. Considerations of comfort are not taken into account in this study.

Surface UV radiation over Australia, 1979–1992: Effects of ozone and cloud cover changes on variations of UV radiation

Time series of daily erythemal ultraviolet radiation (UVR) exposure, ozone, and cloud cover were analyzed over the Australian continent using data sets from the NASA Total Ozone Mapping Spectrometer (TOMS) from 1979–1992. The TOMS UVR exposures showed good agreement with data from surface observations. Using a relationship derived from comparisons of the TOMS partial cloud reflectivities with surface cloud cover observations, the TOMS reflectivities were converted into estimates of cloud cover for several Australian regions. It was shown that the deseasonalized time series of UVR exposures can be statistically described as a linear function of ozone and cloud cover anomalies. Results of a trend analysis indicated statistically significant increases in UVR exposures of 10% decade−1 in the summer months in the tropics. These were associated with a simultaneous depletion of ozone and a decrease in cloud cover. Midlatitudinal regions showed no significant trends of UVR. It was found that variations of ozone and UVR over Australia were significantly influenced by the quasi‐biennial oscillation (QBO). An increase in zonal wind strength of 20 m s−1 was correlative with reductions of ozone of 1.7% and enhancements of UVR exposures of 2.2%. An increase in solar radio flux of 100×10−22 W m−2 (Hz)−1 was associated with significant reductions of UVR of 5–10% in the tropical and subtropical regions in summer. The results suggested that enhancements in summer UVR exposures of about 10–20% above the climatological average might be expected in years in which the QBO is in its westerly phase and the solar cycle is at its minimum.

UV-B radiation at Penang

A new series of measurements including global and UV radiation was initiated in 1994 at Penang. These high quality data were used to study diurnal and seasonal variations. The mean daily total UV-B and global radiation is about 1.43×10 4 J and 1.77×10 7 J, respectively. Maximum radiation values for both the UV-B and global radiation are received in March and September. The daily total global radiation shows a bigger seasonal variation than UV-B radiation. On clear days, the erythemal UV radiation flux is in the high or extreme range for about 5 h beginning at around 1030 hours throughout the year. Penang (5.3°N) and Natal (6°S) are found to exhibit similar daily maximum erythemal UV irradiance values. A simple empirical relationship for the noontime UV-B flux and global irradiance in the equatorial/tropical regions has been established.

Ultraviolet radiation and health effects in the Antarctic

With the recognition that global climate change may adversely affect human health, there has been an increase in relevant research worldwide. In the Antarctic medical research has been largely directed at the potential health effects of stratospheric ozone depletion. For over a decade continuous broad-band measurements of ultraviolet radiation (UVR) have been made at all Australian stations. Results of UV measurements are presented and comparisons made with the “ozone hole” moving over the stations, erythemal UVR increasing by a factor of more than 2.5 over a three day period. During late spring and despite the large difference in latitude, Davis, Antarctica, and Melbourne, Australia, are very similar in erythemal UVR. Antarctic immunological and photo biological research is presented and the role of UVR discussed. Epidemiological data is reviewed for short-term links between UVR and related disease. With increased awareness of the dangers of UVR and consequent changes in sun-related behavior, the incidence of the acute effects of UVR is much lower than decades ago. As the itinerant Antarctic population spends a maximum of 12-1 8 months at a time in that location it is an excellent control group for studies on the health effects of UVR on permanent populations at similar latitudes in the Arctic.

Changes in biologically active ultraviolet radiation reaching the Earth's surface

Stratospheric ozone levels are near their lowest point since measurements began, so current ultraviolet-B (UV-B ) radiation levels are thought to be close to their maximum. Total stratospheric content of ozone-depleting substances is expected to reach a maximum before the year 2000. All other things eing equal, the current ozone losses and related UV-B increases should be close to their maximum. Increases in surface erythemal (sunburning) UV radiation relative to the values in the 1970s are estimated to be: about 7% at Northern Hemisphere mid-latitudes in winter/spring; about 4% at Northern Hemisphere mid-latitudes in summer/fall; about 6% at Southern Hemisphere mid-latitudes on a year-round basis; about 130% in the Antarctic in spring; and about 22% in the Arctic in spring. Reductions in atmospheric ozone are expected to result in higher amounts of UV-B radiation reaching the Earth's surface. The expected correlation between increases in surface UV-B radiation and decreases in overhead ozone has been further demonstrated and quantified by ground-based instruments under a wide range of conditions. Improved measurements of UV-B radiation are now providing better geographical and temporal coverage. Surface UV-B radiation levels are highly variable because of cloud cover, and also because of local effects including pollutants and surface reflections. These factors usually decrease atmospheric transmission and therefore the surface irradiances at UV-B as well as other wavelengths. Occasional cloud-induced increases have also been reported. With a few exceptions, the direct detection of UV-B trends at low- and mid-latitudes remains problematic due to this high natural variability, the relatively small ozone changes, and the practical difficulties of maintaining long-term stability in networks of UV-measuring instruments. Few reliable UV-B radiation measurements are available from pre-ozone-depletion days. Satellite-based observations of atmospheric ozone and clouds are being used, together with models of atmospheric transmission, to provide global coverage and long-term estimates of surface UV-B radiation. Estimates of long-term (1979–1992) trends in zonally averaged UV irradiances that include cloud effects are nearly identical to those for clear-sky estimates, providing evidence that clouds have not influenced the UV-B trends. However, the limitations of satellite-derived UV estimates should be recognized. To assess uncertainties inherent in this approach, additional validations involving comparisons with ground-based observations are required. Direct comparisons of ground-based UV-B radiation measurements between a few mid-latitude sites in the Northern and Southern Hemispheres have shown larger differences than those estimated using satellite data. Ground-based measurements show that summertime erythemal UV irradiances in the Southern Hemisphere exceed those at comparable latitudes of the Northern Hemisphere by up to 40%, whereas corresponding satellite-based estimates yield only 10–15% differences. Atmospheric pollution may be a factor in this discrepancy between ground-based measurements and satellite-derived estimates. UV-B measurements at more sites are required to determine whether the larger observed differences are globally representative. High levels of UV-B radiation continue to be observed in Antarctica during the recurrent spring-time ozone hole. For example, during ozone-hole episodes, measured biologically damaging radiation at Palmer Station, Antarctica (64 °S) has been found to approach and occasionally even exceed maximum summer values at San Diego, CA, USA (32 °N). Long-term predictions of future UV-B levels are difficult and uncertain. Nevertheless, current best estimates suggest that a slow recovery to preozone depletion levels may be expected during the next half-century. Although the maximum ozone depletion, and hence maximum UV-B increase, is likely to occur in the current decade, the ozone layer will continue to be in its most vulnerable state into the next century. The peak depletion and the recovery phase could be delayed by decades because of interactions with other long-term atmospheric changes, e.g., increasing concentrations of greenhouse gases. Other factors that could influence the recovery include non-ratification and/or non-compliance with the Montreal Protocol and its Amendments and Adjustments, and future volcanic eruptions. The recovery phase for surface UV-B irradiances will probably not be detectable until many years after the ozone minimum.

A comparison of cloudless sky erythemal ultraviolet radiation at two sites in southwest Sweden

This case study examines the variability of ultraviolet erythemal radiation at two different but nearby locations in southwest Sweden. Data from two identical radiometers were analysed. One instrument sampled the urbanised environment of Göteborg (latitude: 57.70°N, longitude: 12.00°E), while the second one sampled a rural site, Koster Island (latitude: 58.83°N; longitude: 11.00°E), some 143 km to the north. Both radiometers were intercompared during the field season, and one radiometer had its calibration traced to a WMO/STUK intercomparison performed in 1995. Only cloudless data for the period 1 April 1996–30 September 1996 are examined in this study. Higher depletion was reported at Koster Island for the 4 days which were simultaneously cloudless at both sites. A cloudless model developed by Green et al. (Green, A.E.S., Cross, K.R. and Smith, L.A. 1980.Photochem. Photobiol., 31, 59–65.) was used to determine daily measured/model ratios for both sites. However there is some uncertainty in these ratios due to the spatial variability in total column ozone. Examining seasonal trends, much scatter is reported at both sites, although after day 226 (13 August 1996), distinctly lower ratios were reported at Koster Island. By examining pyranometer and relative humidity data at both sites, it is argued that coastal haze at Koster Island may explain the higher depletion there. © 1998 Royal Meteorological Society

A comparison of cloudless sky erythemal ultraviolet radiation at two sites in southwest Sweden

This case study examines the variability of ultraviolet erythemal radiation at two different but nearby locations in southwest Sweden. Data from two identical radiometers were analysed. One instrument sampled the urbanised environment of Goteborg (latitude: 57.70°N, longitude: 12.00°E), while the second one sampled a rural site, Koster Island (latitude: 58.83°N; longitude: 11.00°E), some 143 km to the north. Both radiometers were intercompared during the field season, and one radiometer had its calibration traced to a WMO/STUK intercomparison performed in 1995. Only cloudless data for the period 1 April 1996–30 September 1996 are examined in this study. Higher depletion was reported at Koster Island for the 4 days which were simultaneously cloudless at both sites. A cloudless model developed by Green et al. (Green, A.E.S., Cross, K.R. and Smith, L.A. 1980.Photochem. Photobiol., 31, 59–65.) was used to determine daily measured/model ratios for both sites. However there is some uncertainty in these ratios due to the spatial variability in total column ozone. Examining seasonal trends, much scatter is reported at both sites, although after day 226 (13 August 1996), distinctly lower ratios were reported at Koster Island. By examining pyranometer and relative humidity data at both sites, it is argued that coastal haze at Koster Island may explain the higher depletion there. © 1998 Royal Meteorological Society

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.

Ultraviolet Radiation-Induced Immune Modulation: Potential Consequences for Infectious, Allergic, and Autoimmune Disease

Ultraviolet Radiation-Induced Immune Modulation: Potential Consequences for Infectious, Allergic, and Autoimmune Disease

Ultraviolet radiation-induced immune modulation: potential consequences for infectious, allergic, and autoimmune disease.

Ultraviolet radiation-induced immune modulation: potential consequences for infectious, allergic, and autoimmune disease.

Measurement of UVA exposure to solar radiation.

Exposure to solar UVA (320-400 nm) radiation can damage DNA and lead to skin disorders. Conventional dosimetry using a single piece of polysulfone or diglycol carbonate (CR-39) cannot provide accurate measurement of the biologically effective irradiance for erythema for the UVA waveband. A package employing four dosimeters (polysulfone, nalidixic acid, 8-methoxypsoralen and phenothiazine) has been shown to be effective for use as a spectrum evaluator for evaluating the UVA source spectrum. In Brisbane, on a horizontal position, the spectrum evaluator requires about 5 min exposure in summer and about 20 min in winter. This amounts to about 10 mJ cm-2 of erythemal UV radiation.

The Angular Distribution of Solar Ultraviolet, Visible and Near‐Infrared Radiation from Cloudless Skies

Abstract— The amount of solar radiation intercepted by an object depends on the orientation of the object with respect to the sun and the angular distribution of the diffuse component of solar radiation, which is commonly considered to be approximately isotropic. The angular distribution of the diffuse UV, visible and near‐infrared insolation was measured at several solar zenith angles between 32° and 68° under cloudless skies at Lauder, New Zealand (45S), and shown to be anisotropic. The diffuse solar UV radiation increases markedly with solar elevation and is a large proportion of the total UV irradiance. The diffuse visible light and infrared radiation are small components of the total irradiance and almost independent of solar elevation. The angular distribution of erythemal UV radiation was tabulated and is available on request.

Unprecedented 1993 ozone decrease over the United States from Dobson spectrophotometer observations

Dobson spectrophotometer observations conducted since the early‐to‐mid 1960s at Bismarck, North Dakota; Caribou, Maine; Boulder, Colorado; Wallops Island, Virginia; Nashville, Tennessee; and at Fresno, California, since 1983, have revealed record low total ozone values during 1993. The tendency toward the low ozone values began in May 1992, but accelerated in early 1993. During January–August 1993, ozone monthly means at the stations were more than 2 standard deviations below long‐term normal monthly means 72% of the time and more than 3 standard deviations below normals 42% of the time. On average, the January–April 1993 ozone values were 12.6% below normal, with ozone deficits as large as 18% observed at Caribou and Wallops Island in January. Of particular concern are unusually low ozone values that occur in summertime when solar ultraviolet insolation is high. Such record lows occurred at four of the six stations (Caribou, Wallops Island, Fresno, and Nashville). During May–August 1993, ozone was on average 8.5% below normal at these sites. Monthly means at these stations were, furthermore, lower on average by 3.7% than corresponding lowest values observed there in the past. The ozone decrease of 12.6% below normal at the six continental Dobson instrument stations during the winter and spring months of 1993 implies a possible average increase in UV erythemal radiation at that time of 16–25% above normal. The 8.5% decrease in ozone at Caribou, Wallops Island, Fresno, and Nashville, implies that on average, UV erythemal radiation may have been higher than normal at these stations during the summer of 1993 by 11–17%.

Erythemal Response of Biologically Denuded Sheep to Sunlight and the Effects on Skin Structure and Wool Growth

Minimal erythema was produced in the skin of three Merino sheep, which had been denuded with cyclophosphamide, with I . I sunburn units of solar erythemal ultraviolet radiation, as measured by a magnesium tungstate detector. The pigmented skin of two Suffolk sheep required 1�7-4�2 sunburn units, depending on the degree of pigmentation. A single dose of 5 sunburn units induced encrustation of the skin 4 days later in both the Merinos and Suffolks.

Consequences of tinting in aircraft windshields.

Optical properties arc determined for samples of widely used light-absorbing windshields of civil aircraft. A literature survey indicates that (1) the light absorption has little effect on visual performance in daylight, but is hazardous in twilight and at night; (2) coloration may adversely affect signal perception in day and night conditions; (3) absorption of erythemal ultraviolet radiation is necessary, and, for near ultraviolet and infrared radiation, absorption is desirable.

The Measurement of Erythemal Ultraviolet Radiation

The Measurement of Erythemal Ultraviolet Radiation