The Solar Ultraviolet

Goldberg, Bernard

doi:10.1007/978-1-4613-2227-6_6

Cited by 5 publications

(4 citation statements)

References 11 publications

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“…Time series for three weathering factors~total UV radiation dosage^ [Goldberg, 1986;Berger, 1987;Correll et al, 1992;Kerr and McElroy, 1993], temperature [Labrijn, 1945;Mitchell, 1963;Oliver, 1976;Wallen, 1984;Gibbs and Martin, 1989;Hileman, 1992], and precipitation [Kincer, 1946] -are displayed in figures 8, 9, and 10, respectively. Time series for other weathering factors (e.g., time-ofwetness [Grossman, 1978;Sereda et al, 1982;andMannsfeld, 1982, 1988], atmospheric halocarbons [Hileman, 1992], and acid deposition species (e.g., NOx, SOx, NHi^, Ca^, and H^) [Bilonick, and Nichols, 1983;Correll et al, 1984;Likens et al, 1984;Correll, et al, 1987;Studt, 1991;Jordan et al, 1992] have been published but, the lengths of these time series are too short to establish if there are any trends in the data.…”

Section: Underlying Premisesmentioning

confidence: 99%

Methodologies for predicting the service lives of coating systems

Martin¹

1994

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EXECUTIVE SUMMARYOver the last two decades, the organic coatings industry has undergone rapid technological and structural changes. These changes have been induced by legislative actions such as restrictions pertaining to hazardous chemicals, toxic effluents, and volatile organic compounds. The consequence of these changes has been the displacement of almost all commercially-important, well-established coatings (largely highsolvent coatings) by newer systems, the formulation and application of which arc based on different chemistries and technologies. Unlike the displaced coatings, however, the new coatings do not have performance histories and the only accepted method for generating performance data is through an extensive outdoor exposure program. Since outdoor exposure results typically take five years to obtain, a desperate need exists for a methodology which is capable of generating timely, accurate, and reliable service life estimates of a coating system. This report reviews the attributes of the service life prediction problem which are common to all materials, components, and systems in an effort to establish a set of criteria for assessing the adequacy of existing or proposed service life prediction methodology for coating systems. The current durability methodology and the reliability-based methodology are then evaluated against these criteria.The proposed cnteria include the ability to 1) handle high variability in the time-to-failure data for nominally identical coated panels exposed in the same service environment, 2) analyze multivariate and censored time-to-failure data, 3) establish a connection between laboratory and field exposure results, and 4) quantitatively predict the service life of a coating system exposed in its intended service environment.The current durability methodology was developed prior to the recognition of the proposed criteria and, as such, was not designed to satisfy these criteria. Efforts to correct its deficiencies have been made over the last 80 years, but success has been elusive. The failure of the current methodology has generally been ascribed to inadequacies in laboratory-based aging tests, specifically, the inability to simulate weathering conditions in the laboratory. However, we suggest that the failure of the current methodology can be attributed to its being based on faulty premises, inadequacies in experimental design, and the lack of reproducibility of the weather over any time scale.An alternative, reliability-based methodology is reviewed and assessed. This methodology has a strong theoretical basis plus a history of successful applications in the electronics, medical, aeronautical, and nuclear industries. A number of experiments with coatings has already been conducted using this methodology. The results indicate that this methodology can be applied in predicting the service life of coating systems and that it satisfies the proposed service life prediction criteria. Implementation of a reliability-based methodology will require substantial changes in the cu...

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Section: Underlying Premisesmentioning

confidence: 99%

Methodologies for predicting the service lives of coating systems

Martin¹

1994

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“…At 60"N latitude in July, the BEIlMs dropped to 1.8 x lo-' W/ m2, increasing the required exposure time for 50% immune suppression to about 39 min. To compare these values to BEIiMs based on actual measurements of natural sunlight, we convoluted the action spectrum for immune suppression with a groundbased measurement of noontime solar UVB at 39"N latitude in July (Goldberg, 1986).…”

Section: Biologically Effective Irradiance For Immune Suppression Fromentioning

confidence: 99%

Biologically Effective Doses of Sunlight for Immune Suppression at Various Latitudes and Their Relationship to Changes in Stratospheric Ozone

Fabo

Noonan

Frederick

1990

Photochem & Photobiology

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Using information on solar irradiance at different latitudes derived from a radiative transfer model and a detailed in vivo action spectrum for immune suppression in a murine system, we report here calculations of the "biologically effective" irradiance of sunlight for immune suppression. From 40 degrees N to 40 degrees S in summer, under normal stratospheric ozone concentrations this value ranged from 0.27 W/m2 (40 degrees N or S) to a peak of 0.33 W/m2 (20 degrees N or S) predicting that 50% immune suppression in the Balb/c mouse would occur after 21-26 min of sunlight exposure within this latitude range. We also found that the most effective wavelengths for immune suppression shift from a peak of 270 nm in the laboratory to near 315 nm in sunlight. Furthermore, using ozone depletion scenarios of 5 to 20%, at latitudes 20 degrees S and 40 degrees N, a 0.6% increase in biologically effective irradiance levels of solar UVB for immune suppression was predicted for each 1% decrease of ozone. This value rose to a nearly 1% increase for each 1% decrease in ozone at 60 degrees N latitude in wintertime. These data indicate that activation of immune suppression, in a murine model, requires relatively low levels of sunlight and that these levels are easily obtainable over most of the populated regions of the world. Since a UVB-activated photoreceptor, urocanic acid, regulates immune suppression in mice and since this same compound exists on other mammalian skin, including human skin, suppression of the mammalian immune system is predicted to increase if substantial stratospheric ozone depletion takes place.

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“…The observations were collected with high precision scanning radiometers (Goldberg, 1982(Goldberg, , 1986). The data recw n:ta The convolution of the erythema1 action spectrum and UV-B irradiances is performed by a discrete-valued numerical integration illustrated in Table 1.…”

Section: Methodsmentioning

confidence: 99%

“…Mean Sun Protection Factor (SPF) of the atmosphere (solid line, right scale) and the mean normalized transmissivity (dashed line, left scale) against solar zenith angle in degrees (bottom scale) for 28 clear summer days in1984, 1986and 1988 …”

mentioning

confidence: 99%

Atmospheric Sun Protection Factor on Clear Days: Its Observed Dependence on Solar Zenith Angle and Its Relevance to the Shadow Rule for Sun Protection

Holloway¹

1992

Photochem & Photobiology

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Abstract-Global irradiances measured in seven 5-nm bands of UV-B at Rockville, MD (39. l0N, 77.1"W) on 28 clear days near the summer solstice are convoluted with the erythemal action spectrum of human skin to determine dose rates at various hours of the day. These rates are averaged with respect to solar zenith angle to obtain the diurnal variation of mean dose rate and of the Sun Protection Factor (SPF) of the atmosphere (reciprocal of the normalized atmospheric transmissivity) on a typical clear summer day in Rockville. At a 45" zenith angle the atmospheric SPF is computed to be 2.7 and increases rapidly to greater than 7 at 60".Dose rates are integrated with respect to time to obtain estimates of mean doses for various periods during clear days at Rockville in mid summer and near the autumnal equinox. In mid summer the effective erythemal UV-B exposure during the period when the solar zenith angle is less than 45" is about five times greater than that during the remainder of the day. These observations provide scientific basis for a shadow rule for solar UV-B protection: when shadows are shorter than objects casting them, sunburn is much more likely than at other times.

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The Solar Ultraviolet

Cited by 5 publications

References 11 publications

Methodologies for predicting the service lives of coating systems

Methodologies for predicting the service lives of coating systems

Biologically Effective Doses of Sunlight for Immune Suppression at Various Latitudes and Their Relationship to Changes in Stratospheric Ozone

Atmospheric Sun Protection Factor on Clear Days: Its Observed Dependence on Solar Zenith Angle and Its Relevance to the Shadow Rule for Sun Protection

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