Shadow method for sun protection

Holloway, Leith

doi:10.1016/0140-6736(90)90725-k

Cited by 5 publications

(2 citation statements)

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“…The value of 2.7 in Table 3 for the mean normalized SPF at a zenith angle of 45 degrees is good justification for the rule of thumb for sun protection that the author proposed in a popular science article (Holloway, 1987) and in The Lancet (Holloway, 1990): "When your shadow is shorter than you are tall, the sun is much more likely to bum you than at other times." Shadows on a horizontal surface outdoors in the sun are shorter than the objects casting them when the solar zenith angle is less than 45 degrees.…”

Section: Resultsmentioning

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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Section: Resultsmentioning

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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“…The shadow rule from the period before the UVI was instituted suggests more than 45° of sun elevation as an indication for the application of protective measures. The rule is based on UV radiation measurements, but total ozone column values were not considered (8–10).…”

Section: Introductionmentioning

confidence: 99%

Indicator of UV Index Intervals

Letić¹

2009

Photochem & Photobiology

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A simple device for indication of intervals of UV index (UVI) values and the level of necessary protection is constructed. The indication is based on the solar elevation angle and total ozone column values. The recommended level of protection is indicated via color-coded (red, yellow, green) intervals on the scale of the device. Comparisons of the indication of the device to the forecast of UVI for 165 days during spring, summer and fall for Belgrade, Serbia showed that for 162 days the indication about application of protective measures was in agreement with the UVI forecast. The indicator is simple, easy to use, straightforward and reliable in determining the interval of UVI values and the level of necessary protection from UV radiation.

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Shadow rule for sun protection

Holloway¹

1994

Journal of the American Academy of Dermatology

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Shadow method for sun protection

Cited by 5 publications

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

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

Indicator of UV Index Intervals

Shadow rule for sun protection

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