Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1992-9-14
pubmed:abstractText
Global irradiances measured in seven 5-nm bands of UV-B at Rockville, MD (39.1 degrees N, 77.1 degrees 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 degrees zenith angle the atmospheric SPF is computed to be 2.7 and increases rapidly to greater than 7 at 60 degrees. 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 degrees 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.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0031-8655
pubmed:author
pubmed:issnType
Print
pubmed:volume
56
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
229-34
pubmed:dateRevised
2004-11-17
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Atmospheric sun protection factor on clear days: its observed dependence on solar zenith angle and its relevance to the shadow rule for sun protection.
pubmed:affiliation
Geophysical Fluid Dynamics Laboratory/NOAA, Princetown, NJ 08542.
pubmed:publicationType
Journal Article