Travel Reference
In-Depth Information
Gradually increasing exposure to sunlight permits natural tanning and thickening of the
skin and helps avoid sunburn, although sunscreens should still be applied. For many red-
heads and some other light-skinned individuals, adequate tanning is impossible.
The sun protection factor (SPF) is a value that indicates how much longer an individual
can tolerate direct sunlight when protected by a sunscreen than with no protection. When
protected by a sunscreen with an SPF of 12, a person whose skin would begin to turn red
afterfiveminutesofunprotectedsunexposurecouldstayinthesunfortwelvetimeslonger
or sixty minutes before the skin would begin to redden.
Clothing is protective against UVB, but the level of protection is dependent upon how
tightly the fabric is woven. If the fabric is held up to a light bulb and images can be seen
through it, the SPF is less than 15. If light gets through but no images, the SPF is 15 to 50.
IfnolightcomesthroughtheSPFisgreaterthan50.Ifthefabriciswet,itdoesnotprovide
as much protection. Clothing made from sun-protective fabric can be purchased from sev-
eral sources. Hats with wide brims (three inches) provide protection of the face and neck.
Baseball-style caps protect only the forehead or, if worn backward, only the back of the
neck.
Protective creams or lotions that contain sunscreens are the typical methods for protect-
ing exposed skin from sunlight. They should be applied liberally and frequently. Most in-
dividualsdonotuseenough—aboutoneounceperdayisrequired—nordotheyapplysun-
screensasoftenasneeded—everyonetotwohours.SPFdeterminationsarebasedonthick
applications ofsunscreens.Thecreamorointmentshouldbeclearlyvisibleontheperson's
skin, not rubbed in until it disappears.
The face and neck should be carefully protected because they are essentially always ex-
posed.Thenose,cheeks,neck,andearsaremostfrequentlysunburned.Thelowersurfaces
ofthenoseandchinarecommonlyburnedbyreflectedradiation,particularlyaroundwater
or on snow.
Larger and more frequent applications are needed when sweating; immersion in water,
and wiping the neck and face tend to remove the preparation. Sunscreens labeled “water-
resistant” are effective after forty minutes or less of immersion. Products labeled “water-
proof” are effective after eighty minutes of immersion. No products resist immersion in-
definitely.
Theearliestchemicalsunscreen,para-aminobenzoicacid(PABA),wasintroducedinthe
1970s. It caused contact dermatitis (
Chapter 23: Allergies
)
, particularly in young children,
was water soluble and short lasting, and stained clothing; it is rarely used now. Cinnamates
or salicylates, which cause sensitivity reactions and are highly water insoluble, are used in
most currently available preparations.
Price has little relation to the effectiveness of sunscreens. Investigators for Consumers
Union, publisher of Consumer Reports, found equally effective adult sunscreens to range
in price from $0.66 to $4.28 per ounce.
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