- Sunscreen Ingredients
- Sunscreens ingredients can be divided into compounds that physically
block radiation or compounds that absorb radiation. The radiation blockers
are very effective at reducing the exposure of the skin to both UVA and
UVB radiation. Older formulations like zinc oxide are opaque and may be
cosmetically unacceptable. However, a newer formulation of micronized titanium
dioxide is not as opaque and provides excellent protection. The radiation
absorbing ingredients are differentiated by the type of radiation they
absorb - UVA absorbers and UVB absorbers.
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- Picking the Proper Sunscreen
- The SPF measures the amount of UVB absorption, but there is no method
of reporting the UVA absorption. The only way to determine if a sunscreen
protects against UVA and UVB radiation is to look at the ingredients.
A good broad-spectrum sunscreen should have an SPF of at least 15 and
contain avobenzone, titanium dioxide, or zinc oxide.
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- Applying Sunscreen Properly
- Most people use sunscreen improperly by not applying enough. They apply
only 25% to 50% of the recommended amount. Sunscreen should be applied liberally
enough to all sun-exposed areas that it forms a film when initially applied.
It takes 20-30 minutes for sunscreen to be absorbed by the skin, so it should
be applied at least a half an hour before going out in the sun. Sunscreen
should also be the last product applied especially on the face since some
sunscreens can break down in the presence of water contained in water-based
foundations and moisturizers.
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- Reapplying Sunscreen
- Most instructions on sunscreen labels recommend reapplying sunscreen "frequently",
but the definition of "frequently" is vague. A common instruction
is to reapply sunscreen regularly when in the sun. However, one study has
shown that reapplying sunscreen 20 to 30 minutes after being in the sun
is more effective than waiting 2 hours. It is possible that this time period
is more effective because most people do not apply enough sunscreen initially,
and this second application approximates the actual amount needed. Sunscreen
should also be reapplied after swimming, excessive sweating, or toweling.
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- Daily Sunscreen
- Sunscreen should be applied daily. The daily use of a low-SPF sunscreen
(15) has been shown to be more effective in preventing skin damage than
the intermittent use of a higher SPF sunscreen.
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