Sun Protection
How it Works
SPF factor and sun tanning
Take notes from the ppt to answer the
following questions:
1. What does SPF stand for?
2. How do UVA rays differ from UVB
rays?
3. What does SPF on sunscreen
indicate?
4. What should you consider when
using a sunscreen?
5. How much sunscreen should you
apply?
SPF
• SPF stands for Sun Protection Factor
• The SPF rating system was developed
in 1962 by Franz Greiter.
• The SPF rating system applies to UVB
rays, the rays responsible for sunburn.
UVA Rays
• UVA - UV rays that have the longest
wavelength.
• UVA rays account for up to 95% of the UV
radiation reaching the Earth’s surface and
damage skin by penetrating deeper than UVB
rays. UVA rays cause skin cancer and
wrinkles.
• Tanning booths primarily emit UVA rays.
• There is currently no approved SPF rating
system that measures UVA rays.
UVB Rays
•
UVB - UV rays that have
shorter wavelengths than
UVA rays.
•
UVB rays damage the
skin’s more superficial
layers. The intensity of
these rays varies by
season, location, and
time of day (the most
significant amount hits
the U.S. between 10 am 4 pm from April to
October).
Sunscreens
•
SPF indicates how long it will take for UVB rays to redden skin when
using a sunscreen, compared to how long skin would take to redden
without the product. Example: Someone using a sunscreen with an
SPF of 30 will take 30 times longer to redden than without the
sunscreen.
•
You need protection from both kinds of rays. Look for a sunscreen
with an SPF of 15 or higher, plus some combination of the following
UVA-screening ingredients: stabilized a avobenzone, ecamsule
(a.k.a. Mexoryl), oxybenzone, titanium dioxide, and zinc oxide. You
may see the phrases multi spectrum, broad spectrum or UVA/UVB
protection on sunscreen labels, and these all indicate that some UVA
protection is provided. However, because there is no consensus on
how much protection these terms indicate, such phrases may not be
entirely meaningful.
•
You should apply 1 ounce (2 tablespoons) of sunscreen to your entire
body 30 minutes before going outside. Reapply every two hours, or
immediately after swimming or excessive sweating.
Sunprint Paper from the Sunscreen Lab
SPF 0
SPF 4
SPF 8
SPF 15
SPF 45
Unknown