sun protection and SPF Flashcards
briefly outline UVA
longer wavelength 320- 380 nm
less erythrogenic
penerates the skin more deeply and contributes to photoaging and photosensitivity
not filtered by window glass
UVB
shorter wavelength 290-320
most erythrogenic and melanogenic type of radiation
cause of sunburn,suntan, skin cancer and photoaging
UVC
shortest wavelngth 270- 290
absorbed by the ozone layer
does not reach the earth’s surface
what reflects both UVA and UVB radiation, and is visible on the skin, which
may not be cosmetically appealing?
sun blocking agents
whatt do the sun blocking agents contain?
titanium dioxide
zinc oxide
iron oxide
what obsorbs energy from uvb and in some cases uva?
sunscreens
what do the organic compunds that absorb uv light or opaque material that reflect both include?
PABA and derivatives
salicylates, cinnamates, benzophenones, camphor
what do regular use of sunscreen help reduce?
risk of actinic keratoses
squamous cell carcinomas
what is the minimal erythemal dose(MED)?
he time (in minutes) needed for skin to redden on
exposure to radiation from the sun. The greater the melanin content of the skin, the longer the MED
what is the sun protective factor(SPF)
In order to measure or grade the effectiveness of sunscreens, the sun protection factor
SPF = MED of sunscreen - protected skin / MED of unprotected skin.
SPF only measures UVB, not UVA. SPF indicates how much longer a person can stay out in
the sun without being burned. Eg. If you normally burn after 12 min in the sun, sunscreen
with a SPF of 15 would allow you to stay out in the sun for 15 times longer i.e.
12 min x 15 SPF = 180 min
skin types and spf
-I fair skin, blue/green eyes, little or no freckles 6-24
-II fair skin, blue eyes, blonde or brown hair 5-20
-III fair skin, brown hair and eyes 4-16
-IV olive, light brown skin, dark brown hair, dark eyes 3-12
-V dark brown skin 2-8
-VI black or dark brown skin, brown eyes, black or dark
brown hair
1-4
