Sunscreen Flashcards
What does SPF stand for? What does it measure?
SPF: sun protection factor
Measures ratio of the minimal dose of solar radiation that produces perceptible erythema on sunscreen-protected skin compared to unprotected skin)
Is SPF related to time or amount of solar exposure?
Amount
What is minimum erythema dose?
Smallest amount of sunlight exposure necessary to induce a slight redness of skin within 24h after exposure
At what number does SPF plateau?
SPF 15 (beyond this, not much diff in protection)
How long before going outdoors should you apply sunscreen?
at least 15 min before
Where to apply sunscreen?
Everywhere except eyes & mouth
How often to reapply sunscreen?
at least Q2h (more if swimming or sweating)
To use sunscreen or insect repellent first?
Sunscreen
What is the minimum age to use sunscreen?
6 months
What do physical sunscreens contain?
inorganic filters e.g. zinc oxide, titanium dioxide
How do inorganic sunscreens work?
reflect & scatter UV light over wide range of wavelengths (UVA, UVB)
What are 2 advantages and 2 disadvantages of using inorganic sunscreens?
Advantages
- less irritating to skin
- works instantaneously
Disadvantages
- leaves a whitish stain
- can feel heavy on the skin
What do chemical sunscreens contain?
aromatic compounds (cinnamates, salicylates, benzophenones)
How do organic sunscreens work?
absorb UV radiation & convert it to negligible amount of heat (e.g. cinnamates, salicylates)
What are 3 advantages and 2 disadvantages of using organic sunscreens?
Advantages
- more resistant to water & sweat
- does not leave behind white stain
- more complete UV protection
Disadvantages
- takes longer to work (apply ≥15min before going out)
- may cause skin irritation
