Sabtu, 25 Mei 2013

Facts About Sunscreen & Sunblock

UV A vs UV B

Picture below tells about the wavelength & hazard to human skin that may caused by radiation of UV A and UV B



Sunscreen or Sunblock ?

The different terms between sunscreen & sunblock depends on the ingredients, but both can provide UV A & UV B rays protection. 


Difference
Sunscreen
Sunblock
How it works
By being absorbed into the skin & change UV rays wavelength into less harmful energy

By coating the skin. Sunblock ingredients block the UV rays from reaching the skin
Characteristics related to sunlight
Sunscreen ingredients may deteriorate at a faster rate once exposed to sunlight. Therefore, UV rays can still be absorbed into skin

Sunblock reflects the UV rays away
Durability
Heavy sweating & towelling off can wear off the sunscreen
Depends on the waterproof characteristics. Reapplying sunblock is necessary after swimming

Sunscreen & Sunblock Ingredients


The picture can be explained by this table  


Ingredients
Protection from UV B
Protection from UV A
Notes
Physical Ingredients


Titanium dioxide
Yes
Short wave UV A

Zinc dioxide
Yes
Yes (short & long wave)
The best broad spectrum protection

Chemical Ingredients


Para Amino Benzoic Acid (PABA)
Yes
No
May cause irritation, allergy, cancer

Avobenzone
Limited
Extensive

Cinoxate
Extensive
Limited

Dioxybenzone
Extensive
Considerable

Ecamsule/Mexoryl SX
Extensive
Limited

Homosalate
Extensive
Minimal

Menthyl anthranilate
Extensive
Considerable

Octocrylene
Extensive
Limited

Octyl Methoxycinnamate
Extensive
Limited

Octyl Salicylate
Extensive
Minimal

Oxybenzone
Extensive
Considerable
May cause allergy, disruption of hormones (not recommended for pregnant women)

Padimate O
Extensive
Minimal
Derivate of PABA
Phenylbenzimidazole
Extensive
Minimal

Sulisobenzole
Extensive
Considerable

Tinosorb
Yes
Yes

Trolamine salicylate
Extensive
Minimal



How much SPF should I use?



FACTS : Higher SPF doesn't provide better protection. High SPF will lead your skin exposed by more chemical ingredients. You should know that :
  • SPF 15 product blocks about 94% of UVB rays 
  • SPF 30 product blocks 97% of UVB rays
  • SPF 45 product blocks about 98% of rays 

Actually SPF that we need depends on UV index. UV index determines how long the skin can last before sunburn occurs.


Dermatologists recommend SPF 15 for indoor activity & SPF 30 for outdoor activity. 
  • apply to dry skin, 15 - 30 minutes before sun exposure
  • re-apply after towelling off/swimming/heavy sweating
  • re-apply every 2 hours 

Reference

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