There are so many jargons when it comes to sunscreens and we know that it can be so very confusing. In this simplified, summarised and condensed all-you-need-to-know guide, we tell you the difference between UVA, UVB, SPF and PA.

When the skin feels direct sun exposure and you feel the burning sensation, in scientific terms, this means ultraviolet light is penetrating the epidermis causing the skin to react by producing melanin, aka tanning your skin. We know having that healthy glow from tanning looks great, but over time it causes just the opposite –  change in skin texture, wrinkling, age spots or worse, skin cancer. 

Guide to Sunscreens

Credit: Coola

What’s the difference between UVA and UVB rays?

Light travels in different wavelengths and there are actually UVA, UVB and UVC rays. UVC rays are absorbed by our Ozone layer while UVA and UVB rays are able to penetrate it and reach the Earth’s surface. 

Ultraviolet A or UVA

  • Long waves
  • Penetrates deep into dermis (skin’s thickest layer)
  • Damages skin collagen
  • Causes premature skin aging, wrinkles

Ultraviolet B or UVB

  • Short waves
  • Penetrates the skin surface
  • Causes sunburns

What about SPF and PA?

You’ve probably come across Sun Protection Factor (SPF) and Protection Grade (PA) when purchasing sunscreens. Here’s what it means:

Sun Protection Factor or SPF

  • Measure of sunscreen’s ability to block UVB only
  • If it takes 10 minutes for your unprotected skin to turn red, SPF 15 prevents reddening 15 times longer – around 2.5 hours
  • There is no strict regulation on how brands label their products therefore SPF 100 doesn’t mean that the sunscreen will protect you 100 times longer
  • SPF 15 filters out approximately 93% of UVB rays, SPF 30 keeps out 97% and SPF 50 blocks 98%

Protection Grade of UVA or PA

  • Japanese measurement of sun protection against UVA
  • Based on the Persistent Pigment Darkening (PPD) reaction reading at 2-4 hours of sun exposure
  • Protective level of strength from PA+ (light) to PA++++ (strong)

Remember kids, there is no safe way to tan so protect your skin from those harmful rays! Find out what type of sunscreen is for you at Part 2 of our guide!

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