ALL ABOUT: Sunscreen Protection Rating Explained: SPF.



Sunscreen Protection Ratings like SPF and PAs are fundamental when it comes understanding how to choose the perfect sunscreen. These acronyms express the sunscreen’s protection power against bad sun’s radiations UVA and UVB. However, no matter how important Sunscreen Protection Rating is important, there’s always something more crucial than that. This is making sure to wear sunscreen everyday to prevent skin from sun-induced damages. Let’s dive deep into the real meaning of SPF and make sure to get protected. Choose the sunscreen that fits you most on

UVA and UVBs: Sun’s dangerous radiation.

As you can read in many articles and guides e wrote about this issue,( ) The ultimate goal of sunscreen is to shield your skin against both UVA and UVB rays.

Exposure to UV rays can lead to DNA damage in your skin cells, and this damage can lead to skin cancer.

There are three kind of ultraviolet radiation.

  • UVA rays: This type of radiation penetrates deep into the skin, and may lead to premature skin aging and cancer.  In addition, the UVA rays penetrate more deeply into the skin and play a greater role in premature skin aging changes including wrinkle formation (photoaging). There are approximately 500 times more UVA rays in sunlight than UVB rays. 
  • UVB rays: This type of radiation is responsible for the color change in your skin after spending time outdoors—your tan or sunburn is a direct result of UVB rays, as they penetrate the epidermis. UVB rays are responsible for producing sunburn. The UVB rays also play the greatest role in causing skin cancers, including the deadly black mole form of skin cancer (malignant melanoma).
  • UVC rays: This type of radiation is completely absorbed by the earth’s atmosphere, and won’t reach your skin.

SPF and PAs: The two faces of Sun Protection.

The ultimate goal of sunscreen is to shield your skin against both UVA and UVB rays.

SPF and PA are some way to express sunscreen protection. SPF indicates the level of protection from UVB rays while PA indicates the level of protection from UVA rays.

Sun protection factor, what does UVB protection mean and how it is calculated.

The sun protection factor (SPF) measures the ability of a product to block UVB rays. The SPF indicates the ability of a product to protect the skin from actinic insult, particularly UVB radiation.

The meaning of SPF numbering is identified as an exposure time countable in the dose as duration x radiant power x area, multiple of the dose (and time) that produces an erythema. 

An SPF 50 should lead to sunburn with an exposure dose 50 times higher than that expected in the absence of protection.

For clarity it should be said that the SPF uses a biological marker, erythema, which varies individually, but is a function of the ultraviolet irradiance that actually reaches the skin. 

To a good approximation, in the first few minutes after application, the SPF may indicate the amount of radiation filtered by the product. An SPF 50 would allow no more than one 1/50 of the sun’s radiation, or 2%, to pass through, stopping 98% of it. An SPF 30 would allow no more than one 1/30 (or 3.3%) to pass, stopping just under 97%.


On average, the skin burns during the first 10-20 minutes of exposure to the sun.


Multiply the skin’s 15 minutes natural tolerance by the number that follows the SPF.

I.E. SPF 30 = 15 minutes x 30 = 450 minutes before burning


Reapply sunscreen every 2 to 4 hours as sunscreen is quick to sweat off or wash off in the water.
Warning: Sun damage is cumulative, it increase after every sun exposure. Even after years