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What does SPF and UV stand for?
Skin Institute
October 4, 2015

Broad Spectrum, UV, UVA, UVB, UVC and SPF are all terms used when discussing sunblock creams. But what do they mean? ­As summer is approaching, we thought that it might be useful for us to breakdown their meanings.

Ever wonder what the term ‘Broad Spectrum’ means?

Ultraviolet (UV) radiation is part of the invisible light spectrum that reaches earth from the sun.

These wavelengths are then classified into three categories –UVA, UVB and UVC. UVA and UVB protection is vital. Sunscreens shielding us from damage from these rays are referred to as ‘broad spectrum’.

So what is the difference between UVA and UVB?

UVA rays

  1.  Are the longest wavelength rays and therefore penetrate the deepest into the skin (the dermis).
  2.  Comprise 95% of the sun’s rays reaching earth.
  3. Are responsible for ageing (due to collagen destruction).
  4. Can cause skin cancer.
  5. Suppress the immune system of the skin making us more prone to skin cancer.
  6. Can penetrate glass.
  7. Are constant in intensity throughout the day and seasons.

UVB rays

  1. Are shorter rays and can only penetrate the surface layer of the skin (epidermis).
  2. Cause burning of the skin.
  3. Can also cause cancer.
  4. Are more intense between 11am and 2pm.

UVC rays

  1. Are lethal rays that are absorbed by the ozone layer and do not reach the earth’s surface, provided we preserve the ozone layer.

So when my sunblock states SPF, what does it actually mean?

SPF stands for ‘Sun Protection Factor’. It is a measure of how well a sunscreen will protect your skin from the UVB rays.

According to the Cancer Society, the higher the SPF number, the more Ultraviolet Radiation (UVR) is filtered and the greater the protection. Because of the number of factors involved, (e.g. time of the year, time of day and skin type) the SPF is not precise, but gives a general guide to sun protection.

No matter how high the SPF rating, no sunscreen can protect from all UVR. All sunscreens are filters allowing some UVR to pass through to the skin. For more information on sunscreen please click here.

The Skin Institute offers a range of sunscreens via their clinics or online shop. Not sure what to purchase? Talk to one of our cosmetic nurses about what sunscreen will work best for your skin.


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