Spotlight on Sunscreen- Difference between UVA and UVB

About Ultraviolet A (UVA):

UVA has longer wavelengths and can even penetrate windows. UVA rays is associated with ageing the skin and tanning, but it can also burn the skin. UVA is slightly less intense than UVB rays; however, UVA rays penetrates the skin more deeply which compromises the innermost part of the top layer of skin, which is where most skin cancers occur. A tan result from the skin's attempt to prevent further damage by darkening. UVA causes skin cancer and early ageing over time.

Up to 95% of the UV light that reaches the earth is UVA. Throughout the year, these rays remain at the same intensity during daylight hours. This means that we are all exposed to high levels of UVA radiation over the course of our lifetimes. You can remain protected from UVA rays by using a broad-spectrum sunscreen. Broad spectrum means that is protects from both UVA and UVB. Traditionally, sunscreens only protected from UVB associated with burning, therefore it is important to ensure your sunscreen is broad spectrum and SPF 50+.

UVA penetrates windows and cloud cover. It is common for people to think that if they are indoors, they do not need to wear sunscreen; however, if you are inside near a window you are exposed to UVA. Therefore, it is good habit to:

  • apply sunscreen every day as part of your morning routine as the last step of your skincare and before your makeup on your face,
  • apply sunscreen over your limbs that are not covered by clothes
  • reapply every two hours is also good practice!

About Ultraviolet B (UVB):

UVB has a shorter wavelength than UVA but is associated with burning the skin. UVB penetrates and damages the outermost layers of the skin which causes burning. UVB’s intensity fluctuates, with the strongest rays that cause the most damage to the skin, occur mid-morning to mid-afternoon. They are the most intense during warmer months of the year however are damaging all year round. Additionally, UVB rays can be damaging on reflective surfaces such as ice and snow.

The Sun Protection Factor (SPF) listed on sunscreen product labels is related to UVB. The SPF rating indicates you how long it would take the sun's radiation, which includes some UVA, to cause your skin to turn red when using that product as opposed to not wearing sunscreen. UVB rays are the deadliest when considering melanoma.

Sunburns can dramatically increase the chances of melanoma. If you have experienced more than five sunburns in your life you are have doubled the risk of melanoma!

Melanoma is a skin cancer that forms in the skin cells called melanocytes. Melanoma risk increases with exposure to UV radiation from the sun or other sources such as solariums. Knowing the risks associated with exposure to UV is important to protecting yourself from melanoma.

Next month's Spotlight on Sunscreen will cover application of sunscreen – how much to apply, how to apply it and when. See you then!


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