It is a known fact that the UV rays from the sun are harmful and they not only cause premature ageing of the skin, but also skin cancer in more serious cases. However, I realised that not many people know the difference between UVA and UVB rays, as well as how SPF in skin care products works. Here, I try my best to compile the information that I have regarding this topic.
There are actually 3 different types of UV rays that come from the sun: UVA, UVB and UVC. Out of these three, however, only UVA and UVB reach the earth’s surface as we’re protected from UVC with the help of the ozone layer.
UVA rays are longer in wavelength and have less energy than UVB rays. They are the ones that cause premature skin ageing and loss of elasticity in the skin. UVB rays are shorter in wavelength and have more energy. Although they penetrate less into our skin, they are more dangerous as these are the ones that cause skin cancer.
The SPF number in skin care and cosmetic products is actually an indication of how long it is safe for you to stay exposed under the sun. For example, if you usually get redness or your skin starts to act up after 10 minutes under the sun, a product with SPF25 will protect you for 10 X 25 minutes, after which you’ll have to reapply. It’s recommended to reapply once after every 2 hours but I say go with whatever feels most comfortable for your skin. If your skin isn’t that sensitive to the sun, you don’t need a product with too high an SPF. Usually, if you want to be protected against both UVA and UVB rays, try looking for a product that says it’s effective against them both.
It’s also good to know that SPF of different products don’t add up. When you, say, apply a moisturiser with SPF15 and a foundation with SPF20 on top of it (or whichever one first), the final SPF you have is only 20 and not 35.
Sunscreen Vs. Sunblock
Finally, there is a difference between sunscreen and sunblock. While sunscreen doesn’t prevent all of the UV rays from reaching you, sunblock does just that. I don’t recommend using sunblock for normal daily usage because, well, we all need some vitamin D! It’s a great idea to use sunblock instead, for when we are doing intensive outdoor sports and don’t need to care if our skin looks greasy or sticky.
I hope this little article helps and have a safe summer!