We all know that whenever we are in the sun we should be using sunscreen to prevent skin damage. We all heard about the consequences of too long exposure to the sun. But what actually is a sunscreen and what do the SPF numbers on it mean?
SPF stands for Sun Protection Factor and it is a factor that indicates the level of protection from UVB rays. Ultraviolet B rays can cause sunburn, age the skin and can even lead to skin cancer. Now another important type of rays are the Ultraviolet A ones (UVA). Standard SPF does not protect you from those, which is too bad because they can also cause some real mayhem to your skin – redness, photoaging, skin cancer and pigmentation changes. UVA penetrates our skin much deeper than UVB rays and we are exposed to them always – whether it’s cloudy or not and whether it’s day or night, summer or winter.
SPF tells us only about the protection factor from UVB rays. That’s why always choose a sunscreen that has specified on the package that it will also protect you from UVA rays (it can also be stated as “broad spectrum”) because they are just as dangerous to us as UVB. Unfortunately no standardized scale can be found to define level of protection against UVA rays, but remember to always pick sunscreen that will protect you from both.
Now what does the SPF number actually mean? Well it’s the ratio of radiation amount that will cause sunburn when using the filter to radiation amount causing same degree of sunburn when we’re not using the filter. For example without filter we would get sunburn after 20 minutes, while with SPF 30 filter this time will be longer by 30 times so : 20*30 = 600 minutes = 10 hours. However keep in mind that a lot of cosmetic companies tend to state much higher SPF values on sunscreens that they are in reality. The SPF factor is between 2 and 50. It’s usually best to reapply sunscreen every 3-4 hours and whenever you’re really sweating or have been swimming.
Remember that SPF only decreases the risk of sunburn and cannot protect you from skin damage in the long run. It all sounds scary but it is extremely important for all of us to remember that there is no such thing as “safe tanning”. Always protect your skin and play in the sun with moderation.