What Is SPF: How Can Mixing SPF Can Be Harmful?

With summers around the corner, it has become important for people to choose the best sunscreen available. However, in order to understand which sunscreen would suit their skin the best, it is important to understand what sun protection factor (SPF) is and how one should choose it.

Technically, SPF tells about the amount of protection a particular sunscreen offers against the ultraviolet radiation from the sun. That is, it is a measure of how much invisible radiation from the sun is necessary to burn the skin applied with sunscreen, as compared to normal, unadorned skin.

For example, if an individual can stay in the sun for 20 minutes before the skin starts to redden, applying SPF 15 sunscreen can provide an extra 15-minute protection in the sun. But, it is highly important to reapply the sunscreen every two hours because it may get wiped off due to sweat and other circumstances. Therefore, the time gap really does not matter much.

One of the misconceptions associated with sunscreen use is that the protection increases linearly with the greater SPF number. For example, if a person decided to use SPF 30 instead of SPF 15, it does not mean that the former will offer double protection as compared to the latter.

While SPF 15 may block 93 percent of UV radiation from the sun, SPF 30 sunscreen may just block up to 97 percent of the radiation. That is, the sun protection factor does not increase linearly with the increase in the SPF.

Another misconception is that if people mix two SPFs, they will end up getting a new SPF which is a combination of both. However, that is not true. That is, mixing SPF 15 and SPF 30 won't result in SPF 45 sunscreen. Chances are that people might end up diluting the SPF of the original sunscreens in an attempt to increase it. In addition, it may lead to adverse skin reaction as the chemical components in each SPF are specially designed to work in a certain fashion.