There is a lot of misinterpretation regarding Sun Protection Factors, such as how they work and what to look for when selecting a product, so let’s look at the facts.
What does the SPF number represent?
The SPF number indicates the percentage of UVB rays (burning rays) that are blocked. Unless the packaging states UVB & UVA (rays that cause aging) Broad Spectrum protection, the SPF refers only to the percentage of UVB rays that are blocked.
Many believe that the higher the SPF number, the longer they can remain in the sun without a reapplication. Although the higher number does provide more protection, it does not provide an increased timeline for safe sun exposure. All SPF products need to be reapplied, approximately every 2 hours, to be effective.
The SPF number indicates the percentage of the sun’s rays that are filtered. You would think that the protection would increase exponentially, however, this is not the case. The protection almost plateaus with a very minimal increase after an SPF of 15, however, most prefer using an SPF of at least a 30 or higher.