Protection UVB. What it means: Sun protection factor.
What it does for your skin: SPF is used to prevent UVB rays from the sun. UVB is what causes sunburn. Human skin can be exposed to sunlight without being harmed to some degree, what we call MED (Minimum Erythematous Dose). This is the sunburn threshold. The use of SPF sunscreen increases this time limit, thus preventing your skin from becoming reddened and burned.
How it works: SPF is tested on a panel of 10 to 15 people (depending on the country and protocol chosen) and compares how long it takes for UVB to cause skin redness. So an SPF 30 means that if it takes 10 minutes for redness to appear on unprotected skin, it will take approximately 30 times for the same symptoms to appear on the skin if they are using the SPF 30 correctly.
