Anyone over the age of six months should apply sunscreen daily to keep their aesthetic beauty maintained. Even those who work indoors are exposed to ultraviolet radiation for brief periods throughout the day, especially if they work near windows, which generally filter out UVB but not UVA rays.
Most sunscreens with an SPF of 15 or higher do an excellent job of protecting against UVB. SPF is a measure of a sunscreen’s ability to prevent UVB from damaging the skin. For example, if it takes 20 minutes for your unprotected skin to start turning red, using an SPF 15 sunscreen theoretically prevents reddening 15 times longer or about five hours.
Another way to look at it is in terms of percentages, SPF 15 filters out approximately 93% of all incoming UVB rays. SPF 30 keeps out 97% while SPF 50 keeps out 98%.
However, it is important to remember that no sunscreen, regardless of strength, should be expected to stay effective longer than two hours without reapplication, although our EHA Sunshield 24Hr, which is mineral based, has been shown to protect the skin for unto 24 hours (if applied adequately and reapplied after sweating or swimming). Second, “reddening” of the skin is a reaction to UVB rays alone and tells you little about what UVA damage you may be getting. Plenty of damage can be done without the red flag of sunburn being raised.
