How Often You Should Be Reapplying SPF

Despite its imperative nature in regard to sun safety and skin health, SPF nevertheless remains a mysterious concept to many, with the question of how often to reapply sunscreen being especially baffling. Moreover, the contradictory information available online often complicates the equation more than it elucidates effective sun safety practices, raising more questions than it answers. Which SPF is best for deflecting the sun's ultraviolet rays? Is a spray more effective than a lotion SPF? And, of course, there's the question of application frequency. With regards to the latter, the answer is actually much simpler than it would seem.

According to The Skin Cancer Foundation, sunscreen must be applied in two-hour intervals to sustain the veil of protection over the skin's surface. In addition, the Foundation advises sunscreen consumers that the average person requires approximately one ounce of sunscreen per application, a measurement that ensures the formula's SPF, or Sun Protection Factor, is evenly distributed in a great enough volume across the skin to properly cushion skin against UV rays. Furthermore, the American Academy of Dermatology states that sunscreen necessitates between 15 to 30 minutes to sink into the skin before achieving efficacy. Therefore, if your skin still possesses the notorious, anemic look sunscreen lends just after an application, you aren't quite ready to venture into the sunshine.

Unfortunately, applying a shot glass's worth of sunscreen for every two hours you spend basking in the sun's rays isn't quite enough if you're perspiration-prone or hydrophilic. According to The Huffington Post, those taking a dip or diving to catch a volleyball demand more frequent sunscreen reapplications, due to water exposure.

Before you gear up for your next hike through Topanga Canyon, beach volleyball game in Montauk, or sailing expedition on Biscayne Bay, give yourself ample time to lather up with sunscreen — and set a timer to remind yourself of reapplications. After all, nothing puts the kibosh on a serene, midsummer weekend's adventure faster than a serious sunburn.

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