I always put on sunscreen when I'm going into the sun, but how often should I be reapplying throughout the day?
Generally speaking, SPF stands for "sun protection factor," which determines how long you can stay in the sun before getting sunburnt. If you are going to be outside in the sun for a prolonged period of time, be sure to use SPF 30 or above and reapply every one to two hours. Chemical sunscreens, (look for chemicals like oxybenzone and avobenzone), should be applied 30 minutes prior to sun exposure so they have time to be absorbed. If you are going to be swimming or excessively sweating, reapply twice as often as mentioned above.