If you want to spend a lot of time outside while on vacation, you should be sure to wear sunscreen. Even though “getting some sun” may be a goal of yours, getting too much of it can increase your chances of developing skin cancer and accelerate your skin’s aging process. The U.S. Food and Drug Administration, which regulates sunscreen in the United States, recommends that people use broad-spectrum sunscreens with SPF values of 15 or higher, reapplying at least every two hours.
“Broad-spectrum” means that the sunscreen blocks two different kinds of ultraviolet radiation: UVA and UVB. Both damage the skin. However, UVB light takes most of the responsibility for sunburn. UVA light goes deeper into the skin and contributes heavily to the aging effects of sunlight. The term SPF stands for “sun protection factor,” which refers to how well a sunscreen prevents UVB light from causing skin damage. The higher the SPF rating of a sunscreen, the more light it blocks and the longer it will take you to get sunburned if you’re wearing it. When properly applied, SPF 15 sunscreen prevents 93 percent of UVB rays from reaching the skin, which means that it will take you 15 times as long to get a sunburn. SPF 30 means it will take 30 times as long, SPF 50 means 50 times as long, and so on.
When applying sunscreen, put on at least one ounce, or about the same amount as a shot glass would contain. Because you need to apply it every two hours to get the sunscreen’s full benefits, over the course of a day at the beach you should be using at least a quarter of an eight-ounce bottle, and possibly half a bottle.
You may hear some myths about sunscreen use, and it’s worth taking the time to examine them. Research has not shown sunscreen to cause deficiencies in vitamin D, and you do, in fact, need to wear sunscreen even on cloudy days, as 40 percent or more of ultraviolet sunlight penetrates clouds. You may also hear that only children need to wear sunscreen, but that’s not true either. More than three quarters of a person’s lifetime sun exposure occurs after you turn 18.