A double-blind study in Europe confirms what an American study showed earlier, that use of higher SPF sunscreens such as SPF 30 resulted in people staying the sun longer. One study group was given SPF 10 and another SPF 30 sunscreen. They were not told which were which so they didn’t know if they had the higher or lower sunscreens. Even so, the SPF 30 group tended to stay out longer and also at mid day when the sun exposure is more dangerous.
The researchers believe that when people start to redden or burn, they go inside. By using higher SPF, they don’t redden as fast and stay out longer. This has implications for skin cancer because while the higher SPF is protecting from burn, its not a total block from harmful rays getting through to damage skin. Thus, people who use high SPF are lulled into a sense of safety that is not warranted.
The researchers also said this behavior is largely unconscious, and thus, difficult to control. People just reason that if they are not burning then they are not damaging their skin, which is not true. They concluded that people should be warned not to stay out longer because they are not burning.
As we have said before, the best protection against skin aging and skin cancers is the limited exposure to the sun. That doesn’t mean spending your life indoors. There are plenty of ways to stay protected and enjoy the outdoors. Use wide brimmed hats, SPF clothing, seek shade and use umbrellas.
Also, you should not take this research to mean that high SPF sunscreens are not worth using. Surely, they are. You should apply every day in the morning as part of your bathroom routine. This study is more relevant to behavior while on vacation or sun bathing.