Majority of US consumers use sunscreen incorrectly

Most American consumers don’t know that layers of different SPF factors do not add up to provide a higher level of protection from the sun’s rays. The common misconception is just one of many surrounding sunscreen usage, and a survey by the American Academy of Dermatology (AAD) highlights that many consumers are still confused over how to use sun protection products safely and effectively.

“Only 32% of respondents knew that an SPF30 sunscreen does not provide twice as much protection as an SPF15 sunscreen. Moreover, only 45% knew that a higher SPF sunscreen does not protect you from the sun longer than a lower SPF sunscreen,” said the press release on the survey.

Rather than protecting the skin for longer, a higher SPF rating means a higher percentage of the sun’s rays are blocked from penetrating the skin. Even if a layer of SPF15 was applied on top of a layer of SPF30, the level of protection will be no higher than the highest SPF applied, which in this case would be 30. "A sunscreen with an SPF of 30 blocks up to 97% of the sun's rays. Higher SPFs block slightly more rays, but a higher number SPF does not allow you to spend more time outdoors without reapplication; all sunscreens should be reapplied every two hours, or after swimming or sweating,” commented dermatologist Abel Torres, president of the AAD.

Another study, by the John Hopkins University School of Medicine and published in the Journal of the American Academy of Dermatology last month, investigated the sun protection measures taken by people with a history of non-melanoma skin cancer. While the authors found these people were more likely to wear protective clothing, spend more time in the shade and use SPF products more seriously than the control subjects, these people still got sunburn as often as the control subjects without a history of skin cancer. The authors concluded that this was down to their ineffective use of sun protection products, or a reliance on just sunscreen as opposed to the other methods of protection.

"Our results reinforce the importance of everyone using multiple types of sun protection; people who rely only on sunscreen may not be applying enough, covering all their exposed skin or reapplying often enough to shield themselves from the sun's harmful UV rays,” said dermatologist Anna Chien, one of the study's co-authors.

The AAD recommends everyone use a broad-spectrum, water-resistant sunscreen with and SPF of 30 or higher, no matter the skin type.