Don’t Just Stand Under My Umbrella
Sunscreen is the typical and effective way to prevent sunburn, but how does it compare to staying in the shade? A recent study compared the two by randomizing two groups of sun-seekers – those wearing 100 SPF sunscreen lotion and those that chose to stay under an umbrella. The study was conducted over two days in August at Lake Lewisville, Texas.
The shade group was told to stay under their commercial beach umbrella without wearing clothes that could block the evaluated areas for 3 ½ hours at a time; subjects could leave the umbrella for up to 30 minutes as long as they covered up. The group using sunscreen were instructed to apply the product liberally to all exposed areas of skin 15 minutes before beach exposure, to reapply the sunscreen at least every 2 hours or as needed, and the amount used was measured and recorded. They were instructed to stay at the beach for 3½ hours between 10 AM and 2 PM, with 30 minute shade breaks as needed. Positioning under the umbrella was monitored and adjusted as the solar angle changed. Participants were not permitted to engage in water activities and were placed at least 33 meters away from the water. Sun exposure was avoided after the conclusion of the study until evaluation. Researchers also monitored the intensities of UV rays during the study period (between 10 AM and 2 PM). Both groups were evaluated for sunburn by a clinician who was blinded to the randomization 22 to 24 hours after sun exposure.
The results showed that while both groups demonstrated a significant increase in global sunburn scores from baseline, the total number of sunburned areas was 142 for the umbrella group and 17 for the sunscreen group. Though shade is often mentioned as a way to prevent sunburn, the magnitude of reduction to exposure of UV rays and clinical effectiveness may be less than expected. The authors conclude that umbrella shade alone is not enough sun protection. They state that even though the 100 SPF lotion was more effective, neither method alone prevented sunburn completely under actual use conditions, highlighting the importance of using combinations of sun protection practices to optimize protection against UV rays.
Byline: Martha L. Sikes, MS, RPh, PA-C
Posted: April 18, 2017
Source: JAMA Dermatology
Adapted from the original article.