To Block UV Rays, Even the Poorest Handheld Umbrellas Work
(HealthDay News) – Handheld umbrellas are effective at blocking ultraviolet radiation (UVR), according to a study published online March 20 in JAMA Dermatology.
Josette R. McMichael, MD, from Emory University in Atlanta, and colleagues used a meter at 11 a.m. on a sunny April day (UV index 8) to measure UVR (both UV-A and UV-B) in microwatts per square centimeter. Measurements were taken without an umbrella three times and twice for each of 23 handheld unbrellas. Measurements were taken holding the meter aimed toward the sun both holding the meter 1cm beneath the umbrella fabric and holding the meter approximately 1cm from the researcher's nose.
The researchers found that the majority of umbrella canopies had a diameter between 81 and 99cm, and 14 of the 23 were black. Without an umbrella, the UVR measurements were 6,563, 6,783, and 6,913µW/cm². For UVR readings taken from 1cm under the umbrella fabric, measurements ranged from 26–1,714µW/cm². For measurements taken 1cm from the researcher's nose while holding the umbrella overhead, UVR ranged from 67–1,256µW/cm². The umbrellas blocked between 77% (white Totes) and 99% (silver Coolibar) of UVR.
"The poorest performing umbrella still blocked an average of 77% UVR," the authors write.
One author disclosed financial ties to pharmaceutical companies and collects royalty payments for evaluating products.