If it's streaming sunshine outdoors and the sunscreen isn't handy, do as ladies in the past once did and grab an umbrella for shade, researchers say.
According to a U.S. study published in JAMA Dermatology, any fully-functioning handheld umbrella can block more than three-quarters of ultraviolet (UV) light on a sunny day. Black ones do even better, blocking at least 90 percent of rays.
"The umbrellas blocked between 77 percent and 99 percent of UV radiation," wrote Suephy Chen and colleagues at Emory University in Atlanta.
Noting that umbrellas are widely used for shade in parts of Asia - up to 45 percent of women in China - as well as the Middle East, the researchers decided to see how well regular umbrellas actually blocked UV light.
So they collected 23 working umbrellas - no fabric tears allowed - from people at their medical school. On a sunny morning they used UV devices to measure radiation just under each umbrella's fabric, and by the nose of the person using it - and then compared this to umbrella-less radiation readings.
All but one of the umbrellas was a standard, handheld rain umbrella. The other was a travel sun umbrella.
The sun umbrella blocked more than 99 percent of UV rays. Regular umbrellas worked well too, blocking at least 77 percent of UV light - and more, if the umbrella was darker coloured.
"In addition to sunscreen, I often encourage people to engage in other sun-protection measures," said Brundha Balaraman, a dermatology researcher at the Washington University School of Medicine in St. Louis.
These include wearing wide-brimmed hats and sun-protective clothing, she said.
"These are all great alternatives in situations where it may be impractical to apply sunscreen adequately...every one to two hours," added Balaraman, who was not involved in the study.
Golfers and people traveling to warm climates may especially benefit from carrying around a standard umbrella, said Balaraman.
But, she acknowledged, "It's a little more challenging to convince people to use umbrellas on a daily basis."