What's the difference between UVA and UVB?
Ultraviolet A
(UVA) rays make the skin tan; ultraviolet B (UVB) rays cause skin to
burn. But don't be fooled: A tan isn't healthier. "Both suntans and
sunburns are signs that skin cells have been damaged by radiation from
the sun," says Kavita Mariwalla, M.D., director of Mohs and Dermatologic
Surgery at Continuum Health Partners in New York City. UVB used to get
all of the blame for causing skin cancer, but new research shows UVA is
equally damaging. This is particularly worrisome since UVA rays are 30
to 50 times more prevalent, and they penetrate deeper into skin cells.
What does SPF stand for? Is a higher number more effective?
An
SPF, or sun protection factor, indicates a sunscreen's effectiveness at
preventing sunburn. "If your child's skin reddens in 10 minutes without
sunscreen, SPF 15 multiplies that time (10 minutes) by 15, meaning
she'd be protected from sunburn for approximately 150 minutes or 2 1/2
hours," says Sancy Leachman, M.D., Ph.D., director of the Melanoma and
Cutaneous Oncology Program at the University of Utah's Huntsman Cancer
Institute in Salt Lake City. Of course, this depends on an adequate
application of sunscreen and is based on SPF calculations with
artificial instead of natural sunlight. The American Academy of
Pediatrics (AAP) recommends using sunscreens with at least an SPF of 15,
which blocks 93 percent of UVB rays. Higher SPFs provide even greater
protection, but only to a certain point: SPF 30 blocks 97 percent of UVB
and SPF 50+ (the maximum SPF you'll find on sunscreen labels due to new
Food and Drug Administration (FDA) rules) blocks 98 percent.
What should I look for in a sunscreen? Are sunscreen sticks and sprays as effective as lotions?
As
long as you're using a sunscreen with SPF 15 or higher that's
broad-spectrum (meaning it blocks both UVA and UVB rays), it doesn't
matter whether you use a lotion, cream, gel, stick, or spray. "The
problem with some of the easiest and most cosmetically acceptable
products is that they often do not adequately block both UVA and UVB.
You must look at the ingredients, but the best sunscreen is the one your
child agrees to wear," Dr. Leachman says. That said, sprays that
contain the "right stuff" are great for on-the-go toddlers and
preschoolers. Some young children are sensitive to certain sunscreen
ingredients. To test for reactions, apply a small dab on the inside of
your child's upper arm and check the area in 24 hours for signs of
redness or rash. Sunscreens with titanium dioxide or zinc oxide are
often less irritating because the ingredients aren't absorbed into skin.
If your child is going to be in the water or getting sweaty, look for
water-resistant sunscreens (the FDA has done away with waterproof and
sweatproof claims). The new water-resistant labels state how long --
either 40 minutes or 80 minutes -- the sunscreen provides protection
before you need to reapply it.
