You know you should be wearing sunscreen, but how can you be sure that what is protecting you from harmful rays isn't inflicting another kind of potential damage to your health? We cleared up this and other (sun)burning questions with the help of Dr. Papri Sarkar, a Harvard-trained dermatologist who practices at Brookline Dermatology Associates in Brookline, Mass.
1.What's the difference between chemical sunscreens and physical blockers? Is one more effective than the other?
The wavelength of light that is damaging is ultraviolet light (UV). Chemical sunscreens and physical blockers both protect against UV rays, but do it differently. Chemical sunscreens are absorbed by the skin. They then absorb UV rays and convert them to a less dangerous wavelength (and are often released as heat). Physical blockers mostly sit on top of the skin and reflect UV rays back like a mirror would. Physical blockers, like titanium dioxide and zinc oxide, are broader- spectrum and protect against both UVA and UVB rays. Chemical sunscreens are often combined in sunscreens so they also achieve broad spectrum coverage. Products also often combine physical and chemical sunscreens to get the broadest spectrum coverage possible.
2. What ingredients should we look for on a sunscreen label? Which should we avoid?
I generally recommend products with physical blockers like titanium dioxide and zinc oxide. Unfortunately, both titanium and zinc oxide are thick and white so people don’t always like using them. Some sunblocks use micronized (smaller particle) titanium dioxide or zinc oxide so they go on more clear and patients don’t look like Casper the Friendly Ghost! Physical blocks are also less likely to cause allergic reactions in people. One ingredient to avoid, that has been shown to cause frequent allergic reactions, is PABA or para-aminobenzoic acid. With so many great sunblocks on the market, there’s no reason to use one with PABA. Many sunscreens are labeled PABA-free now to make it easier for consumers.
3. How often should we reapply?
If you’re in the water or sweating quite a bit, sunblock should be reapplied every two hours.
4. What kind of sunglasses will best protect the skin around our eyes?
Two things to look for in sunglasses are large sized lenses and the label UV 400. Large lenses like the ones found in wraparound glasses or the popular retro frames protect both the eyes and the eyelids. Glasses that are labeled UV 400 protect the eyes from 99-100 percent of both UVA and UVB light. (They block all light rays with wavelengths up to 400 nanometers.) You would be surprised at how often I see skin cancer on the eyelids!
5. Can you tell us something that we don't already know about sun protection?
One not-so-commonly-known fact is that lightweight cotton shirts (like the ones that people wear in hot summer months) only have about an SPF of 5. People think they’re protected by this clothing, but they’re really not. So put sunscreen on your whole body (even under clothing) before you leave the house, wear sun protective clothing, or cheat and use SunGuard. SunGuard is a powder that you throw in with your laundry that adds UPF 30 to all of your clothes and lasts through 20 washes. It’s inexpensive, easy and you can still wear all those cute tees you bought last summer.