SPF measures only one type of harmful light from the sun (UVB) and is not the only factor to consider when you choose a sun- screen. You must make sure you have adequate UVA protection as well. Let me explain.
UV light from the sun is divided into three categories:
A, B, and C—based on intensity: UVA, UVB, and UVC.
The most harmful types of rays are UVA and UVB. UVC is absorbed by the ozone layer. Almost all sunscreens provide coverage to protect against UVB, and SPF is used to measure that protection only. But only a few sunscreens protect against UVA, and SPF does not account for UVA protection.
UVA is especially damaging because unlike UVB, it can pass through glass and harm you while you are driving or sitting by a window. It is also the type of UV light that is most closely linked to melanoma, the deadly skin cancer.
The best sunscreens contain both UVA and UVB protection.
What should you watch out for when reading sunscreen labels? Find that out, and more, in Dr. Nakhla’s comprehensive skin care book: The Skin Commandments: 10 Rules to Healthy, Beautiful Skin available on Amazon.com. You can also schedule a skin care consultation with Dr. Nakhla at OC Skin Institute by visiting www.ocskininstitute.com or calling (714) 547-6111.