International Academy of Cosmetic Dermatology
SUN PROTECTION FACTOR (SPF)
SPF, or sun protection factor, is a well-recognized indicator of sunscreen products for skin protection from harmful sunrays. The sun radiates visible light, as well as ultraviolet radiation (UVR). SPF measures a sunscreen product’s ability to protect the skin from ultraviolet radiation-induced redness, or “sunburn.” Within the ultraviolet spectrum, UVB radiation is much more likely than UVA to produce redness on the skin following sun exposure. Therefore, the SPF of a sunscreen represents the protection of the skin from UVB radiation.
On August 27, 2007, the Food and Drug Administration (FDA) recommended new labeling standards for sunscreens to take effect around May 2009. SPF will now be replaced by the term “sunburn protection factor” but will still reflect protection from UVB exposure. In addition, sunscreens will now have indicators of UVA protection, a causative factor in skin aging. UVA protection will be measured by a four-star system, with one star representing “low” and four stars representing “high” UVA protection.
The American Academy of Dermatologists recommends individuals use a broad-spectrum sunscreen to protect against the harmful effects of both UVA and UVB radiation. A sunscreen should have an SPF of 30 or above to protect against sunburning. A higher star UVA rating will be preferred, when sunscreen-labeling changes take effect. As always, broad-spectrum sunscreen use should be used in conjunction with other sun-protective behaviors. These include avoiding prolonged sun exposure between the hours of 10 am and 4 pm, reapplying sunscreens liberally and frequently, and wearing protective clothing and eyewear.
Melanie D. Palm, MD