Staying Sun Safe: Confessions of a Former Tanner

Sandra A. Fryhofer, MD


May 03, 2011

In This Article

Sun Protection Factor and UV Protection

Sun protection factor (SPF) applies only to UVB wave lengths. There is no equivalent rating system for UVA rays. SPF compares the amount of time needed to produce sunburn on protected compared with unprotected skin. A higher SPF means greater protection, but a sunscreen with an SPF of 30 does not protect twice as well as one with an SPF of 15. Sunscreens with SPF of 15 block 93% of UVB rays and sunscreens with SPF of 30 block 97% of UVB rays. A 4-star system rating for UVA protection has been suggested, but the FDA has yet to approve any system for rating UVA protection for sunscreens.[9] Certain ingredients like zinc oxide and titanium dioxide provide protection against both UVA and UVB rays.

The AAP guidelines dictate use of sunscreen with SPF of at least 15.[1] The AAD recommends starting with SPF of 30.[20] For me and my family, I prefer a higher SPF: never less than an SPF 45 for outdoor activities.

Sunscreen Facts: Regular Sunscreen Use Prevents Skin Cancer

Regular use of sunscreen prevents actinic keratosis (a squamous cell cancer precursor). The AAP's UV radiation exposure update comments on the lack of studies showing melanoma or basal cell cancer prevention with use of sunscreen. A 10-year study published in the January 2011 issue of the Journal of Clinical Oncology, however, provides a different view and suggests that melanoma may indeed be prevented by regular use of sunscreen.[21]


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