Term that refers to a sunscreen’s ability to protect the skin from both UVA and UVB rays from the sun. Current FDA regulations state that in order for any SPF-rated product to make a broad spectrum claim, it must pass what's known as a critical wavelength test and have the required testing done to confirm its SPF rating is 15 or greater. Any SPF-rated product below SPF 15 can only make a broad spectrum claim that applies to sunburn prevention, not skin aging (wrinkles, brown spots) or skin cancer.
It is critical to look for "broad-spectrum protection" on the label or you can check the active ingredients to see if one or more of these reliable UVA-protecting ingredients are listed: titanium dioxide, zinc oxide, avobenzone (also known as butyl methoxydibenzoylmethane), Mexoryl SX (ecamsule), or, outside the U.S., Tinosorb.
More details from the FDA regarding the use of "broad-spectrum protection":
Products that pass the broad spectrum test will provide protection against both ultraviolet B radiation (UVB) and ultraviolet A radiation (UVA). Sunburn is primarily caused by UVB. Both UVB and UVA can cause sunburn, skin cancer, and premature skin aging. A certain percentage of a broad spectrum product’s total protection is against UVA.
The new labeling will also tell consumers on the back of the product that sunscreens labeled as both “Broad Spectrum” and “SPF 15” (or higher) not only protect against sunburn, but, if used as directed with other sun protection measures, can reduce the risk of skin cancer and early skin aging. For these broad spectrum products, higher SPF (Sun Protection Factor) values also indicate higher levels of overall protection. By contrast, any sunscreen not labeled as “Broad Spectrum” or that has an SPF value between 2 and 14, has only been shown to help prevent sunburn.
Sunscreen products that are not broad spectrum or that are broad spectrum with SPF values from 2 to14 will be labeled with a warning that reads: “Skin Cancer/Skin Aging Alert: Spending time in the sun increases your risk of skin cancer and early skin aging. This product has been shown only to help prevent sunburn, not skin cancer or early skin aging."