What 'Broad Spectrum' Really Means, and Why SPF Alone Won't Save You From UVA
There's one word on the label that decides whether you're protected from the UVA rays that age skin and drive cancer.
SPF primarily measures UVB (sunburn) protection; only sunscreens that pass the FDA's broad-spectrum test, requiring a critical wavelength of at least 370 nm, provide UVA protection proportional to their SPF.
The American Academy of Dermatology advises shoppers to look for the words 'broad spectrum' alongside SPF 30 or higher, since SPF by itself does not guarantee UVA coverage.
Questions we get a lot
What does 'broad spectrum' mean on a sunscreen label?
It means the product passed the FDA's broad-spectrum test by meeting a critical wavelength of at least 370 nm. That indicates it protects against UVA rays in addition to the UVB that SPF measures. Broad-spectrum products deliver UVA protection proportional to their SPF.
Is a high SPF enough to protect against aging?
Not on its own. SPF mainly reflects UVB and sunburn protection, while UVA drives much of photoaging. To guard against aging rays you need a product labeled 'broad spectrum.' Dermatologists recommend broad spectrum SPF 30 or higher.
r/SkincareAddiction: 'My sunscreen is SPF 50 but doesn't say broad spectrum. Am I still protected from aging rays?'