How does UVA and UVB protection work?

The sun emits different types of light rays, two of which are primarily responsible for damaging your skin: ultraviolet A (UVA) and ultraviolet B (UVB). UVB rays are shorter and can’t penetrate glass, but they’re the ones that cause sunburn.

UVA rays, which can get through glass, are more insidious because they affect your skin beneath the surfaceTrusted Source, even when you can’t feel it burning.

For that reason, you’ll want to make sure your sunscreen says “broad-spectrumTrusted Source,” “UVA/UVB protection,” or “multi-spectrum” on the label. “Broad-spectrum” is the term you’ll most often see in the United States because it’s regulated by the Food and Drug Administration (FDA).

IS SUNSCREEN FROM EUROPE OR JAPAN BETTER?

Possibly. Sunscreens from other countries have a wider variety of sun-blocking ingredients. These sunscreens list a PA factor, a measure of UVA protection that ranges from “+” to “++++.” The PA rating system was developed in Japan and is only starting to catch on here in the United States.

Monique Chheda, a dermatologist in Washington, DC, adds that “usually the two ingredients that provide UVA coverage are avobenzone and zinc oxide, so you definitely want to make sure your sunscreen has one of these.”

To recap: Both UVB and UVA rays cause skin cancerTrusted Source and signs of aging, so always opt for a broad-spectrum sunscreen with a minimum of SPF 30. Murad City Skin Age Defense SPF 50 sunscreen has a PA rating of ++++, which indicates excellent protection against UVA rays.