UVA and UVB: two parts of the same sun-safety picture

A sunscreen label can feel easier to understand once you know what “broad spectrum” is meant to cover. Sunlight includes ultraviolet A (UVA) and ultraviolet B (UVB) radiation. Both reach skin, but they are associated with different effects and are not interchangeable terms.

UVB is closely tied to sunburn

The sun protection factor, or SPF, describes how well a sunscreen protects against sunburn under test conditions and when used as directed. The FDA explains that sunburn is primarily associated with UVB. That makes SPF useful, but it is only one part of choosing sun protection. A high SPF number by itself does not tell you that a product has passed the broad-spectrum test for UVA coverage.

UVA is part of the broader picture

The American Academy of Dermatology describes UVA as “aging” rays and UVB as “burning” rays. Those are useful memory cues, not a claim that one ray has only one effect. The AAD says broad-spectrum sunscreen protects against both UVA and UVB. Its label guide notes that this coverage matters for sunburn, skin cancer risk, and early skin aging. The FDA likewise explains that broad-spectrum products provide protection against UVA and UVB radiation. The AAD also notes that no sunscreen filters 100% of UVB rays, another reason to keep shade and clothing in the routine. A broad-spectrum label is a useful starting point, while correct use and reapplication still matter. In other words, an SPF number is not a summary of every kind of UV coverage. Read the broad-spectrum wording as its own label signal, then check water resistance and the application directions. The combination helps keep the two kinds of protection and the practical instructions from getting collapsed into one number.

Read the whole label

The AAD recommends choosing a sunscreen that is broad spectrum, SPF 30 or higher, and water resistant. Each phrase answers a different question. Broad spectrum indicates UVA and UVB coverage. SPF describes sunburn protection. Water resistance describes tested performance during swimming or sweating for a stated period, not an unlimited promise.

No sunscreen blocks every UV ray, and a label does not turn sunscreen into permission to stay outside indefinitely. Pair sunscreen with shade, clothing, a hat, and sunglasses when possible. Use the product as its label directs, apply enough, and reapply on schedule. If a label is hard to interpret, a pharmacist or dermatologist can help explain what it means for your situation.

At AREV, we are documenting what we learn about everyday sun care while developing our own product. The guidance in this article is general and does not describe AREV test results or product performance.

AREV Daily UV Fluid is in development. Final formula and SPF will be announced after finished-product testing. This article is general sunscreen education, not a claim about our product.

Sources

AAD: How to decode a sunscreen label — https://www.aad.org/public/everyday-care/sun-protection/shade-clothing-sunscreen/understand-sunscreen-labels

AAD: Choosing the right sunscreen — https://www.aad.org/public/everyday-care/sun-protection/shade-clothing-sunscreen/choosing-right-sunscreen

FDA: Sunscreen guidance — https://www.fda.gov/drugs/understanding-over-counter-medicines/sunscreen-how-help-protect-your-skin-sun

FDA: The sun and your medicine — https://www.fda.gov/drugs/special-features/sun-and-your-medicine