Reading a Sunscreen Label: SPF, PA+++ and What Actually Matters

Sri Lanka sits close to the equator, which means high UV year-round — cloud cover included. Sunscreen is not a beach product here; it is a daily one. But the labels are genuinely confusing, so here is what each part means.

SPF is about UVB

SPF measures protection against UVB — the wavelength that burns. SPF 30 filters roughly 97% of it, SPF 50 about 98%. The jump from 30 to 50 is small in theory and larger in practice, because nobody applies the laboratory amount. Buy 50 and you have margin for error.

PA+++ is about UVA

UVA penetrates deeper, does not burn, and drives most photo-ageing and pigmentation. The PA rating (a Japanese system, common on Korean and Japanese sunscreens) grades it: PA+++ is high, PA++++ is highest. European labels use a circled "UVA" mark instead. If a sunscreen advertises SPF but says nothing about UVA, it is only doing half the job — and for anyone treating dark spots, UVA is the half that matters.

Chemical or mineral?

Mineral filters (zinc oxide, titanium dioxide) sit on the surface, start working immediately, and rarely irritate — but can leave a white cast. Chemical filters absorb UV and convert it to heat; modern ones such as Tinosorb and Uvinul are elegant, invisible, and photostable. Neither is inherently safer. Korean and European chemical filters are generally more pleasant to wear daily in humidity, which matters, because the sunscreen you actually apply beats the one you avoid.

How much, how often

Roughly two finger-lengths for the face and neck. Reapply every two hours outdoors, and after swimming or heavy sweating. Indoors near a window, once in the morning is enough — glass blocks most UVB but not all UVA.