Sun protection: SPF and UV filters

In short: The sun protection factor (SPF) indicates how much longer you can stay in the sun with sunscreen before the skin turns red. It mainly relates to UVB rays.

In more detail: SPF 30 lets through about 3 % of UVB rays, SPF 50 about 2 %. The “UVA” in a circle shows that UVA protection is at least a third of the SPF. Cosmetic UV filters are chemical (organic) or mineral (titanium dioxide, zinc oxide).

In Depth

• Amount: 2 mg per cm² of skin, about 6 teaspoons for the whole body. Less strongly reduces real protection.
• Reapplying: Does not extend the protection time but maintains the protection (sweating, bathing, rubbing off).
• Chemical filters: octocrylene, homosalate, octinoxate, oxybenzone. Some are criticised for possible hormonal effects or harm to coral reefs.
• Mineral filters: less absorption, may leave a white cast.
• Children: Avoid direct midday sun, use clothing and shade.

See also: Titanium dioxide (E171), INCI: reading cosmetic ingredients