What Does Sunscreen Do? SPF, PA Ratings and Mineral vs Chemical Filters
How sunscreen works, what SPF and PA numbers mean, mineral versus chemical filters, how much to apply and why it beats every anti-ageing cream.
Sunscreen is the highest-return product in any routine. UVB causes burning and most skin cancers; UVA penetrates deeper, drives photo-ageing, pigmentation and loss of elasticity, and passes through window glass. Daily protection prevents damage no serum can reverse.
Reading the Label
SPF measures UVB protection: SPF 30 blocks about 97%, SPF 50 about 98%. The jump matters less than applying enough. PA+ to PA++++ (Asian labelling) and UVA in a circle (EU labelling) indicate UVA protection — always look for one of them; "broad spectrum" alone is a weaker guarantee.
Mineral vs Chemical
Mineral (zinc oxide, titanium dioxide) sits on the surface, scatters and absorbs UV, starts working immediately, and suits sensitive and post-procedure skin. It can leave a white cast on deeper tones. Chemical / organic filters (avobenzone, tinosorb, uvinul) absorb UV and convert it to heat. They are cosmetically elegant, invisible on all skin tones, and modern European and Asian filters are extremely photostable.
Neither is safer than the other for everyday use; the best sunscreen is the one you will reapply.
How Much and How Often
Roughly a quarter-teaspoon for the face and another for the neck — about two finger lengths. Most people use a third of that and get a third of the labelled protection. Reapply every two hours outdoors, after swimming and after towelling.
Sunscreen Under Makeup
Apply as the last skincare step, wait two to three minutes, then foundation. Reapply during the day with a stick, a cushion compact or an SPF powder over makeup. Foundation with SPF 15-20 does not replace a dedicated sunscreen, because you never apply enough of it.
The Payoff
Studies following daily sunscreen users over four years found measurably less photo-ageing than in non-users. No $700 cream matches that result for the price of a $15-30 bottle.
Disclaimer
This content is for informational purposes only and does not constitute investment advice. You are advised to consult a qualified financial advisor before making investment decisions. USD Euro 360 makes reasonable efforts to ensure the accuracy of the information presented but cannot be held responsible for any losses.