SPF 50 reduces the dose of UVB that the skin can receive before a sunburn by 50 times. But it does not prevent UV rays from entering the skin.
No sunscreen product can completely stop UV rays and the build-up of melanin causing tanning. To choose the right SPF 50 sun protection, the editorial team recommends light mists 50, guaranteed to have zero white marks but effective as long as you apply them every hour. Madame Figaro's wishlist: Ideal Soleil Fresh Face Mist SPF50, Vichy ; Photoderm MAX SPF 500 + sun mist, Bioderma.