All French dermatologists agree on the fact that during regular days, even more during days spent indoors, SPF has absolutely no use. They also alert on the toxicity of the SPF filters and of the consequences of these filters on our health when applied every day, starting with hormone disruptions, risks of cancer and more.
They recommend to use sunscreen during prolonged exposure when at the beach or at the park: besides protective clothing, sunscreen has to applied in sufficient quantity and replenished every 2 hours or more to be efficient.