Originally Posted by
MegaTom
As someone that currently lives in a crazy humid climate that is FL, I'd still say that it's flat out wrong. You have to reapply the SPF15 and 30 stuff just as often as the 50 or 100; and with some peoples' skin being more sensitive than others, the higher SPF can indeed make a big difference.
Something most people don't realize, is that most sunscreens are a *sacrificial* chemical.
i.e. the active ingredients are chemicals that are broken down by UV radiation.
And as they break down, they become ineffective.
So you need to reapply regardless of sweating or swimming.
Exceptions are sunscreens containing zinc-oxide or titanium-oxide.
These physically block UV but look white, so people generally don't like the appearance.