[Kuuipo]

Don't rely on foundations with SPF for any degree of protection-especially if you drive or walk to work in daylight. Same thing, in 2 hours your SPF protection has degraded and is delivering free radicals below the surface of your skin. A hat is a better option. Mineral makeup is better than the SPF in liquid foundations because its generally zinc, which is photostable.
Broad spectrum only means that it screens out UVA/UVB rays up to 2 hours with some reliability. For reliability, it must be applied generously (slathered on) every 2 hours.