SPF is a measure mainly linked to UVB, the part of sunlight that is associated with visible sunburn. When used correctly, a higher SPF gives more headroom before that visible effect appears, but it is not a guarantee that you can stay out all day. This Biosun cream is designed to help shield the skin from both UVA and UVB rays: UVA penetrates deeper and is associated with long-term changes such as loss of elasticity and uneven-looking skin, while UVB is more closely connected to sunburn.
Cloudy weather does not mean UV radiation disappears. UV rays pass through clouds, and reflected sunlight from water, sand or snow can also increase exposure. Therefore, on a bright but overcast day, use the same generous layer and reapply it as often as you would in full sun.
This cream can be used beyond beach holidays. It suits walks, gardening, sports, travel and other outdoor time in bright weather. The waterproof base makes it practical when you are active and perspiring, but water and sweat still reduce the layer, so reapply after swimming, towelling off or heavy sweating.