What is the sun protection factor?

A measure of the effectiveness of sunscreens is the sun protection factor (SPF). Multiply it by the skin time-dependent self-protection (see table above) with an SPF of the product used, you get the time you spend in the sun may, without a sunburn to get.
The sun protection factor is therefore a factor to which the time to onset of a rash may be extended. The SPF refers only to UVB radiation. In relation to UVA means "according to Australian standard" that at least 90 percent of UVA rays are filtered out.