What is an SPF rating?
Sun Protection Factor (SPF) refers to the U.S. Food and Drug Administration’s (FDA) approved techniques to assess the efficacy of a sunscreen in the Ultraviolet B (UVB) portion of the spectrum. An SPF rating does not measure Ultraviolet A (UVA) protection. The textbook definition of SPF is the ratio of the time of ultraviolet radiation (UVR) exposure necessary to produce minimally detectable erythema in sunscreen-protected skin to that time required to produce the erythema in unprotected skin. The SPF number gives you some idea of how long you can stay in the sun without burning. For example, if you normally burn in 10 minutes without sunscreen and you’ve applied a liberal dose of a sunscreen with an SPF number of 15, you should be protected from sunburn for 150 minutes. A very water-resistant rating is given if that same sunscreen still tests at the same SPF after being applied to human subjects and submerged in moving water for four 20-minute immersions. Our powders achieved an SPF 2
