UPF is the abbreviation for Ultraviolet Protection Factor.
A UPF 50+ rating is granted to hats that have been proven to block 50% or more of ultraviolet radiation. The hats are tested on a machine called a UV 1000F Ultraviolet Transmittance Analyzer which measures the spectral transmittance of the Squishee® straw or fabric brim. The data is then converted to an Ultraviolet Protection Factor (UPF) used to determine the material’s protective ability.
Eric Javits headwear materials are tested against the standards developed by the American Society for Testing Methods (ASTM) Committee D-13.65 and the American Association for Textile Chemists and Colorists (AATCC) for UV testing and labeling of sun protective clothing and shade devices.
Eric Javits hats, certified with this rating, are labeled as such and guaranteed to deliver an Ultraviolet Protection Factor (UPF) of 50+, the maximum rating given.
Dermatologists recommend wearing hats in conjunction with sunscreens because the active ingredients in sunscreens deactivate after exposure of more than 2 hours to light.