Altered Latitudes is using UPF 50+ UV/Sun Protection Shirts to protect you from harmful UV Rays.
What is UPF?
Ultraviolet Protection Factor (UPF) is a rating system used for apparel. It indicates how effectively fabrics shield skin from ultraviolet (UV) rays. The higher the UPF number, the greater degree of UV protection a garment offers.
UPF is similar to SPF (Sun Protection Factor), the rating system used for sunscreen products. UPF gauges a fabric's effectiveness against both ultraviolet A (UVA) and UVB light. An SPF number pertains only to a sunscreen's effectiveness against UVB rays, the sunburn-causing segment of the ultraviolet spectrum.
What are UPF ratings?
UV-protection claims for clothing were first formalized in the 1990s in Australia, where skin cancer is a widespread concern. Researchers there developed the first fabric testing procedures for UV transmission and created a UPF rating system. Clothing manufacturers have since voluntarily adopted this system.
Basically, a UPF rating of 50 indicates the fabric of a garment will allow only 1/50th (roughly 2%) of available UV radiation to pass through it. A garment rated UPF 25 permits roughly 4% (1/25th) UV transmission.
The higher the number, the better the protection the fabric offers. Any fabric that allows less than 2% UV transmission is simply labeled UPF 50+.
All fabrics in some way impact the transmission of UV radiation. You may read that fabrics "absorb" UV rays, but that wording implies that fabrics somehow soak up UV radiation like a sponge. That's not exactly the case. When ultraviolet radiation and textiles interact, the energy of UV rays is changed. UV radiation is converted to heat, a transformation that renders most rays harmless. Some garments, depending on factors such as construction, dyes and fabric treatments (explained later in this article), do a better job at this than others.