UV Protection Factor or "UPF"
The Ultraviolet Protection Factor (UPF) rating system measures the UV protection provided by fabric. It is very similar to the SPF rating system used for sunscreens.
A garment with a UPF of 50 only allows 1/50th of the UV radiation falling on the surface of the garment to pass through it. In other words, it blocks 49/50ths or 98% of the UV radiation.
Here are details of the specific test standards.
American Association of Textile Chemists and Colorists (AATCC) Test Method 183 specifies the protocol for conducting a UV transmittance test;
American Society for Testing and Materials (ASTM) D 6544 describes the methods used for evaluation of a fabric's life cycle UV protection;
American Society for Testing and Materials D 6603 provides guidelines for labeling sun protective clothing.
The Need for UV Testing
Certification of UV protection levels is needed as most regular summer clothing rates below a SPF 30 sunscreen in terms of UV protection. For example, Gambichler et al published a comprehensive analysis of regular Summer clothing in BioMed Central in 2001. They examined the level of UV protection provided by 236 different articles of clothing and found that fewer than half the fabrics provided as much protection as a SPF 30 sunscreen. They concluded it was difficult for sun-aware consumers to choose the "right" garments unless they were tested and labeled in accordance with appropriate standards.
In Australia, both sunscreens and sun protective garments are regulated by Federal agencies. The program for sun protective garments is administered by an agency named ARPANSA - an agency similar to the EPA. ARPANSA developed Australian/New Zealand Standard 4399 which is the original globally recognized standard for sun protective clothing. In the US, while the FDA regulates sunscreens, there is presently no Federal program for sun protective garments. However, there are AATCC and ASTM standards described above that manufacturers may follow on a voluntary basis.
Factors Affecting Fabric UV Protection Levels
There are a number of factors that affect the level of ultraviolet protection provided by a fabric and the UPF rating. In order of importance these are: weave (tighter is better), color (darker is better), weight (also called mass or cover factor - heavier is better), stretch (less is better) and wetness (dry is better). The other major factor that affects protection is the addition of chemicals such as UV absorbers or UV diffusers during the manufacturing process. Many factors that make a garment comfortable also make it less protective. The major design challenge for sun protective clothing is how to combine comfort, style and protection in the one garment.
Most summer clothing exposes large amounts of skin to the sun. A major goal for all Coolibar's UV protective clothing and UV protective swimwear designs is to cover as much skin as possible while still making the garment cool and comfortable to wear. Our designs use hidden ventilation and specialized moisture managing UPF 50+ rated fabrics to achieve these dual goals of comfort and maximum skin coverage.
