Testing Standards for UV-Protective Fabrics

The Ultraviolet Protection Factor (UPF)-also known as the ultraviolet blocking factor-is a metric indicating a fabric's ability to protect against ultraviolet (UV) radiation. It is defined as the ratio of the average UV radiation incident upon unprotected skin to the UV radiation transmitted through the fabric being tested.

UV Transmittance: Refers to the percentage ratio of the intensity of UV radiation transmitted through a sample to the intensity of UV radiation measured in the absence of a sample.

According to the definition provided in national standards, UPF represents "the ratio of the average effect of UV radiation calculated for unprotected skin to the average effect of UV radiation calculated for skin protected by fabric."

A higher UPF value indicates superior UV protection; however, national standards for textiles cap the highest designated UPF rating at 50+ (meaning UPF > 50). This is because, once the UPF exceeds 50, the residual impact on the human body is considered entirely negligible.

The standard *Evaluation of UV Protection Properties of Textiles* (GB/T 18830), promulgated by the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ), stipulates the following:
A. A product may be designated as an "anti-UV product" *only if* the sample's UPF value exceeds 30 *and* its UVA transmittance is less than 5%. Both of these conditions must be met simultaneously; neither can be omitted. These serve as the definitive criteria for determining whether a product qualifies as an "anti-UV product."
B. Anti-UV products must display the following three pieces of information on their labels:
1. The national standard number: GB/T 18830
2. The specific UPF value
3. The rating: 30+ or ​​50+

Note:
If the measured UPF value exceeds 30 and the UVA transmittance is less than 5%, the product shall be labeled as: 30+.
If the measured UPF value exceeds 50 and the UVA transmittance is less than 5%, the product shall be labeled as: 50+.
The protective performance provided by this product may diminish over time with prolonged use, or when the fabric is stretched or wet.