Ultraviolet Protection Factor and Sun Protection Factor

When it comes to sun protection, what we commonly hear is SPF or Sun Protection Factor. The words SPF and Sun Protection Factor are easily noticed when you pass through the skincare section. The first to look for when a customer buys a screen.

What is less heard or known is the UPF or Ultraviolet Protection Factor. The UPF is asked when buying sun protection fabrics or tents.

In summary, the SPF (Sun Protection Factor) and UPF (Ultraviolet Protection Factor) are standards used to measure sunburn protection. The SPF system is used to measure the effectiveness of sunscreens while the UPF system is for sun protective fabrics.

Sun Protection Factor

The first evaluation of the protective efficacy of sunscreens was done in 1934 by Friedrich Ellinger. Friedrich Ellinger determined the minimal erythemal dose (MED) for protected and unprotected skin, using both forearms and a mercury lamp. He then proposed a coefficient of protection that decreased in value to the extent that protection increased.

In 1956 when Rudolf Schulze evaluated commercial sunscreens by calculating a protection factor, called the “Schulze Factor”. Rudolf Schulze divided the exposure time to start erythema on sunscreen-protected skin by the time required to start  production of erythema on unprotected skin. Rudolf Schulze used incremental doses of radiation emitted by lamps with a radiation spectrum closer to sunlight.

In 1956 when Rudolf Schulze evaluated commercial sunscreens by calculating a protection factor, called the “Schulze Factor”. Rudolf Schulze divided the exposure time to start erythema on sunscreen-protected skin by the time required to start the production of erythema on unprotected skin. Rudolf Schulze used incremental doses of radiation emitted by lamps with a radiation spectrum closer to sunlight.

Due to the lack of standardization of the Sun Protection Factor method, the numerical values varied considerably, making the system unreliable. It was only in 1978 that the North-American regulatory agency (FDA) proposed the first normalization to determine the Sun Protection Factor.

Ultraviolet Protection Factor

Clothes were used as protection against the sun for thousands of years. Skipping to the modern age, sun-protective clothing was popularized in Australia to adjunct to sunscreen lotions and sunblock creams. Sun protective clothing and UV protective fabrics in Australia then followed lab-tests regulated by ARPANSA. This standard was established in 1996, following the work of an Australian swimwear company.

It was only in 1998 that the British standard was established by the National Radiological Protection Board and the British Standards Institute. The United States standard was formally established in 2001 and used the Australian method as a model. UPF testing is now widely used on clothing for outdoor activities.

Tip for selecting sun protective fabrics

What construction? Densely woven cloth, like denim, canvas, wool, or synthetic fibers is more protective. You can check a fabric’s sun protection by holding it up to the light, if you can see through, UV radiation can easily penetrate the fabric.

Beach Tent "Venus" 2

What color? Dark or bright colors absorb UV rays rather than allowing them to pass through the fabric.

What materials? Unbleached cotton has natural lignins that act as UV absorbers. Shiny polyesters and even lightweight satiny silks reflect radiation. High-tech fabrics treated with chemical UV absorbers or dyes prevent some penetration from UV rays.

One thing fact is certain. Thermalabs' beach tents offers you protection at 30 UPF while on the beach this summer. Grab your protection now.

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