Choosing Sun-Protective Clothing

Dermatologists have recommended the use of topical sunscreen products for years, but what about sun-protective clothing? Clothing and hats supply a physical barrier that reduces the amount of ultraviolet (UV) radiation that can reach the skin. Current research states that sun-protective clothing is one of the most effective forms of protection against sun damage and skin cancer due to its ability to absorb or block harmful UV radiation.¹ While all clothing provides a level of protection from UV radiation, clothing designed specifically for sun protection is often manufactured in ways that increase the ultraviolet protection factor and reduce the amount of UV radiation that can penetrate the skin. Adequate clothing can protect the skin from harmful UV exposure, but the amount of protection depends on how much of the overall body surface is covered and the quality of the UV protection provided by the fabric.

Ultraviolet Protection Factor (UPF)

Ultraviolet protection factor (UPF) indicates how much UV radiation can penetrate through a fabric and reach the skin.¹ It is also referred to as ultraviolet transmission. UV transmission is an important factor that determines the level of UV protection of textiles. A fabric with a UPF 50 rating blocks 98 percent of the sun’s rays, allowing only two percent of the harmful rays (1/50th) to penetrate through the fabric.¹ The use of sun-protective clothing significantly reduces exposure to UV radiation and therefore reduces the risk of premature skin aging and the development of skin cancer. The higher the UPF, the less light that can reach the skin. A fabric must have a UPF of at least 30 in order to qualify for the Skin Cancer Foundation’s Seal of Recommendation.

UPF vs. SPF

SPF (Sun Protection Factor) and UPF (Ultraviolet Protection Factor) are standards used to measure sunburn protection. UPF is used to measure the amount of UV radiation that can penetrate through fabric and reach the skin while SPF is used to measure the amount of time a person can be exposed to the sun before the UVB radiation is absorbed by the skin and induces redness.² For example, if you normally burn after 10 minutes without sunscreen, an SPF 15-rated sunscreen will prolong the time by a factor of 15 (10*15 = 150 minutes) when used correctly. A noteworthy distinction between UPF and SPF is that UPF measures both UVB and UVA rays while SPF only measures UVB rays.

Garment Protection Factor (GPF)

Industry standards reflect the need to protect the skin by covering a considerable proportion of the exposed body surface area (BSA) and by reducing UVR-transmission through fabric. The garment protection factor (GPF) is a new index for rating sun-protective clothing that incorporates the body surface area (BSA) covered and the ultraviolet protection factor (UPF) of the fabric from which it’s made to determine how effective a garment is at reducing harmful sun-exposure.⁴ The garment protection factor increases as the covered body surface area increases. Adoption of the rating scheme was intended to provide consumers with adequate information to make an informed choice in sun-protective attire and to incentivize manufacturers to design sun-protective clothing that exceeds the minimum standards.

Factors That Influence Sun Protection

All clothes can block UV radiation, but they do so at varying degrees. Sun protection clothing is specially designed to block UVA/UVB radiation by leveraging various factors, such as fabric type, construction, color, weight, and thickness. A clothing’s porosity, described as a fabric’s openness, cover factor, and tightness of the weave, is one of the most important factors that influence the transmission of ultraviolet radiation through fabric. Knitted fabrics have more space between the collection of yarns compared to woven fabrics, resulting in higher UV transmission and less UV protection in knitted fabrics. It is challenging to compare the UPF between different materials due to the production steps that may influence the UPF rating. On average, cotton and rayon have the least UV absorbing capacity (UPF <15) while polyester has the highest natural ability to absorb UV radiation. Nylon, silk, and wool are in between these two groups.⁵

In addition, thicker, darker-colored clothing is more effective against UV radiation compared to thin, white, or light-colored clothing. Black fabric surprisingly does not have the highest UPF, with a typical UPF 30 rating. Colored fabric has better UV protection than white fabrics, and darker colors have better UV protection than lighter colors. Several factors can alter the UV protective capabilities of a garment including stretch, moisture, and fabric degradation caused by normal use or laundering.¹

Factors that Enhance UPF Efficacy

• Coverage: The more skin the clothing covers, the better the protection. Whenever possible, choose long-sleeved shirts and long pants or skirts.
• Construction: UPF increases with fabric density and thickness.⁴ Dense, tightly woven fabrics minimize the amount of UV light that can pass through. Thicker fabrics, like denim, reduce UV transmission better than thinner fabrics. Heavier fabrics are typically better at blocking UV rays compared to lighter fabrics.
• Color: Darker fabrics absorb more UV rays compared to lighter fabrics.¹ Within the same color, more vibrant hues are more effective at reducing UV transmission compared to paler hues.
• Chemicals: Treatments, such as chemicals and dyes, that are effective at absorbing UV light can be added to enhance the UPF of the fabric. Fabrics that are engineered for UV protection often use a high concentration of premium dyes that disrupt UV light using conjugated molecules.¹ Laundry additives, such as brightening agents and UV-blocking additives, are often used to increase a garment’s UPF rating.⁵
• Fabric material: Shiny polyesters and lightweight, satiny silks can be highly protective because they can reflect UV radiation.¹ Nylon and wool are also known to disrupt UV light well. Cotton, rayon, viscose, flax, and hemp are not as effective at blocking UV radiation unless treated with additives. Unbleached cotton has natural lignins that act as UV absorbers, resulting in a proposed increase of UPF compared to bleached cotton.¹

Factors that Reduce UPF Efficacy

• Moisture: Increased moisture can cause a drastic reduction in a fabric's UPF rating by as much as 50 percent for most fabrics.⁴ A white T-shirt supplies only moderate sun protection with a UPF of about 7. When that T-shirt gets wet, it supplies a UPF of only 3.
• Fading: A fabric becomes less effective at blocking UV light as it becomes worn and faded.⁴ In addition to the act of wearing clothes, sun exposure, chemical disinfectants, antiperspirants, and the secretion of bodily fluids combined with bacteria can lead to gradual and significant erosion of the fabric.⁵
• Fabric stretch: Clothing that stretches may have less UV protection compared to clothing that does not stretch.⁶ It is important to select clothing with a loose fit to reduce the amount of stretch imposed on the garment.
• Laundering: UPF can diminish during laundering for clothing that relies on finishes for its UPF rating.⁴ UPF should remain unchanged for clothing with inherent properties that supply a strong UPF rating. Shrinkage due to laundering can theoretically increase the UPF of a garment because shrinking gives the garment a tighter weave.⁴ Fabric brighteners are suspected to enhance the ultraviolet protection factor. However, further research is required to determine if a given detergent will enhance a garment’s UPF rating.

How to Choose the Best Sun Protection Clothing

There is a growing demand for clothing that is not only stylish but also supplies protection from the harmful effects of ultraviolet radiation. Yes, clothing shields you from the sun, but not all fabrics and colors supply equal protection. Sun protection clothing is specially designed to prevent harmful UV radiation from penetrating the skin. Manufacturers focus on supplying extended coverage, ventilation, and quick-drying fabrics. When shopping for apparel that can effectively shield the skin from harmful rays, keep the following factors in mind.

Who Should Wear UPF Clothing?

While everyone can benefit from the use of UPF clothing, it can be especially beneficial for:

• People sensitive to the sun: People with fair skin who burn easily are more vulnerable to UV rays.
• People allergic to sunscreen: Some ingredients, such as fragrances and oxybenzone, may cause an allergic reaction that looks like a heat rash or allergic dermatitis and presents with a red, often itchy, rash. Other symptoms can include swelling, blisters, bleeding, scaling, and pain.⁸
• Infants and children: Sunscreen is not recommended for infants.⁹ Children under the age of six months have a higher risk of experiencing sunscreen side effects, such as a rash, when compared to adults. Instead, the FDA recommends keeping infants out of the sun during peak sun hours and using protective clothing when they must be in the sun.⁹ Children have thinner, more sensitive skin and require adequate protection to prevent damage from occurring at an early age that can increase their risk of developing skin cancer later in life.
• People at high elevations or on snow or water: Sun intensity is greater in each of these environments.¹⁰
• People taking medications: Sun sensitivity can be increased by a variety of drugs, including acne treatments, antihistamines, antibiotics, certain anti-inflammatories, and herbal supplements.¹¹

Although sun-protective clothing can effectively be used to prevent damaging UV radiation from reaching the skin, it should not be used as the sole method of sun protection. Sunscreen and sun avoidance practices are an important part of the sun protection strategy and should be used alongside sun-protective clothing.

Practical Tips

• Check a fabric’s density and sun protection capability by holding it up to the light. If you can see through the fabric, UV radiation can easily penetrate the fabric and reach your skin.
• Always consider the garment’s UPF and GPF rating, if available, when evaluating its true UV protection level.
• If buying new sun-protective clothing is not a part of your current budget, consider washing your clothes with a laundry detergent that has a UV-blocking additive. It can give your clothes a UPF of 30 and last for approximately 20 washes.

Key Takeaways

• Clothing and hats are among the simplest and most effective ways to guard your skin from the sun’s harmful rays. They supply a physical block between your skin and the sunlight that can be enhanced through the addition of chemicals and additives.
• Clothing constructed of tightly woven and darkly colored fabric that supplies extended body coverage will yield the most protection from UV radiation.
• UPF-rated clothing alone will not fully protect you. Total UV protection requires a multifaceted approach that includes wearing UV-protective clothing, sunglasses, shoes, and wide-brimmed hats, seeking shade whenever possible, and applying sunscreen with a high SPF rating to all exposed areas of skin.