UPF SunShirt

UPF and SPF Explained

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Why do we specifically need sun protective clothing?

Most people think that if they are wearing any type of clothing that their skin is protected from UV (ultraviolet) exposure.  To some extent, this can be true but the question is really how much protection is your clothing offering?


The studies available have shown that the average UPF (ultraviolet protection factor) of a white T-shirt is around 5. This is not even close to the recommended minimum UPF of 20. We often apply sunscreen to exposed areas of skin and do not tend to consider the need to protect under our clothing. Although daily chronic UV may not show itself as a true sunburn, cellular damage is occurring with chronic sun exposure.

How can I tell if my clothing protects me from UV exposure?

To be able to tell if your clothing is protecting you from UV it needs to disclose the testing it has undergone for UV protection.  Skincare products use a rating scale called “SPF” or sun protection factor to give a sense of protection the product offers.  Most people are familiar with this rating, in spite of how confusing it may be.  Clothing is rated by UPF, ultraviolet protection factor.  This rating scale and what it indicates are a little different.

Let’s break this down, tell me the difference between UPF and SPF.

SPF stands for sun protection factor.  This is an FDA-regulated claim where companies test skincare products -lotions, moisturizers, creams, and sprays- for how much UV protection is offered.  More specifically, SPF tells us how much a product is protecting our skin from experiencing a sunburn from UVB exposure.  It does not tell us how much UVA is being blocked or absorbed by the product.  

UPF stands for ultraviolet protection factor.  Clothing items and textiles can be tested for how much UV is blocked by the textile.  There are specific standardized tests that are performed that indicate how much UV is blocked initially AND sustained through 40 machine wash/dry cycles.  Clothing is tested before and after the 40 cycles. Why? The testing is trying to simulate normal wear and tear that a garment may experience.  The other big difference is that UPF tells us how much UVA and UVB are blocked by the textile.  This is helpful because both types of UV can be responsible for UV damage to our skin over time.

SPF (Sun Protection Factor)

UPF (Ultraviolet Protection Factor)

Products Tested

Skincare products

Clothing, textiles

Types of UV tested



UV Protection Sustained

Reapply product every 2 hours

Sustained UV protection 

How does clothing protect our skin from UV exposure?

Many companies add chemical finishes to clothing to increase the UPF. These chemical finishes only have a handful of studies evaluating safety.  Believe it or not - they have demonstrated that our skin has some absorption of these finishes.  These finishes also potentially wash out of clothing and end up in our water supply.

Clothing has been recommended as another way to protect our skin by the American Academy of Pediatrics, however very few studies have been done to really speak to its effectiveness AND even fewer studies on the safety of chemical finishes companies add to clothing to make them more effective against the sun.

The other way to achieve UV protection from clothing is to create textiles with quality construction and weaves that effectively block UV based on how the fabric is created.  There is no need to add chemical finishes to add UV protection if there is a focus on textile construction. 

Why does it matter if chemical finishes are added to textiles?

The challenge with chemical finishes and clothing is the lack of human and environmental studies available on the impact on our health and environment.  However, we do have some history with chemical finishes and clothing to fall back on.  This goes back to pajamas and flame retardants.



There is a long history behind flame retardants and pajamas.  In 1953, the Flammable Fabrics Act (FFA) was passed to regulate highly flammable fabrics such as children’s pajamas after several incidences from various textiles used in children's pajamas in the 1940s that resulted in tragic deaths.  This act was amended by 1967 to include upholstery, carpets, and certain textiles.  This essentially required the textiles used to pass flammability standards.  This often meant that flame retardants were actually added to the textiles to make them less flammable.

In the 1970s, brominated and chlorinated flame retardants used in these textiles were identified as mutagenic to DNA and carcinogenic.  These were replaced with newer brominated and chlorinated flame retardants.  These newer options have been found to persist and accumulate in the environment, house dust, and in people and wildlife.   There is data that is accumulating showing that these compounds can also be carcinogenic, mutagenic, neurotoxic, and endocrine-disrupting. 


The FFA is still in effect.  Children’s pajamas for ages 9 months to 14 years of age must be made of flame-resistant fabrics if they fit loosely.  Because of the studies demonstrating the risks with the chemical finishes, companies had to find a way to bypass the need for using these chemicals.

There are two ways to avoid pajamas made of textiles treated with flame retardants. 

One way to bypass the need to use these flame retardants is to ensure the fit is snug to avoid excess fabric placing the garment at higher risk for flammability. This prevents loose hanging fabric at risk for exposure to flames as well as reduces the oxygen build-up between the skin and the fabric to reduce the overall flammability.  Remember, these laws were passed at a time that smoke detectors and other fire safety measures were not widely available.  In order to determine if your child’s pajamas contain these flame retardants look for a yellow label that reads as follows: “For child’s safety, garments should fit snugly. These garments are not flame resistant. Loose-fitting garments are more likely to catch fire.”


Another method to avoid flame retardants is for pajamas to be made of 100% polyester. Polyester is inherently flame resistant.   The tags on these garments will state “flame resistant”. 

Although these endocrine and mutagenic flame retardants could potentially still be found in some pajamas, they are rarely used by manufacturers as many have opted to ensure a snug fit or use polyester.  

As to whether these chemicals from pajamas can be contributing to the incidence of juvenile diabetes, although possible theoretically if a parent is choosing pajamas that have not avoided it, the more likely exposure to flame retardants if they are indeed linked to juvenile diabetes is through upholstery and the environment given the widespread use of the products.


This is more of a reminder that the story of chemicals and textiles is evolving. It took over 20 years for the chemicals used as flame retardants to be identified as mutagenic, carcinogenic, and endocrine-disrupting.  This means that an entire generation wore these garments routinely with unclear impact on their health and the environment.  

This is one more reason to reduce or limit unnecessary exposure to these products.

does sunscreen expire

How can I tell if there are chemical finishes in my clothes?

The short answer is you don’t know unless the company tells you.  There is no disclosure required on labels for these chemicals.  If a company does not use chemical finishes there is a good chance that they will highlight this in their marketing materials.  Look for companies that care enough to demonstrate an understanding of these potential risks and disclose whether or not they use textiles treated with UV chemical finishes.

Based on our research of individual brands and what is published on their websites, here is an example of the information we have compiled...


 Brand Added UV treatment  Claim on site
AmberNoon None No UV Finishes added
AmberNoon II by Dr Erum Ilyas None No UV Finishes added
Coolibar Yes "...and additions of the best active ingredients found in sunscreens, millions of the sun-bouncing minerals, titanium dioxide and zinc oxide infused at the fiber or fabric level." 


what is spf

Can you break down the rating scales for UPF and SPF?

Here is the UPF system:



% UVA and UVB blocked



93.3% to 95.9% blocked


Very Good

96.0% to 97.4% blocked





Here is the SPF system:


% UVB blocked or absorbed by the product












It is worth noting the similarities between the rating and percentage of UV blocked or absorbed.  The main difference is that the SPF does not test for UVA exposure risks.



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