Sun Care

UVA and Blue Light in the Shade

Some forms of ultraviolet light and blue light can't be escaped in the shade

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Exposure to ultraviolet (UV) radiation puts people at greater risk for skin cancer. Sunlight is the main source of UV rays and there are steps we can take to protect our skin from harm. One popular strategy is to seek shade, but does being in the shade exempt us from wearing sunscreen? The answer is NO! Although shade is a potentially valuable means of protection, not all shade is equally protective, and the amount of protection offered by shade is significantly less than what most of us would think.[1]

 

The Main Types of Light Rays Causing Skin Damage

  • UVA Rays are part of the non-visible light spectrum with wavelengths between 315-400nm. These rays age skin cells and can damage their DNA. UVA rays are linked to long-term skin damage such as wrinkles, but also play a role in the development of some skin cancers. UVA is the most abundant and comprises 95% of the UV light that reaches the earth’s surface (i.e. human skin). UVA makes up the majority of indirect UV light that can reach the shade.
  • UVB Rays are also part of the non-visible light spectrum with wavelengths between 280-315nm. Although slightly higher in energy, most of it is filtered out in the Earth’s atmosphere. They can damage skin cells’ DNA directly and is thought to cause most skin cancers. UVB rays are also the main rays that cause sunburns.
  • Blue Light is part of the visible light spectrum and has a wavelength between 400-490nm. It is categorized as high-energy visible light. Excessive high energy visible light exposure can cause skin aging, pigmentation, and is also damaging to the eyes. 

*Cautionary Note: It is important to use “Broad Spectrum” sunscreen products with an SPF of 30 or higher to protect yourself from both UVA and UVB rays.

 

Harmful Rays Still Hit Your Skin In The Shade

UV rays bounce off objects such as the ground, sand, water, and sides of buildings. Although shade protects you from some of the direct rays from the sun, it does not successfully block scattered or diffused UV rays.[2] Despite the large size of our beach umbrellas, harmful rays still hit our skin from the side and bounce up from below.

 

Different Shade Protections

Hats

Skins cancers occur more often on the head compared to other areas of the body. The face (especially the nose), and ears are commonly affected areas. Although hats are not always considered the “trendy” accessory or are sometimes uncomfortable, wearing a hat is one of the simplest methods to protect your skin from diseases, sunspots, and wrinkles.[3] The best hats to wear are those with broad-brims of at least three inches to ensure face and neck protection. Broad-brimmed hats are approximately equivalent to SPF 5. Ultraviolet Protection Factor (UPF) of hats of 15+ provide even better protection compared to hats made from non-treated fabric. Baseball-style caps offer protection for the face but do not effectively protect the neck area. Therefore, broad-spectrum sun blocks should be used in addition to hats.

Umbrellas

Umbrellas are a great option for UV protection, but there are some limitations. UV rays are small and some UV may penetrate between fabric fibers. The Ultraviolet Protection Factor (UPF) of umbrellas range up to 50+; however, no matter how high the fabric’s SPF or UPF is, the amount of UV present under the umbrella can be up to 84 percent of that in the sun depending on the levels of indirect UV that can come in from around the shade. For a typical umbrella, the true SPF value is approximately between 10 -15 when used in midday sunlight, when the sun is the most intense.[4] Therefore, umbrellas are effective at blocking midday sunlight. However, they are not as effective in blocking UV earlier in the morning or late in the day when the UV rays are more diffuse in the atmosphere. Umbrellas are not likely to protect much against visible blue light. 

Trees

The cooling effect provided by trees is inviting on a hot day, however many factors determine how much sun protection is actually offered.[5] Trees with large and dense foliage provide better protection than those with sparse branches. It is best to choose a tree that is surrounded by other trees or buildings to better block out the sun.

Other shade structures

Roofed areas, tents, and canopies vary in the amount of protection that they provide. These structures provide the approximately the equivalent of SPF 3-6. This is because of the high levels of indirect UVA beneath the structures.[6] When looking for shade structures, those with side-on walls and near other trees and buildings provide the best protection.

 

Additional Considerations

If you’re solely relying on your umbrella to protect yourself from UV and blue light, it’s time to take some additional precautions. Although shade provides protection against direct rays, scattered and indirect rays still reach you from all directions.

If we truly want to protect our skin health, we must practice multiple sun-protecting strategies. Seeking shade is better than being without; however, using sunscreen, protective clothing, and avoiding peak sun hours is the effective way to save your skin.

For further reading on how to protect your skin in the sun, click on the article links below:

Ultraviolet Protection Factor Clothing

What You Should Know About Sunscreens, Clothing and Tanning

Does Chlorine Break Down Sunscreen?

Eat These Ten Power Foods to Protect the Skin From Sun Damage

* This Website is for general skin beauty, wellness, and health information only. This Website is not to be used as a substitute for medical advice, diagnosis or treatment of any health condition or problem. The information provided on this Website should never be used to disregard, delay, or refuse treatment or advice from a physician or a qualified health provider.

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References

  1. Dobbinson S, Niven P, Buller D, et al. Comparing Handheld Meters and Electronic Dosimeters for Measuring Ultraviolet Levels under Shade and in the Sun. Photochem Photobiol.2016;92(1):208-214; PMID: 26575187 Link to research.
  2. Ou-Yang H, Jiang LI, Meyer K, et al. Sun Protection by Beach Umbrella vs Sunscreen With a High Sun Protection Factor: A Randomized Clinical Trial. JAMA Dermatol.2017;153(3):304-308; PMID: 28114650 Link to research.
  3. Yockey RA, Nabors LA, Oluwoye O, et al. College Students' Perceptions of Worry and Parent Beliefs: Associations with Behaviors to Prevent Sun Exposure. J Skin Cancer.2017;2017:4985702; PMID: 28804653 Link to research.
  4. Ou-Yang H, Shyr T. Sun protection by umbrellas and walls. Photochem Photobiol Sci.2017;16(10):1537-1545; PMID: 28850147 Link to research.
  5. Turnbull DJ, Parisi AV. Spectral UV in public shade settings. J Photochem Photobiol B.2003;69(1):13-19; PMID: 12547492 Link to research.
  6. Buller DB, Dobbinson S, English DR, et al. Rationale, design, and baseline data of a cross-national randomized trial on the effect of built shade in public parks for sun protection. Contemp Clin Trials.2017;55:47-55; PMID: 28185996 Link to research.