UVa/UVb Facts & Information

Not all shade is equally protective.

Think you’re safe from UV rays under your sunshade?

Think again… Up to 1/3 of cancer causing rays can reach your skin while you are sitting in the shade. ezShade is the only portable shade curtain that helps block reflected rays and doubles your shade area.

Know the Facts: While shade is a potentially valuable means of protection from the damaging effects of the sun’s ultraviolet (UV) rays, not all shade is equally protective. People can spend long hours in the shade while still receiving quite a lot of sun exposure and risking skin damage. This is because UVB rays, often considered the most harmful part of sunlight, can reach the skin indirectly.
Indirect or diffuse UV light is radiation that has been scattered by the clouds and other elements in the atmosphere, and/or bounced back from UV-reflective surfaces like dry sand or concrete. In fact, a large percentage of the UV light we receive while sitting under a tree or an umbrella is indirect.


Unless they are very large, umbrellas provide relatively little UV protection. Their UPFs can be up to 50+ (UPF, the ultraviolet protection factor, measures protection from UV radiation in fabrics. A UPF of 30 indicates that just 1/30th of the sun’s UV radiation can reach the skin), but no matter how high the fabric’s SPF or UPF, the amount of UV present beneath an umbrella can be up to 84 percent of that in sun (1) depending on the levels of indirect UV; the amount of indirect UV is proportionate to the amount of open sky visible from the shade (2). Therefore, a single umbrella on a sandy beach by the sea provides limited sun protection because so much UV is reflected under the umbrella from the surfaces of the sand, water and sky(3).

The difference between a typical beach umbrella and a UV umbrella from EzShade.

Other Shade Structures

Shade structures such as canopies vary widely in the amount of protection provided.Since levels of indirect UV can still be high beneath these shade structures, many have real SPFs of only around 3-6 (4). In a recent study of 29 shade structures in New Zealand primary schools, only six had SPFs of 15 or greater, the minimum acceptable amount recommended for outdoor activities (5). This was alarming, given the importance of protecting children against UV and the strong evidence that excessive sun exposure during childhood significantly increases the risk of developing skin cancer later in life.

UV Facts


The amount of UV protection provided by a structure is also contingent upon the angle of the sun and the degree of cloud cover. Shade structures with side-on walls or other side protection provide the greatest shelter from the sun’s rays(6). Research done by: Catherine M. Olsen, PhD; Peter G. Parsons, PhD; Adele C. Green, MD, PhD. Article reprinted in part. See the full article.

  • Both UVA and UVB play an important role in conditions such as premature skin aging, eye damage (including cataracts), and skin cancers. They also suppress the immune system (7).
  • Skin cancer is the most common form of cancer in the United States. One in five Americans will develop skin cancer in the course of a lifetime (8).
  • Melanoma is the most common form of cancer for young adults 25-29 years old and the second most common form of cancer for young people 15-29 years old (9).
  • About 65 percent of melanoma cases can be attributed to ultraviolet (UV) radiation from the sun (10).
  • About 90 percent of nonmelanoma skin cancers are associated with exposure to ultraviolet (UV) radiation from the sun (11).
  • Up to 90 percent of the visible changes commonly attributed to aging are caused by the sun (12).
  • A person’s risk for melanoma doubles if he or she has had more than five sunburns at any age (13).
  • Incidence of melanoma continues to rise at a rate faster than that of any of the seven most common cancers (14).
  • One or more blistering sunburns in childhood or adolescence more than double a person’s chances of developing melanoma later in life (15).
  • While melanoma is uncommon in African Americans, Latinos, and Asians, it is frequently fatal for these populations (16).
  • Children under 6 months should not be exposed to the sun.

Best Practices as Recommended by
the Skin Cancer Foundation:

  • Seek the shade, especially between 10 AM and 4 PM.
  • Do not burn.
  • Avoid tanning and UV tanning booths.
  • Cover up with clothing, including a broad-brimmed hat and UV-blocking sunglasses.
  • Use a broad spectrum (UVA/UVB) sunscreen with an SPF of 15 or higher every day. For extended outdoor activity, use a water-resistant, broad spectrum (UVA/UVB) sunscreen with an SPF of 30 or higher.
  • Apply 1 ounce (2 tablespoons) of sunscreen to your entire body 30 minutes before going outside. Reapply every two hours or immediately after swimming or excessive sweating.
  • Keep newborns out of the sun. Sunscreens should be used on babies over the age of six months.
  • Examine your skin head-to-toe every month.
  • See your physician every year for a professional skin exam.

  1. Turnbull DJ, Parisi AV. Spectral UV in public shade settings. J Photochem Photobiol B 2003; 69(1):13-9.
  2. G ies P, Mackay C. Measurements of the solar UVR protection provided by shade structures in New Zealand primary schools. Photochem Photobiol 2004; 80(2):334-9.
  3. Moise AF, Aynsley R. Ambient ultraviolet radiation levels in public shade settings. Int J Biometeorol 1999; 43(3):128-38.
  4. Parsons PG, Neale R, Wolski P, Green A. The shady side of solar protection. Med J Aust 1998; 168(7):327-30.
  5. G ies P, Mackay C. Measurements of the solar UVR protection provided by shade structures in New Zealand primary schools. Photochem Photobiol 2004; 80(2):334-9.
  6. Turnbull DJ, Parisi AV. Increasing the ultraviolet protection provided by shade structures. J Photochem Photobiol 2005; 78(1):61-7; Turnbull DJ, Parisi AV. Effective shade structures. Med J Aust 2006; 184(1):13-5.
  7. Rogers, HW, Weinstock, MA, Harris, AR, et al. Incidence estimate of nonmelanoma skin cancer in the United States, 2006. Arch Dermatol 2010; 146(3):283-287.
  8. Robinson, JK. Sun exposure, sun protection, and vitamin D. JAMA 2005; 294:1541-43.
  9. Bleyer A, O’Leary M, Barr R, Ries LAG (eds): Cancer epidemiology in older adolescents and young adults 15 to 29 years of age, including SEER incidence and survival: 1975-2000. Bethesda, MD: National Cancer Institute; 2006.
  10. Armstrong BK, Kricker A. How much melanoma is caused by sun exposure? Mel Res 1993 December 3(6):395-401.
  11. Pleasance ED, Cheetham RK, Stephens PJ, et al. A comprehensive catalogue of somatic mutations from a human cancer genome. Nature; 2009; 463:191-196.
  12. U.S. Environmental Protection Agency. Health effects of overexposure to the sun. Link. Updated July 1, 2010. Accessed January 25, 2011.
  13. Pfahlberg A, Kolmel KF, Gefeller O. Timing of excessive ultraviolet radiation and melanoma: epidemiology does not support the existence of a critical period of high susceptibility to solar ultraviolet radiation-induced melanoma. Brit J Dermatol March 2001; 144:3:471.
  14. Ries LAG, Melbert D, Krapcho M, Stinchcomb DG, Howlader N, Horner MJ, et al. (eds). SEER cancer statistics review, 1945-2005. Bethesda, MD: National Cancer Institute; Link. Accessed January 24, 2010. 23. Armstrong BK, Kricker A. How much melanoma is caused by sun exposure? Mel Res 1993 December 3(6):395-401.
  15. Lew RA, Sober AJ, Cook N, Marvell R, Fitzpatrick TB. Sun exposure habits in patients with cutaneous melanoma: a case study. J Dermatol Surg Onc 1983; 12:981-6.
  16. Cress RD, Holly EA. Incidence of cutaneous melanoma among non-Hispanic whites, Hispanics, Asians, and blacks: an analysis of California cancer registry data, 1988-93. Cancer Causes Control 1997; 8:246-52.