Altitude Increases Sunburn Risk
Source Newsroom: American Academy of Dermatology (AAD)
ALTITUDE INCREASES SUNBURN RISK
SCHAUMBURG, IL (January 13, 1999) -- Skiers, hikers and others enjoying outdoor activities in the mountains have long believed that the amount of time it took them to develop sunburn was shorter than when they were at lower levels. New research confirms that the higher the altitude, the quicker a person will develop sunburn. In fact, the risk gets greater faster with increasing altitude than initially suggested.
A researcher from the Ronald O. Perelman Department of Dermatology at the New York University School of Medicine used a hand-held meter (National Biological Corporation Model 500-C) to measure UV light energy in three locations: Vail, Colorado; Orlando, Florida; and New York, New York. The readings were taken at solar noon in direct sunlight on cloudless days.
"We found that the direct UV-B levels at 8,500 feet in Vail, Colorado, were approximately 60 percent higher than at sea level in New York," said Darrell S. Rigel, MD, the lead author of the study. "In addition, the direct UV-B levels in Vail were the same as those in Orlando, a site nearly 775 miles closer to the equator."
The intensity of the UV-B exposure suggests that a person having an average complexion, with unprotected skin, would burn after only six minutes of sun exposure on a clear day at noon in Vail at 11,000 feet above sea level. The same person would develop sunburn after 25 minutes of noontime exposure in New York or 14 minutes of unprotected noontime exposure in Orlando.
A person's exposure to ultraviolet light, especially UV-B light, is one of the key factors in the development of skin cancer. An estimated 1 million new cases of skin cancer will occur in the United States this year, and, at current rates, 1 in 5 Americans will develop skin cancer during their lifetime.
"The high altitude regions in the U.S. contain areas with some of the fastest population growth in the country," noted Dr. Rigel. "It is vital that those living or visiting these regions recognize the increase in UV exposure at higher altitudes and take extra precautions to prevent sunburn." The research model suggests an approximate 8 percent to 10 percent increase in ultraviolet intensity for each 1,000 feet of elevation across the studied altitudes. UV-B intensity decreases as light moving toward the Earth is scattered, reflected and/or absorbed. The higher the altitude, the more intense the UV-B light exposure can damage unprotected skin.
With the increased exposure to UV-B, the expected annual non-melanoma skin cancer rate for year-round residents at 8,500 feet is estimated to be approximately 115 percent greater than those living at sea level at the same latitude. By comparison, the rate is projected to be 100 percent greater at sea level in Orlando than in New York. Melanoma rates can also be expected to be higher at increasing altitudes.
"The American Academy of Dermatology recommends that everyone wear protective clothing, avoid the strongest mid-day sun and wear sunscreen daily," said Dr. Rigel. "This study shows that this triad of protective measures is increasingly important as a skin cancer prevention measure in high altitude areas -- especially as the population of those areas grows." The American Academy of Dermatology, founded in 1938, is the largest, most influential, and most representative of all dermatologic associations. With a membership over 11,000 dermatologists worldwide, the Academy is committed to: promoting and advancing the science and art of medicine and surgery related to the skin; promoting high standards in clinical practice, education, and research in dermatology; supporting and enhancing patient care; and promoting the public interest relating to dermatology through public education programs.
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