What Is the Effect of UV Light on Skin?
Ultraviolet (UV) light comes from many sources. While the sun represents the most common source of UV light that effects humans, artifical sources include halogen lights, tanning booths, black lights and germicidal lamps. Different types of UV light exist in the spectrum, and each type has a different potenail effect on the skin.
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Electromagnetic Spectrum
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The electromagnetic spectrum consists of a wide range of light energy. Radio waves, microwaves, infrared, visible, ultraviolet, X-rays and gamma rays all exist at different wavelengths. Anything outside of the visible spectrum of light is not seen by the naked human eye.
UV Light
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Light in the ultraviolet spectrum exists primarily between the wavelengths of 180 nanometers (nm) to 400 nm. This UV light consists of three main recognized types of light within the UV spectrum: UV-A, UV-B and UV-C. UV-A and UV-B penetrate from the sun to the surface of the earth every day, and comes into contact with skin. UV-C penetrates from the sun to the ozone, where the ozone layer blocks it out. UV-C never comes into contact with skin in nature.
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UV-B Light
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The most dangerous variety of ultraviolet sunlight that reaches the surface of the earth, UV-B, has a wavelength in the range of 290 nm to 320 nm. UV-B radiation can cause double stranded breaks in deoxyribonucleic acid (DNA), which may lead to mutations responsible for uncontrolled cell growth resulting in skin cancer.
UV-A Light
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UV-A light occurs from 320 nm to 400 nm in the electromagnetic spectrum. UV-A light, while much less dangerous than UV-B light, still causes cumulative damage that leads to aging and wrinkling of the skin. UV-A light also penetrates much deeper into the skin that UV-B. Most cancers result from damage to the surface layer of the skin, where UV-B irradiation is prevalent.
Prevention
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According to Skincancer.org, the worst time for seeking sunlight is from 10 a.m. to 4 p.m.. At these hours, the UV radiation from the UV-B part of the spectrum tends to be worst. Sunscreen of greater than SPF 15 is recommended if you plan to spend a lot of time outside. Just because clouds cover the sun, doesn't mean UV rays are not coming into contact with your skin. You should also see a doctor on a regular basis to examine your skin. Skin cancers can start out looking like a common mole, hard to diagnose as cancer to the untrained eye.
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References
Resources
- Photo Credit uv light. image by Harvey Hudson from Fotolia.com
