When skin burns on the outside, it becomes damaged on the inside. “Sun exposure is cumulative and the bulk of it happens during the first 18 years of life,” says Lafayette, LA, plastic surgeon Darrell L. Henderson, MD. While awareness about the dangers of the sun has increased, there is also a rise in skin cancers. “I’m seeing more sun-damaged skin and premature aging than ever before. Part of it is due to using tanning beds, as well as childhood sunburns the damage is surfacing now,” says New York dermatologist Whitney Bowe, MD.
The majority of ultraviolet light that reaches earth’s surface comes in the form of long-wave ultraviolet or UVA rays. UVA rays penetrate skin deeper than UVB rays and cause premature aging, wrinkles and skin cancers. They also affect collagen through oxidative stress when free radicals form. They aren’t as strong as UVB rays, but they are more dominant, so more of us are exposed to them regularly. Shorter in length but still damaging, UVB rays burn skin and cause harm to the more superficial layers. UVB rays also cause direct damage to the skin’s DNA, potentially leading to skin cancers.
The Sun-Damage Cycle
- UV Ray Absorption – Skin absorbs both UVA (deep within the skin) and UVB rays (on the surface)
- Pigment is created – The UVA rays trigger a change in melanocyte activity. “Melanin granules close to the surface of the skin are oxidized by UVA radiation and become darker,” says Brooklyn, NY, dermatologist Tatiana Khrom, MD. “Melanocytes deep in the epidermis are stimulated and produce new melanin granules and transfer to the upper layers of skin, forming an ‘umbrella’ to protect the DNA from UV radiation.”
- DNA becomes damaged – The more skin is exposed to UV rays, the less protection DNA has, which leads to damage. “DNA is overwhelmed over time and the accumulation of free radicals and DNA breaks lead to errors in cell division, which is what can cause skin cancer,” says Dr. Khrom.
Inside tip: According to the AAD, the best type of sunscreen is that of SPF 30 or higher.
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