Olay Articles

The sun gives energy in the form of light waves of different lengths and intensity. The sunlight we see is called visible light. Ultraviolet radiation (UVR) is located just above visible light. UVR is divided into different energy levels from shortest to longest wavelengths: UVC, UVB and UVA.

UVC: The UVC rays have the shortest wavelength, the most energy and fortunately do not penetrate the atmosphere.

UVB: The UVB rays are the most potent rays that reach the earth. UVB rays cause sunburn (think B=Burning Rays) and can also lead to the development of skin cancers. SPF (sun protection factor) ratings measure a product's ability to block UVB rays.

UVA: The UVA rays, while having less energy, penetrate deepest into the skin. These rays cause aging (Think A=Aging). It is the least associated with skin cancer, but if delivered in high dosages can cause skin cancer, allergic and non-allergic sun-induced eruptions, darkening and pigmentation of the skin, and acceleration of the aging process. After chronic, long-term exposure, the skin may appear dry, scaly, spotted, wrinkled and leathery.

As a dermatologist, I recommend daily use of a broad-spectrum (UVA/UVB) SPF 15 or higher sunscreen for optimal sun protection. There is often confusion around SPF ratings. For example, SPF 20 means that you can stay in the sun 20 times longer than without sunscreen before starting to burn. However, consumers shouldn't become obsessed with overly high SPF values. A product with SPF 5 covers 80% of sun rays; SPF 10 covers 90%; SPF 20 covers 95%; and SPF 40 covers 97.5%. So, many believe the high protection of SPF 15 is good enough for everyday usage. Whatever the SPF value, wearing sunscreen should not give you a false sense of security.

For example, SPF measurements don't strongly factor in all the damaging UVA rays. So it's important to use a broad spectrum product formulated to also help block most UVA rays as well. Plus, the cumulative effect over a lifetime of the UVB & UVA rays that still get through when wearing sunscreen is not negligible. Application as frequently as needed is important (e.g., at least every two hours when sweating or swimming). Also, protective clothing and shelter during mid-day, at high altitudes, and from reflective surfaces can protect your skin from skin cancer and premature aging.