How does sunscreen work?
Sunscreen lotions work by absorbing, reflecting or scattering UV light. Sunscreen ingredients are either physical (reflecting) or chemical (absorbing, scattering) in nature. Many products contain a combination of ingredients. Regardless of the combination of ingredients, it is important to select a product that rates its level of UVA protection.
What does SPF mean?
SPF (Sun Protection Factor) measures how long it takes sunscreen protected skin to begin to sunburn (turn red) as compared to unprotected skin. For instance, if it takes unprotected skin takes 10 minutes to burn, then sunscreen protected skin with a SPF value of 15 will take 150 minutes to burn. SPF values only rates the level of UVB protection.
What are UVB rays?
UVB rays produce the familiar sunburn. They also cause skin cancer. SPF (Sun Protection Factor) ratings effectively rate the level of UVB protection provided by sun protection products. The UVB rays with short wavelength and high energy produce a burning effect (sunburn), confined predominately to the surface of the epidermis.
What Are UVA Rays?
UVA rays have a longer wavelength than UVB rays, penetrating deeper into the skin, and produce the aging associated with chronic sun exposure such as: skin sagging, loss of elasticity, pigment changes, deep wrinkles, and dry skin. Recent studies have shown a strong link between UVA rays and the development of melanoma. Critical Wavelength® (CW) is the international standard to rate the level of protection against UVA rays.