What adverse effect does UV radiation have on hair?

UV radiation can have a significant adverse effect on hair by causing color fading. This occurs because UV rays penetrate the hair shaft and degrade the pigments responsible for its hue. Over time, exposure to sunlight can lead to the oxidation of hair color, whether natural or chemically treated, resulting in a noticeable loss of vibrancy and depth. This effect is particularly pronounced in color-treated hair, where the artificial dyes are often more susceptible to fading in the presence of UV rays.

In contrast, options suggesting that UV radiation strengthens the hair, enhances shine, or promotes growth do not accurately reflect the impact of UV exposure. Strengthening hair typically involves the use of conditioning treatments and proper care, rather than UV exposure. While some elements of light reflectivity (shine) can be influenced by healthy cuticles or products, UV radiation does not enhance these properties and can actually damage the outer layer of the hair, leading to dullness. Additionally, there is no credible evidence indicating that UV radiation promotes hair growth; instead, excessive exposure can lead to more problems like dryness and brittleness, impeding healthy hair growth.