How much daily sun exposure causes visible signs of aging?

Aging skin is visible due to a break down of its structure and elasticity over time. These changes are due to a combination of two types of aging, intrinsic and extrinsic. Intrinsic aging refers to the part of the aging process that is due to the actual passing of the years, wearing out of the body, and hereditary factors. Expression lines are a symptom of intrinsic aging.

You can develop lines from consistent and repetitive facial movements. Any repetitive movement of a facial expression such as raising the eyebrows, frowning, smiling, scowling, or any other facial movement will eventually cause a fold to occur. Intrinsic factors are also responsible for the natural slowing of collagen and elastin, and thinning of the dermis and epidermis. The cell renewal process is reduced and the shedding of skin cells slows, leading to a build-up of dead surface cells and therefore a dull appearance. Extrinsic aging factors are the effect of outside influences on the skin’s health. Extrinsic aging factors are considered the preventable causes, generally responsible for up to 85% of the visible signs of skin aging. Sun exposure, unhealthy lifestyles, environmental pollutants and chronic inflammation contribute to a breakdown of the skin’s structure.