Many people understand that the sun is one of the main culprits in aging the skin and doctors are constantly reminding us to “Wear sunscreen!”. When the warm weather arrives, it can be easy to let this advice slip through one ear and out the other. What people may not understand is just how the sun’s rays affect the skin in the long term. It is deeper than you think.
Many older sunscreens on the market were “SPF” sunscreens. This means that they blocked UVB rays, responsible for sun burns that we experience in the outer layer of our skin, the epidermis. When sun protection factor is clinically determined, it is accomplished by testing how long the sunscreen can protect until a burn is incurred. So SPF = UVB. But what about UVA rays? UVA rays are longer wavelength rays that can penetrate more deeply into the skin. They can reach the dermal layer, which houses our fibrous proteins: collagen and elastin. UVA radiation damages these proteins which provide youthful volume and resilience to skin that we all cherish so dearly. When collagen and elastin become broken, they no longer keep their structure forming and elastic properties and skin becomes less voluminous and less able to bounce back. Over time, this damage becomes visible as sagging and wrinkling.
So while you may be diligent in applying SPF 50+ sunscreen, you may not be shielded from UVA and its effects. Even though burning or tanning is not evident, UVA acts on cells that produce collagen and elastin (fibroblasts) and on the structural matrix found below the epidermis (consisting of collagen and elastin). This is where Broad Spectrum SPF comes in. Canada and the U.S. allow for “Broad Spectrum” claims for sunscreens that provide UVA protection. It provides a measurable amount of UVB protection (SPF) and some UVA protection (although it is not clearly indicated how much). In Japan, they have a PA system which indicates the level of UVA protection of their products with the use of + symbols (+, ++, +++, and ++++) based on in vivo assessment following ISO 24442:2011 standards. Four ++++ indicates the highest level of UVA protection in Japan. Korea also uses the PA system, however the highest protection is indicated by 3 +++ symbols. It is important to note that the PA system is not internationally recognized at the moment and is not Health Canada or FDA approved. Therefore, it is important to opt for Broad Spectrum SPF sunscreens to mitigate the sun’s effects on your skin, not only for cosmetic purposes but for health reasons as well. While the amount of UVA protection is not clearly represented in Broad Spectrum claims, it is better than an SPF only sunscreen at the moment.
While sunshine is important for our bodies to naturally synthesize vitamin D, too much sun exposure ages your skin prematurely. The most superficial fibroblasts of the dermis undergo cell death from deep penetrating UVA rays, leaving behind empty space. There is also an increase in collagenase activity in response to UVA radiation (collagenase is an enzyme responsible for destroying collagen). However, it is not all so grim. The dermis does have the capability to repair itself to a degree. UVA reaches mostly into the upper layer of the dermis, leaving the less superficial fibroblasts unaffected and intact. These fibroblasts are capable of proliferating and recolonizing the space left behind from the cells that underwent apoptosis (cell death). This is also where the collagenase is thought to have a role in helping to carve a path through the dermal matrix in order to make way for fibroblasts to migrate and fill in the empty space left behind from the cells that died off.
Contrary to the constantly renewing nature of the epidermis, this dermal response is more of a reaction to injury. Repeated, unprotected exposure to UVA rays causes an accumulation of aging effects and can alter the dermal matrix, actually hindering future collagen production. As collagen production decreases naturally after reaching maturity, the effects of sun exposure become more marked and less reversible. While the dermis shows some ability to repair in response to sun damage, with age, fibroblasts become fewer and their ability to make collagen and elastin is reduced. Therefore, it is in your best interest to keep sun impact on your skin minimal to preserve its natural youthfulness and to avoid pre-mature aging. One way to do that is to ensure that you use Broad Spectrum SPF products for your face and body on those hot, sunny days!