Everyone knows that SPF stands for Sun Protection Factor. But what does that mean, and why should we care? Ultraviolet (UV) rays have a huge impact on how our skin ages, with approximately 80 to 85 percent of skin aging caused by UV rays!
Sunscreens are designed to reduce our exposure to UV radiation, which is an electromagnetic energy that is emitted from the sun and other sources such as tanning beds and some forms of lighting. There are three types of UV rays: UVA, UVB and UVC. Fortunately for us, UVC rays are almost completely absorbed by the Earth’s atmosphere, so protection from them is not believed to be necessary.
UVB rays, known as the “burning” rays, are the shorter, stronger rays that penetrate the outer layer (or epidermis) of the skin. But although redness and inflammation are the most obvious effects of a sunburn, what is happening within the skin is even more problematic. A cascade of damaging chemical reactions occurs, making the skin vulnerable to DNA damage and mutation – the number one cause of skin cancers. UVB rays can be blocked by a number of effective chemical sunscreens, and an SPF rating indicates the amount of protection for UVB rays: SPF 15 provides protection from 93% of UVB rays, SPF 30 from 97%, and SPF 60 from 98% of UVB rays.
UVA rays, known as the “aging” rays, are longer and able to penetrate down into the deeper dermal layer of the skin. They are the primary cause of premature visible aging, weakening and damaging the elastin and collagen that give skin its elasticity and firmness. UVA rays can also cause DNA damage and lead to skin cancer. It is important to note that an SPF rating applies to UVB rays ONLY. The U.S. has not yet implemented a rating system for UVA protection. And the skin can only be protected from UVA rays with a PHYSICAL sunscreen, one that sits on the surface and reflects UVA rays before they can cause cellular damage.
You can see why it is imperative to use a “broad-spectrum” sunscreen, one that provides protection against both UVA and UVB rays. For a sunscreen to be “broad-spectrum” it needs to contain either zinc oxide or titanium dioxide to provide the physical protection needed for UVA rays. The only way you can know this is to read the ingredient label.
As we get ready to head out on the trails and down the rivers, here are some tips to remember:
- Wear a “broad-spectrum” sunscreen on all areas of potential exposure.
- Apply 20 minutes before exposure, and reapply around every two hours of continued exposure.
- As much as possible, avoid exposure between 10:00 AM and 3:00 PM when UV exposure is highest.
- Reapply sunscreen after swimming, or any activities that result in heavy perspiration.
- If you are prone to burning, always wear a hat and protective clothing (redheads are particularly susceptible to sun damage).
- Wear sunglasses to protect the eyes and eye area.
- And please avoid tanning beds – they are particularly damaging.
Happy safe sunning!