UV Radiation: What Is It?

What do suntans, sunburns, freckling, wrinkles, and Vitamin D have in common?  They are all created by ultraviolet (UV) radiation impacting our skin.  In last month’s article, we discussed the different types of skin cancer that can be caused by UV rays.  But what other effects does the sun and UV rays have on our skin?

Ultraviolet (UV) radiation from the sun comes in two primary forms:  UVA and UVB.  Each of these UV types can have different effects on our skin and health.

UVA is the most abundant form of ultraviolet radiation and accounts for 95% of the UV radiation hitting the earth’s surface.  It has the longest wavelength, allowing it to pass through clouds and windows, so it continues to impact our skin when we are driving in our cars and on cloudy days.  It also can penetrate into the deeper layers of our skin where it leads to collagen breakdown in the dermis.  Collagen loss over time causes skin to lose its fullness and produces wrinkling.  UVA is the dominant “tanning” ray and is the predominant form of UV found in indoor tanning booths.  Thus, UVA plays a predominant role in the development of sun freckling called “lentigines” and coarse, wrinkled, prematurely aged skin.  

UVB plays a primary role in skin cancer formation and skin reddening.  So, when you have that sunburned skin after a long day of yard work, it is the UVB to blame.   In contrast to UVA, UVB does not penetrate glass.  Interestingly, UVB also interacts with our skin as one source of Vitamin D.  We will discuss the relationship of Vitamin D and the sun in a future article, but it’s important to know that we can produce only a limited amount of Vitamin D from UVB and that can be obtained in only a few minutes of sun.  Moreover, Vitamin D is a fat-soluble vitamin that is readily available through our diet.  

Why is it important to know about the different UV rays types?  Beyond the skin cancer risk, there are so many undesirable skin changes that can develop over time from UV exposure:   sun spots; thin or crepey skin; wrinkles; and skin discoloration.  So, to keep our skin looking bright, vibrant, smooth, even-toned, and wrinkle-free, careful sun protection using broad-spectrum sunscreen that blocks both primary types of UV is important.  While we successfully perform laser treatments and offer medical products to remove these unwanted skin changes after they are there, as with most things prevention is always best!