MDSolarSciences Explains UVA and UVB

By on June 17, 2015, in Beauty Knowledge Center, Soft Surroundings

Dr. Freidman

“If it doesn’t say broad spectrum on the label, you’re basically wasting your time,” says founder and CEO of MDSolarSciences, Dr. Robert Friedman. Strong words, but what do they really mean? Almost all of us are used to thinking about sun protection by the numbers. SPF, or sun protection factor, has long been considered the only thing that matters. The common perception is that a higher number equals more protection. While this is not necessarily a misconception, it really only tells half the story. In order to understand the true nature of sun protection, we have to ask a very important question:


The Spectrum

The light from the sun travels in waves that can easily be split into two groups: visible (or infrared) and ultraviolet (UV). Visible light, as the name suggests, can be seen by the human eye. It gives us the brilliant colors of the rainbow, and provided us with the most iconic album cover of all time. When dealing with sun protection, however, we only need to worry about UV light. UV radiation is a proven human carcinogen and can be broken down into two types based on the length of the waves. The long-wave rays are known as UVA, and the shortwave rays are known as UVB. Together they make up the “spectrum” in broad spectrum. What does this mean for your skin? As it turns out, the differing wavelengths allow these two forms of radiation to damage your skin in different ways. There is a simple way to understand the effects of UVA and UVB rays. UVA= aging, and UVB= burning.


Sunburn: the bane of beachgoers everywhere. We don’t have to remind anyone that red, burnt, stinging skin is never in style. The culprit here is UVB radiation, the main cause of sunburn. They do their damage right at the point of impact: the top layer of skin. This is why we can actually see the damage being done. UVB rays are much shorter and much more intense than UVA rays. The intensity varies throughout the year, ramping up in the summer months just as we feel the need to get outside and enjoy the warmth. Another thing that affects UVB intensity is altitude. Ever get a sunburn while skiing? It seems counterintuitive, but it actually makes perfect sense. Being closer to the sun makes quite a difference. Also, that beautiful powder bounces those rays back up at you, providing even more exposure. The short, concentrated UVB rays bounce off other things, as well. For example, your car or office window offers great protection from UVB radiation. Protecting yourself from sunburn is important, but it can also lead to a false sense of security. There is another threat to your skin that requires year-round protection.


No sunburn no problem, right? Not if UVA has anything to say about it! UVA make up 95% of the UV radiation that reaches Earth. The longer wavelengths make them less intense than those of UVB, but there are 30 to 50 times more UVA rays at any given time. UVA rays are longer than UVB, allowing for deeper skin penetration, which causes wrinkling, discoloration, and aging. Because there is no painful, immediate consequence of UVA exposure (like the sunburn caused by UVB), too many people take an “out of sight, out of mind” attitude to UVA protection. Just because you can’t see the damage being done, don’t think that you aren’t being exposed. Unlike UVB, UVA rays are consistent throughout the year. UVA rays can also pass through clouds and glass, meaning that we are always exposed to UV radiation. You may not burn while driving your car on that long summer road trip, but you can certainly open yourself up to another kind of danger. So now that you know what you’re up against, how do you make sure you’re fully covered?


Simply put, a broad spectrum sunscreen provides protection against both UVA and UVB rays. It covers the full spectrum of UV radiation, giving you complete coverage. So what about those SPF numbers that have long been the one and only thing that people care about? While important, SPF only deals with UVB rays. The SPF numbers tell you how long it will take for UVB rays to burn your skin with the product versus without the product. SPF has absolutely nothing to do with UVA rays. In order to be fully protected from the sun’s harmful rays, a product needs to cover the entire UV spectrum. It needs to have active ingredients working together to protect you from UVA and UVB radiation. In other words… if it doesn’t say broad spectrum on the label, you’re basically wasting your time.

This article was published by MD SolarScience on their blog, “S.H.E. Explains…” on August 13, 2014 at and has been used with permission. 

Shop the MD Solar Sciences Collection.