Skip to main content

What’s the Difference Between UV-A, UV-B, and UV-C Light?

Most of us think of two things when we hear the word ultraviolet: sunburns and the band U2. But there’s a lot more to UV light than that. Yes, UV rays can give you a painful, lobster-like appearance. And yes, Achtung Baby did win a Grammy. But there are details about UV light that affect your everyday life even more than those things.

In this post, we’ll address questions like the following:

  • Does UV light kill mold?
  • Does UV light kill fungus?
  • What type of UV light is used to kill bacteria?

But let’s start with the basics.


What is UV Light?

You may wonder whether UV light is the same light coming from your blue-light-emitting devices like smartphones, tablets, and televisions. These are not the same. Blue light is on the visible light portion of the light spectrum. These visible light waves can range from violet light at 380 nanometers in length to red light at 700 nanometers.

On the other hand, UV light is just outside of visible light on the light spectrum. That means it’s not the type of light that we can see with our eyes.

What are the three types of ultraviolet light?

In terms of wavelength, the three types of UV light go in this order:

  • UVC is the shortest wavelength and the farthest from visible light.
  • UVA is the longest wavelength and the closest to visible light.
  • UVB is in the middle of UVC and UVA.

Each type of UV light comes naturally from the sun. Thankfully, our corneas and lenses protect our retinas from potentially damaging UV rays. You may also be familiar with artificial sources of UV radiation, like lasers, tanning beds, mercury vapor lighting, and some halogen, fluorescent, and incandescent lights.


What’s the Difference Between UVA, UVB, and UVC?

Now that we’ve introduced you to these three types of UV light, let’s dive deeper into their differences. We’ll help you understand the risks and potential benefits of each.


We’ll start with UVC, the type of UV light we use for sterilization. UVC rays are the only type out of these three to be completely obstructed by the Earth’s ozone layer. That’s right. The ozone layer blocks 100% of these rays from getting through. Otherwise, we’d be in trouble, because they can do serious damage.


Like UVC rays, the Earth’s ozone layer impedes UVB rays – just not entirely. About 10% of UVB rays pass through the ozone layer and reach us. These have a wavelength that can affect as far as the epidermis, or outer layer of our skin. You can attribute that sunburn you got on your last vacation to UVB rays.


UVA rays make up the majority of UV rays we come into contact with because they can pass through the Earth’s ozone layer. These have a wavelength that can reach further than UVB, to the dermis, or middle layer of our skin. These are the primary culprits when it comes to wrinkling and aging of the skin.


Effects of UV Rays

There are some reasons to take precautions when it comes to UV exposure. For example, we’ve known about the potential dangers of tanning beds for years. Like UVB, UVA rays can damage your skin, either in the short term as a sunburn or in the long term as aging and skin cancer. But are there any health benefits to the use of UV light? Let’s take a look.


Health Benefits of UV Light

Here are some of the potential health benefits of UV exposure:

  • Depending on various factors, like your diet and geographical location, some UVB exposure may help your skin produce vitamin D3.
  • UV radiation can be used to treat people with conditions like Rickets, Psoriasis, and Eczema.
  • UV lamps have been used effectively to kill mold.
  • UVA and UVB radiation can kill fungal spores.
  • People have effectively used UVC radiation for many years to reduce the spread of bacteria.

The kind of UVC light used in toothbrush sanitizers and other germicidal gadgets is artificial and safely contained. When you consider that your toothbrush can harbor millions of germs between brushings, a germicidal light is a major advantage in the battle for your health. A UV-C light can disinfect and destroy up to 99.9% of germs on your toothbrush in just three minutes.



We hope you now have a better understanding of what UV light is, as well as its dangers and benefits. Health concerns are present even in its naturally occurring form. Fortunately, our ozone layer protects us from much of the danger.

We know there are health benefits to certain UV exposure and try to harness those benefits safely, like being out in the sunlight while also applying SPF sunscreen. Scientific advances allow the use of UV light in a controlled manner for all sorts of health treatments. There are now easy and affordable ways to use UV light to improve your health daily.




  1. Braga GU, Rangel DE, Fernandes ÉK, Flint SD, Roberts DW. Molecular and physiological effects of environmental UV radiation on fungal conidia. Curr Genet. 2015 Aug;61(3):405-25. doi: 10.1007/s00294-015-0483-0. Epub 2015 Apr 1. PMID: 25824285.
  2. Centers for Disease Control and Prevention: UV Radiation.
  3. DestructiveCreativity: Science behind UV light! – Ultraviolet radiation UVA UVB and UVC light.
  4. Healthline: What’s Blue Light and How Does It Affect Our Eyes?
  5. Johns Hopkins Medicine: Ultraviolet Radiation.
  6. S. Environmental Protection Agency: Does Ultraviolet (UV) Radiation from UV Lamps Kill Mold?
  7. S. Food and Drug Administration: Ultraviolet (UV) Radiation