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In our May newsletter, we covered Skin Cancer Awareness month. In that article, we talked about sun safety and the importance of using a broad spectrum (UVA/UVB) sunscreen to prevent sun damage to your skin. But what exactly are UVA and UVB, and how does it damage my skin? Because July is UV safety month, we’ll cover ultraviolet (UV) basics and give you the information you need to make good UV safety decisions. You may also want to reference our article last month—May is Skin Cancer Awareness Month—for additional skin cancer safety information.

What is ultraviolet radiation?

Skincancer.org provides a great definition of UV radiation: “UV radiation is part of the electromagnetic (light) spectrum that reaches the earth from the sun.” [1] This light is made up of wavelengths. Some you can see and some you can’t. The light you can’t see is called the ultraviolet light, and it’s divided into two different categories based on nanometers. For example, you can see light between 700 and 400 nanometers. The light between 400 and 320 nanometers is called UVA, and the light between 320-290 nanometers is called UVB. (A UVC category also exists, but those rays are usually absorbed by the Earth’s atmosphere. [2])

Here’s a picture from skincancer.org that illustrates the light (and UV) spectrum:

UV light spectrum

How does ultraviolet radiation affect my health?

We all know that UV exposure increases your chances for developing skin cancer, including melanoma, the deadliest form or skin cancer. But UV exposure can also adversely affect your eyes, weaken your immune system, and age your skin. [3]

In May, we covered many of the ways to protect your skin, especially during these sunny summer months. Revisit that article for additional details on sunscreen and avoiding sunburns.

Make an appointment today

As always, let us know if you have questions or need to schedule an exam. We look forward to seeing you here at Horizon Family Medical Group.


  1. http://www.skincancer.org/prevention/uva-and-uvb
  2. https://www.cdc.gov/niosh/topics/sunexposure/default.html
  3. https://foh.psc.gov/calendar/july.html