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UVA, UVB and even UVC rays, oh my! What do they all mean? And, should you be concerned about one more than the others when you’re enjoying time outside at the family barbecue? The short answer about one being worse than the other is yes, and we’ll answer any “sunburning” questions you may have as we go. Before you get too worried, though, just make sure not to overdo it when you're outdoors – and follow our helpful tips for protecting your skin with sunscreen!

What is UV Radiation?

If you remember from your science class, the abbreviation in UV Radiation stands for ultraviolet radiation. Ultraviolet radiation is a non-ionizing kind of radiation, and there are many different types of ultraviolet (UV) rays that exist in our world.

Meanwhile, there are just three main types of UV rays that are relevant when it comes to sun exposure: UVA, UVB, and UVC. These UV rays are emitted from natural sources like the sun or from man-made sources like the fluorescent bulbs in tanning beds.

Three Main Types of UV Rays

UVA, UVB and UVC radiation have several differences. For one, they are classified by their wavelength, with UVA having the longest wavelength (315-399 nm), UVB having a medium wavelength (280-314 nm) and UVC having the shortest (100-279 nm). Other main differences between them include their energy levels and their effects on the skin, which we discuss in detail below:

  • UVB Rays: Having medium energy levels and affecting the top layer of the skin, UVB rays are the most effective at giving you a tan. Short-term effects due to UVB exposure are a delayed tan, sunburn and blisters, while the long-term effects include skin cancer and premature aging. The primary sources of UVB radiation include the sun and tanning booths.
  • UVC Rays: These rays have the shortest wavelengths and highest energy levels of the three. As a result, they could cause serious damage to the skin if they weren't completely filtered out by the earth's ozone layer. The primary sources of UVC radiation you can encounter are artificial and include UVC lights, mercury lamps and welding torches.
  • UVA Rays: UVA rays have the lowest energy levels. Skin cells affected are the inner cells in the uppermost layer of the skin, to include the dermis. Short-term effects of UVA radiation are nearly immediate tanning, sunburn and blistering, while long-term effects are premature aging, wrinkles and some skin cancers. Like UVB rays, the primary sources of UVA radiation are the sun and tanning booths.

What to Know about UVA Rays

Most UVB radiation and all of the UVC radiation doesn’t reach the earth, thanks to the earth’s ozone layer. That means that nearly all of the UV radiation that makes it through to earth (approximately 95%) is UVA. There are certain risks associated with exposure to it, such as age-related spots and wrinkles since it does reach so deeply into skin layers.

Moreover, UVA rays quickly tan and burn your skin, and they are linked to skin cancer. UVA rays, unlike the others, can penetrate clouds and glass and clouds, causing risk to your skin on overcast days or through your vehicle's windshield. 

So, there’s the answer to the question in the intro: Which of the UV rays are the worst? It’s UVA rays, and they get their bad rap since they are prevalent, pose the most risk and come at you from all directions. However, we’re not letting the other two off the hook, so read on to find out what you need to know about them too.

What to Know about UVB Rays

UVB has the second shortest wavelength, and although only 5% of UVB rays make it through to the earth, it harms the skin's epidermis (top layer of skin) in as little as 15 minutes of sun exposure. Because of this, it is the main source of sunburn, a major source of skin cancer. 

What to Know about UVC Rays

While UVC rays are absorbed by the earth's atmosphere, UVA and UVB rays can reach people on land and under the water. Although UVC radiation doesn't penetrate the earth's atmosphere, inorganic examples of it exist and are hazardous if you don’t use the tools properly. Below is a list of commonly used artificial UV lights that can present a significant health risk in some circumstances:

  • Man-made sources of UVC, like germicidal UVC lighting, welding torches and mercury lamps can adversely affect your health if you are careless with them.
  • Tanning beds and sun lamps are known carcinogens (cancer-causing substances).
  • UVB light therapy, which uses special UVB radiation to treat psoriasis, is not for everybody. Candidates who have had skin cancer or use certain topical medicines should not use UVB light therapy.

Try Out Our UV Ray Index Chart

The UV Ray Index provides a forecast of the expected risk of overexposure to UV radiation from the sun, provided by the National Weather Service and the EPA. If you would like to know the risk for your area before heading out to the beach with friends, simply enter your location in the search field on our website to find out your local UV index for that day.

When are UV Rays Strongest?

There are environmental factors that can affect when UV rays are strongest, including:

  • The seasons: UV exposure is highest during the spring and summer, but the sun can still affect you in the colder seasons.
  • Time of day: The worst time for UV exposure is between 10 am and 4 pm. During this period, the sun’s rays don’t have as much distance to cover, making them much more powerful.
  • Ozone: The ozone layer protects us from UV rays. Unfortunately, aerosolized pollutants have caused the ozone layer to thin and amp up the UV intensity.
  • Latitude: You can get a very bad sunburn in areas on or near the equator. The reason? UV rays have less distance to travel before they reach the ground in these areas. The same effect happens with high altitudes.
  • Clouds: Clouds filter out a good bit of the UVA and UVB rays before they reach the ground. However, all clouds are not created equal. Those that are dark and water-filled may block out more UV rays than those that are high and wispy.
  • Reflection: Remember those ladies in the classic movies that used to sunbathe with foil reflectors under their chins? They don’t do that anymore, but UV rays reflect off surfaces such as water, snow, sand, and pavement to hit you all over like the sun’s ray did when they bounced off those reflectors and hit those ladies’ faces. The bottom line: You are subjected to more UV exposure.

The Sun is Healthy – Here’s How to Protect Yourself

Now that all the deep stuff’s out of the way, it’s time to have fun! Let’s start by pointing out that it’s healthy for you to get out in the sun, and WHO recommends that you spend 5 -15 minutes out in it’s rays 2 - 3 times a week. When you do, UV radiation benefits your body by helping it to make vitamin D, which, in turn, builds strong bones and helps you absorb calcium and phosphorus from what you eat.

You can have your fun outside without worries if you take the following precautions:

  • Stick to shady areas, especially when it’s around midday.
  • Wear apparel that covers up your arms and legs.
  • Wear a hat with an extra wide brim to protect your head, ears, face and neck.
  • Wear sunglasses that state they have UV protection lenses. They should be of a wraparound style, too.
  • Use a broad-spectrum sunscreen with SPF of 50 for both UVA and UVB protection.
  • Be especially vigilant about children. They need everything on the list above and for their medicines to be checked too.


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