Is UV light harmful to eyes? Learn about the three different UV radiation levels of light and what you need to do to protect your eyes and skin.
As spring and summer return, we enjoy getting outside again, especially on those warm, sunny days. Many people like to go lie on the beach and work on that summer tan. As the bearer of weather warnings, I’d say, “Not so fast!”
Part of that sunlight (the solar spectrum) comprises ultraviolet (UV) radiation. Radiation refers to energy in the form of waves; in this case, those emitted by the sun. UV radiation can be divided into three categories: A, B, and C. UV-C is harmful to plants and animals, but, fortunately, it’s absorbed by the ozone layer in the stratosphere. This is why the “hole in the ozone layer” caused by human-produced chemicals is so concerning (amazingly, the world’s countries came together to work on this crisis). UV-A and UV-B, however, mostly make it down to the Earth’s surface. UV-B is harmful, and although humans need UV-A to synthesize vitamin D, too much can also hurt you.
Is UV Light Harmful?
What are the risks inherent with UV exposure? A sunburn is due to UV rays. Burns can range from mild pain to blistering of the skin. The most serious cases lead to hospitalization. Over time, prolonged exposure to UV rays will cause the skin to dry out, wrinkle, and age prematurely, which is probably not the look you were going for. Even worse, skin cancer, including deadly melanoma, has been linked to intense UV ray exposure. Skin cancer can be treated; make sure you see a dermatologist regularly. Also, eyes are extremely sensitive to UV rays, and exposure can lead to cataract development.
Skin type is a major determinant of UV-induced damage risk. The most susceptible individuals are those with fair to pale skin that never tans, red hair, freckles, and blue eyes. The least susceptible are people with dark skin, dark eyes, and dark hair, although people of all skin types should still take measures to protect their skin and get regular checkups.
When Are You at Greatest Risk?
UV radiation and general sunlight are strongest around solar noon, when the sun is directly overhead and its rays pass through less of the atmosphere, whereas other times pose much lower risk. Solar noon is the time of day when the sun is at its highest point in the sky, halfway between sunrise and sunset. Local noon time typically varies from this. This doesn’t coincide with the highest temperature, which usually occurs a few hours later, because it takes time for the environment to warm up during the day.
How Else Can You Be Exposed?
There are several factors to consider for UV exposure. Elevation is one. The higher you are, the less atmosphere sunlight passes through, thus the greater UV intensity is. Thicker clouds can significantly reduce UV rays, but thinner cloud cover doesn’t offer much protection. UV rays can also reflect off water and light-colored sand, even if you’re not in direct sunlight.
Over the course of a year, the UV threat is greatest in late spring, near the summer solstice, and into the summer months. For many, this is the peak time for outdoor activities. As for location, the farther south you are, the stronger the sun’s rays and UV rays are. In the U.S., Hawai’i has the strongest, with South Florida a close second.
The UV Index
To alert the public about the risk of UV danger, the UV Index was developed in Canada in 1992 and adopted by the National Weather Service (NWS) in the U.S. as well by the World Health Organization in 1994. This gives a numerical value to the expected daily peak risk. It ranges from 0 at night to 16 during the day in the tropics. Some skin or eye damage can occur with readings of 6, and values this high and higher are common throughout the lower 48 states and southern Canada in summer. Readings of 11 or more indicate extreme risk and occur regularly in South Florida, Hawai’i, and Puerto Rico during summer, but they can also occur farther north. In the U.S., the NWS issues daily UV forecasts for the following day, which are distributed by the Environmental Protection Agency (EPA). They’re typically included in standard media forecasts and are available on www.EPA.gov/sunsafety. In Canada, Environment Canada provides UV forecasts through Canadian Weather.
How to Protect Yourself
First, don’t try to ensure you’re getting a tan. If possible, avoid being outside, or at least stay in the shade during midday (10 a.m. to 4 p.m.). Sunscreen has been the standard for UV protection for many years. Make sure it’s SPF 30 or higher. Reapply every two hours of sun exposure, or more often if swimming or sweating heavily. Additionally, choose a sunscreen that’s environmentally friendly and nontoxic to marine life. If you prefer not to apply sunscreen, consider UV-protective clothing. Maximum protection would include long-sleeved shirts and long pants. Wide-brimmed hats will protect your face, head, and neck. UV-blocking sunglasses will protect your eyes. Make sure you also protect your feet, which can easily burn. Be especially proactive with children, and don’t expose babies under 6 months to direct sunlight.
Sources
National Weather Services: www.Weather.gov/safety/heat-uv
Government of Canada Weather: www.Canada.ca/en/environment-climate-change/services/
Environmental Protection Agency UV Index Application: www.EPA.gov/sunsafety/uv-index-1
Ed Brotak taught college students about weather for more than 30 years and led many of them to pursue careers in meteorology. He lives in Asheville, North Carolina, with his wife (who’s also a meteorologist).
Originally published in the May/June 2026 issue of Grit magazine and regularly vetted for accuracy.
