UAB Medicine News


UV Rays Explained: Staying Safe in the Sunshine

Spending time outdoors on warm, sunny days is one of the best parts about summer. Sunshine triggers the body’s natural production of vitamin D and works wonders for boosting moods. But too much time in the sun can lead to serious consequences if you don’t protect yourself properly.

Types of Ultraviolet Rays

Ultraviolet (UV) rays from the sun are a major risk factor for skin cancer, and there are three main types of UV rays: UVA, UVB, and UVC. UVA, or long-wave rays, make up about 95 percent of the radiation that we experience. These are much more prevalent than UVB rays, but they are also less intense. UVA rays are present in our atmosphere at all times of day, even when it’s cloudy outside.

UVB, or short-wave rays, are more intense and are a leading cause of skin damage, skin aging, skin cancer, and eye damage, including cataracts. UVB rays are the most common cause of sunburn and other substantial damage to the outer layers of skin. UVB rays peak in our region between April and October, between 10 am and 4 pm.

UVC rays have more energy than UVA and UVB rays. However, these are absorbed by the Earth’s ozone layer and do not reach us, so this article focuses on UVA and UVB rays.

Health Risks

Both UVA and UVB rays can lead to skin damage and skin cancer, but the health risks of the sun go beyond this. The most common type of skin cancer caused by UV rays is melanoma, which can affect people of any age. Other types include basal cell carcinoma and squamous cell carcinoma, which can cause serious tumors and spread to other parts of the body.

Even if your exposure to UV rays does not lead to cancer, it still can cause premature aging of the skin, including wrinkles, redness, and a leathery appearance. Parts of the body that receive the most sun exposure over time, such as the hands and neck, are particularly susceptible to UV ray damage. Your eyes also can suffer from prolonged sun exposure, leading to cataracts (a clouding of the eye’s lens) and even blindness. A reduction in eyesight and skin cancer around the eyes can result from not wearing proper eye protection while outdoors. Research also shows that exposure to UV rays can weaken the immune system, making your body less capable of fighting off sickness and disease.

How to Prevent UV Damage

Although certain types of skin cancer are hereditary and not necessarily caused by excess UV ray exposure, many types of skin and eye conditions can be prevented by taking precautions. Sunscreen is a great way to protect your skin, but seeking shade or staying indoors during peak UV ray hours is even better. Unlike UVB rays, UVA rays can penetrate glass, so keep this in mind when driving. It’s a good idea to watch or read the local news to learn what the UV index is and understand how strong the UV rays will be that day.

When you spend time in the sun, opt for clothing made of fabrics that are resistant to UV rays. Many types of athletic wear have UV protection, and there are even laundry additives you can put in the wash to increase the UV protection of your clothes. Choose tightly woven and loose-fitting clothing to provide the most protection, and don’t forget to protect your head and neck with a wide-brimmed hat.

With regard to sunscreen, choose one that protects against both UVA and UVB rays, since both are harmful to the skin. A sunscreen with a sun protection factor (SPF) of 30 means that it blocks about 97 percent of the sun’s UVB rays, while SPF 50 sunscreen will block about 98 percent. Keep in mind that SPF does not measure the product’s protection against UVA rays. Also, for any sunscreen to be effective, you need to reapply it at least every two hours or even more often if you’re swimming or sweating a great deal.

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