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Risks of UV overexposure -

Overexposure to UV radiation is linked to a number of health issues, notably skin cancer. But what is UV radiation, and why can it be so hazardous? 

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What is UV radiation? -

Ultraviolet radiation (UV) is emitted by the sun in the form of rays. There are three types of UV radiation: UV-A, UV-B, and UV-C. So what's the difference? 

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UV-C -

UV-C is the shortest wavelength of the three forms of UV. This is the highest-energy, most dangerous type of UV radiation. Fortunately, UV-C is unable to penetrate Earth's atmosphere—it's absorbed by the ozone layer—so poses little or no risk. 

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UV-B -

The second-shortest wavelength, UV-B is the main culprit of sunburn. While it's mostly absorbed by the ozone layer, about 5% of UV-B nonetheless penetrates this stratospheric shield. There is a strong link between UV-B rays and skin cancer.

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UV-A -

UV-A is the longest wavelength and the deepest penetrating. It accounts for upwards of 95% of UV radiation getting through the Earth's atmosphere. UV-A causes skin aging, like spots and wrinkles, and is also associated with skin cancer. 

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Dangers of UV-C -

While naturally occurring UV-C is absorbed by the ozone layer, inorganic sources of UV-C radiation exist and are dangerous. Man-made sources of UV-C radiation include that emitted by welding torches and mercury lamps. 

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Germicidal UV-C lamp -

Another man-made source of UV-C radiation is a germicidal UV-C lamp. These devices are used to deactivate the DNA of bacteria, viruses, and other pathogens thus destroying their ability to multiply and cause disease. They were used widely throughout the COVID-19 pandemic. 

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Older UV-C tanning beds -

While most modern tanning beds emit UV-A radiation (which is still dangerous), older models may still use artificial UV-C radiation. It makes sense not to purposely expose yourself to harmful radiation. 

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Dangers of UV-B -

UV-B radiation penetrates and damages the outermost layers of your skin, the epidermis, in as little as 15 minutes of sun exposure. 

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UV-B exposure -

UV-B radiation is stronger or weaker depending on the time of day and season. Generally, the sun's UV rays are strongest between the hours of 10 am and 4 pm. 

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Skin cancer risk from UV-B -

UV-B radiation can cause basal and squamous cell skin cancer and melanoma. It can also promote cancer of the lip and eye. UV-B has also been linked to Merkel cell carcinoma, a rare and aggressive type of skin cancer. Furthermore, UV-B rays do age skin over time. 

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Dangers of UV-A -

Prolonged exposure to UV-A radiation allows the rays to penetrate deeply into the dermis layer, which can damage the DNA in skin cells. 

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Damage to skin caused by UV-A -

UV-A rays can tan your skin in minutes. But damaged DNA can produce genetic defects, or mutations—disorders that can lead to premature aging of the skin and skin cancer. 

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Hidden danger of UV-A -

And UV-A poses an additional hazard to health. Unlike UV-B and UV-C, UV-A rays can penetrate clouds and glass, causing potential harm on overcast days or even through your windshield. 

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Global Solar UV Index -

The Global Solar UV Index (UVI) is a simple measure of the UV radiation level at the Earth's surface. The higher the index value, the greater the potential for damage to the skin and eyes.

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Damage to eyes -

Damage to the eyes caused by excessive exposure to sunlight extends to the development of cataracts. Cornea damage and vision loss can also occur as a result of prolonged exposure to UV radiation. 

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Risk to immune system -

According to the United States Environmental Protection Agency (EPA), overexposure to UV radiation may suppress proper functioning of the body's immune system and the skin's natural defenses. This reduces the skin's ability to fight off foreign invaders such as cancers and infections. 

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The most hazardous UV radiation based on exposure -

While UV-C is the most dangerous type of UV radiation, it's only a risk to those exposed to artificial sources of UV-C. As previously explained, naturally occurring UV-C is blocked by the ozone layer. So what is the most hazardous form of UV radiation based on exposure? 

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Exposure to UV-A -

UV-A is potentially the most dangerous form of radiation because it accounts for nearly all UV exposure, barely unfiltered as it is by the Earth's atmosphere. 

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Exposure to UV-B -

Although only a small amount of UV-B escapes the ozone layer, this type of UV radiation is blamed for much of the long-term damage from the sun. This is because it comes with the highest skin cancer risk. 

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Who's especially at risk? -

Anyone can have harmful health effects from UV radiation, even those with dark skin. But the risks increase in people who spend a lot of time in the sun or have been sunburned frequently. 

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Light-skinned people -

People with light-color skin, hair, and blue or green eyes are at greater risk of UV radiation. 

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Children -

Infants and toddlers are particularly vulnerable to skin changes caused by UV radiation. This is because they have lower levels of melanin and a thinner outermost layer of skin. 

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How much sun? -

Interestingly, around 25% of lifetime sun exposure occurs during a person's first two decades of life, according to Better Health.

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Critical exposure period -

In fact, notes Better Health, UV exposure during a person's first 18 years of life is the most critical for cancer-causing skin damage and skin aging. 

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Sun protection tips -

Depending on your location and time of year, the sun is usually at its peak between 10 am and 4 pm. Head indoors or under shade during these hours. 

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Apply sun screen -

If you stay out during this period, either for work or play, be sure to apply sunscreen with a high S.P.F. (at least 30) and wear sunglasses.  

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Use lip sunscreen -

Your lips are just as susceptible to the sun's radiation as the rest of your body, which means they're vulnerable to skin cancer. Using lip sunscreen of S.P.F 50 that filters out harmful UV-B rays gives you protection from this often overlooked cancer. 

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Wear a hat -

And remember to crown yourself with a broad-rimmed hat and wear light breathable cotton fabrics. 

Sources (National Cancer Institute) (World Health Organization) (EPA) (Better Health)

See also: How to survive heat waves this summer.

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