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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?
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.
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?
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.
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.
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.
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.
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.
UV-B radiation penetrates and damages the outermost layers of your skin, the epidermis, in as little as 15 minutes of sun exposure.
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.
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.
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.
Prolonged exposure to UV-A radiation allows the rays to penetrate deeply into the dermis layer, which can damage the DNA in skin cells.
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.
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.
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.
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?
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.
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.
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.
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.
People with light-color skin, hair, and blue or green eyes are at greater risk of UV radiation.
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.
Interestingly, around 25% of lifetime sun exposure occurs during a person's first two decades of life, according to Better Health.
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.
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.
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.
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.
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.
For many of us, the summer season is an excuse to dress down and enjoy the sun. But hot, dry weather brings with it hazards that some choose to ignore. And the greatest risk is an invisible one—harmful UV radiation. UV-A, UV-B, and UV-C are forms of ultraviolet light rays emitted from the only star in our solar system. These three types of radiation are damaging to humans though fortunately the most dangerous one is absorbed by the ozone layer. But what of the other two? How great is the peril of prolonged exposure to the sun's rays, and what are the potential consequences?
Click through and become more aware of the dangers of UV radiation.
What are the dangers of UV radiation?
Are you aware of the severe consequences of sun exposure?
HEALTH Lifestyle
For many of us, the summer season is an excuse to dress down and enjoy the sun. But hot, dry weather brings with it hazards that some choose to ignore. And the greatest risk is an invisible one—harmful UV radiation. UV-A, UV-B, and UV-C are forms of ultraviolet light rays emitted from the only star in our solar system. These three types of radiation are damaging to humans though fortunately the most dangerous one is absorbed by the ozone layer. But what of the other two? How great is the peril of prolonged exposure to the sun's rays, and what are the potential consequences?
Click through and become more aware of the dangers of UV radiation.