ULTRAVIOLET RADIATION
We are exposed to ultraviolet radiation through the sun, and some man-made resources like welding and tanning beds. UV rays are a moderate-frequency radiation which can damage the DNA, or genetic material, in cells which may lead to cancer or damage to the eyes.
THERE ARE 3 TYPES OF ULTRAVIOLET RADIATION:
UVA rays have the least energy and can cause skin cells to age, mainly exhibited by wrinkles, and can lower your body’s immune defenses. They are also suspected to play a role in some skin cancers. About 95% of the ultraviolet rays from sunlight are UVA rays.
UVB rays have a bit more energy than UVA rays and can directly damage the DNA of skin cells. These are the rays that cause sunburns and believed to be to source of most skin cancers. They too contribute to skin aging and decreasing your body’s immune defenses, and cause snow blindness (a sunburn to the cornea). About 5% of the ultraviolet rays from sunlight are UVB rays.
UVC rays have the most energy of the ultraviolet rays. They react with the ozone in our higher atmospheres and don’t typically reach the ground and are not normally associated with risk for skin cancer. These rays are the ones which come from man-made sources such as arc welding torches, UV sanitizing bulbs and mercury lamps.
DIFFERENT FACTORS AFFECT ONE’S EXPOSURE TO UV RADIATION:
Time - UV rays are strongest between 10 am and 4 pm.
Season - UV rays are stronger during the spring and summer months.
Latitude - UV exposure is less as you move farther from the equator.
Altitude - More UV rays reach the ground in higher elevations.
Clouds - Exposure may vary when the skies are cloudy, but it is important to know UV rays can get through to the ground despite the lack of visible sunshine.
Reflection - UV rays can bounce off of surfaces like water, sand, snow, pavement, and even grass. This can increase UV exposure.
Air - Ozone in the upper atmosphere filters some of the UV radiation.
UV RADIATION AND SKIN CANCER:
There is a direct link between basal and squamous cell skin cancers and melanoma to sunlight exposure. Some studies have shown possible links of sunlight exposure to Merkel cell carcinoma and melanoma of the eye. People who use tanning beds/booths have been shown to have a higher instance of melanoma and basal and squamous cell skin cancers, especially when they started tanning before the age of 25. Fortunately, when discovered early enough basal cell cancer and squamous cell cancer are almost always curable. Sunburns play a strong role in the development of melanoma and this is the most dangerous of the skin cancers because it has the ability to spread to other organs very rapidly if it is not treated early.
UV RADIATION AND YOUR EYES:
UV rays can damage all structures of the eye. The front surface of the eye absorbs 99% of UV radiation. Cataracts, corneal damage, macular degeneration and eye cancers take years to develop and each time we are enjoying the sunshine without eye protection, we increase our risks of eye disease leading to a decrease in or loss of vision. Additionally, those who have spent long hours in the midday sun, such as farmers, skiers, swimmers, surfers and fishermen, are more likely to develop growths on the conjunctiva of the eye called pterygium. The eyelid skin is the thinnest skin on our bodies and UV damage can leave us with dryness, wrinkles, loss of skin elasticity and mottled pigmentation, as well.
WHAT YOU CAN DO TO REDUCE YOUR RISKS:
When outside, try to stay in the shade, especially during midday hours.
Wear UV-blocking sunglasses; choose 100% UV or UV400 protection, or glasses that block both UVA and UVB rays.
Protect your skin with clothing which covers your arms and legs, and a hat to protect your head, face and neck.
Use sunscreen to help protect exposed skin.
SUNLIGHT AND YOUR HEALTH:
Healthy exposure to sunlight can have positive effects on our overall health as long as we protect ourselves against the damaging effects of UV radiation. In fact, our bodies require some natural light every day to help maintain good and restful sleep. There are light-sensitive cells in our eyes which play an important role in the body’s natural wake-sleep cycles, which can be important as we age and become more prone to insomnia. Your body also makes Vitamin D when it is exposed to the sunlight. Vitamin D helps to promote strong bones and may help to prevent some cancers.
Resources:
American Cancer Society - Ultraviolet Radiation
American Cancer Society - Be Safe in the Sun
EPA - UV Radiation and Sun Exposure
American Academy of Ophthalmology - The Sun, UV Light and Your Eyes