Some UV exposure is essential for good health. It stimulates vitamin D production in the body. In medical practice, one example is UV lamps can be used for treating psoriasis (a condition causing itchy, scaly red patches on the skin). Show Excessive exposure to ultraviolet radiation is associated with different types of skin cancer, sunburn, accelerated skin aging, as well as cataracts and other eye diseases. The severity of the effect depends on the wavelength (see Figure 2), intensity, and duration of exposure. Effect on the skinThe shortwave UV radiation (UV-C) poses the maximum risk. The sun emits UV-C but it is absorbed in the ozone layer of the atmosphere before reaching the earth. Therefore, UV-C from the sun does not affect people. Some man-made UV sources also emit UV-C. However, the regulations concerning such sources restrict the UV-C intensity to a minimal level and may have requirements to install special guards or shields and interlocks to prevent exposure to the UV. The medium wave UV (UV-B) causes skin burns, erythema (reddening of the skin) and darkening of the skin. Prolonged exposures increase the risk of skin cancer.  Figure 2 - Relative sensitivity of the eye and the skin to UV radiation of different wavelengths. Longwave UV radiation (UV-A) accounts for up to 95% of the UV radiation that reaches the earth's surface. Although UV-A is less intense than UV-B, it is more prevalent and can penetrate deeper into the skin layers, affecting the connective tissue and blood vessels, which results in premature aging. Certain chemicals and medications act as photosensitizing agents and enhance the effect of UV radiation from sunlight or other sources. Such agents include thiazide diuretics (drugs which cause excessive urine production), drugs used in the treatment of high blood pressure, certain antibiotics (tetracyclines, sulfonamides), cosmetics, and thiazine tranquilizers. These are just a few examples; this is not intended to be a comprehensive list. However, it is important to know that these photosensitizing effects can occur in case people are exposed to UV radiation at work. For example, an inexperienced welder, who was taking a phenothiazine anti-depressant drug, suffered damage in both eyes in the part of the retina that absorbs short wavelength light (bilateral maculopathy). He began complaining of eye problems a day after he was arc welding for two minutes without wearing any eye protection. This damage, that fortunately was reversible after several months, occurred because the drug he was taking sensitized him to the UV radiation to which he was exposed. Various plants such as carrot, celery, dill, fig, lemon and some types of weeds are known to cause photosensitivity. Exposure to fluids from these plants, especially if crushed, followed by exposure to sunlight can cause dermatitis. Citrus fruit handlers and vegetable harvesters, gardeners, florists and bartenders are at risk for experiencing dermatitis following exposure to certain plants and then to sunlight (phytophotodermatitis). Coal tar and creosote are examples of photosensitizing agents in the workplace. Effects of repeated exposures (chronic effects) include skin aging and skin cancer. There is a strong causal link between skin cancer and prolonged exposure to solar UV and from artificial sources. Effect on the eyesThe eyes are particularly sensitive to UV radiation. Even a short exposure of a few seconds can result in a painful, but temporary condition known as photokeratitis and conjunctivitis. Photokeratitis is a painful condition caused by the inflammation of the cornea of the eye. The eye waters and vision is blurred. Conjunctivitis is the inflammation of the conjunctiva (the membrane that covers the inside of the eyelids and the sclera, the white part of the eyeball); (see Figure 3) which becomes swollen and produces a watery discharge. It causes discomfort rather than pain and does not usually affect vision. Figure 3 - The eye Examples of eye disorders resulting from UV exposure include "flash burn", "ground-glass eye ball", "welder's flash" and "snow blindness" - depending on the source of the UV light causing the injury. The symptoms are pain, discomfort similar to the feeling of sand in the eye and an aversion to bright light. The eyes are most sensitive to UV radiation from 210 nm to 320 nm (UV-C and UV-B). Maximum absorption by the cornea occurs around 280 nm. Absorption of UV-A in the lens may be a factor in producing cataract (a clouding of the lens in the eye). Taking steps to protect yourself from the sun is a year-round responsibility. Protect yourself and others from the sun with shade, a shirt, or sunblock (SPF 15+) all year long. Ultraviolet (UV) radiation is a form of non-ionizing radiation that is emitted by the sun and artificial sources, such as tanning beds. While it has some benefits for people, including the creation of Vitamin D, it also can cause health risks.
Types of UV Radiation RaysUV radiation is classified into three primary types: ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC), based on their wavelengths. Almost all of the UV radiation that reaches earth is UVA though some UVB radiation reaches earth. UVA and UVB radiation can both affect health but UVA penetrates deeper into the skin and is more constant throughout the year.
*nm= 0.000000001 meters or 1×10-9 meters Benefits
Vitamin D helps the body absorb calcium and phosphorus from food and assists bone development. The World Health Organization (WHO) recommends 5 to 15 minutes of sun exposure 2 to 3 times a week. Risks
Skin cancer is the most common cancer in the United States. The two most common types of skin cancer are basal cell cancer and squamous cell cancer. Typically, they form on the head, face, neck, hands, and arms because these body parts are the most exposed to UV radiation. Most cases of melanoma, the deadliest kind of skin cancer, are caused by exposure to UV radiation. Anyone can have harmful health effects from UV radiation, but the risks increase in people who:
Sunscreen and sunglasses can be used to protect you from UV radiation. To protect yourself from UV radiation:
Please visit CDC’s Radiation and Your Health website for more information. What are 5 harmful effects of UV rays on humans?Health Effects of UV Radiation. Skin cancer (melanoma and nonmelanoma). Premature aging and other skin damage.. Cataracts and other eye damage.. Immune system suppression.. Which skin is more susceptible to UV?People with light skin are much more likely to have their skin damaged by UV rays (and to get skin cancer), but darker-skinned people, including people of any ethnicity, can also be affected. For some people, the skin tans when it absorbs UV rays.
What type of UV rays cause skin aging and wrinkles?UVB rays are shorter than UVA rays, and are the main culprit behind sunburn. The UVA rays, with their longer wavelength, are responsible for much of the damage we associate with photoaging. UVA rays penetrate deep into the dermis, where they damage the collagen fibers.
How do UV rays contribute to skin aging?The sun's ultraviolet light can cause major damage to the skin. The outer layer of the skin has cells that contain the pigment melanin. Melanin protects skin from the sun's ultraviolet rays. These can burn the skin and reduce its elasticity, leading to premature aging.
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Which skin changes due to aging are caused by chronic exposure to ultraviolet rays select all that apply?
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