For nearly a billion years, ozone molecules in the atmosphere have protected life on UV Rays and Eye Damage from the effects of ultraviolet rays. The ozone layer resides in the stratosphere and surrounds the entire Earth. Sun is partially absorbed in this layer.
As a result, the amount of UV-B reaching Earth’s surface is greatly reduced. In the past 60 years or so human activity has contributed to the deterioration of the ozone layer. Only 10 or less of every million molecules of air are ozone. Spring in the southern hemisphere is from September through November. As winter arrives, a vortex of winds develops around the pole and isolates the polar stratosphere.
Chemical reactions on the surfaces of ice crystals in the clouds release active forms of CFCs. This has come to be called the Antarctic ozone hole. In spring, temperatures begin to rise, the ice evaporates, and the ozone layer starts to recover. In 1984 British Antarctic Survey scientists, Joesph Farman , Brian Gardiner, and Jonathan Shanklin, discovered a recurring springtime Antarctic ozone hole .
The ozone “hole” is really a reduction in concentrations of ozone high above the earth in the stratosphere. The ozone hole is defined geographically as the area wherein the total ozone amount is less than 220 Dobson Units. After a series of rigorous meetings and negotiations, the Montreal Protocol on Substances that Deplete the Ozone Layer was finally agreed upon on 16 september 1987 at the Headquarters of the International Civil Aviation Organization in Montreal. ODP is a number that refers to the amount of ozone depletion caused by a chemical substance. Consumption of ozone depleting substances has largely been reduced in the past 20 years. This Website is a project of the The Ozone Hole Inc. The eye occupies less than 2 per cent of the whole body surface area, but it represents the sole organ system to allow the penetration of visible light deep into the human body.
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The eye is recessed within the anatomy of the head and shielded well by the brow ridge, the eyebrows and the eyelashes. However, these anatomical adaptations are of limited use in UV protection under extreme conditions such as sunbed use or strong ground reflection from snow, water and sand. Constriction of the pupil, closure of the eyelids and the squinting reflex minimize the penetration of the sun’s rays into the eye. UV radiation exposure may still be high. Therefore, the effectiveness of these natural defences in protecting against UV damage is limited. These inflammatory reactions may be compared to a sunburn of the very sensitive skin-like tissues of the eyeball and eyelids and usually appear within a few hours of exposure.
An extreme form of photokeratitis is snow blindness. 80 per cent of incident UV radiation. These extreme UV levels kill the outer cells of the eyeball leading to blindness. Snow blindness is very painful when the dead cells are being shed. This growth of the conjunctiva on the surface of the eye is a common cosmetic blemish and is probably linked to prolonged UV exposure. Pterygium may extend over the centre of the cornea and thereby reduce vision.
It also has a tendency to become inflamed. Even though it can be removed by surgery, the outgrowth tends to recur. Proteins in the eye’s lens unravel, tangle and accumulate pigments which cloud the lens and eventually lead to blindness. Even though cataracts appear to different degrees in most individuals as they age, they appear to be enhanced by exposure to UVB. Cataracts can be surgically removed and an artificial lens or other means of optical correction can restore vision.
Every year some 16 million people in the world suffer from blindness due to a loss of transparency in the lens. WHO estimates suggest that up to 20 per cent of cataracts may be caused by overexposure to UV radiation and are therefore avoidable. Melanoma is the most frequent malignant cancer of the eyeball and sometimes requires surgical removal. A common location for basal cell carcinoma is on the eyelids.
Are there beneficial effects of UV radiation? What are the effects of UV on the skin? What are the effects of UV on the eye? Does UV interact with the immune system? I still need to be careful? Ritter was a German physicist born on December the 16th, 1776 in Samitz bel Haynau Silesia, now Poland.
He devoted his efforts to studying electricity and electrochemistry. However his main discovery was the ultraviolet region of the spectrum. In 1801 he conducted experiments with silver chloride and a prism. He projected a beam of sunlight through the prism, which split the beam into the colors of the spectrum. He them put chloride in each color to see the outcome. Solar Ultraviolet or UV rays make up part of the electromagnetic or photonic spectrum of light and radiant energy.
Part of this spectrum is broken down into wavelengths and is measured by nanometers or nm, for short. The electromagnetic spectrum within the wavelength region ranges from the vacuum ultraviolet to the far infrared. We cannot see ultraviolet light and it is shorter in wavelength than visible light. For most of us, however, the sun is the primary source of UV.
The effects of UV radiation on earth’s ecosystems are not completely understood. Even isolating the effects of UVA versus UVB is somewhat arbitrary. All UV radiation can be damaging. This knowledge has prompted many manufacturers of sun screen and sunglasses to offer products that protect against both UVA and UVB wavelengths. To determine UV ray levels an instrument capable of measuring these “invisible” rays must be used. UV rays, for example, are necessary for our body to produce vitamin D, a substance that helps strengthen bones and safeguards against diseases such as Rickets.
Some scientists have shown that Vitamin D lowers the risk of getting some kinds of internal cancer, like colon cancer. UV light is also used as a therapy for psoriasis, a condition in which the skin sheds its cells too quickly, resulting in itchy, scaly patches on various parts of the body. When exposed to ultraviolet rays, the growth of the skin cells is slowed, relieving the symptoms. UV rays are also used in various commercial functions, such as disinfecting fish tanks and sterilizing medical equipment. Animal life makes their own use of these wavelengths too—certain animals can actually see ultraviolet light, and use it to their advantage. Bees use the reflection of UV off of flower petals to guide their pollen collecting. Though ultraviolet rays do have a purpose, one must not use this information as a validation for their sunbathing habits.
The dangers of UV exposure are real, and public ignorance concerning these matters could lead to increased health problems in the future. One of the most common effects of UV exposure is “erythema”, also known as sunburn. Sunburn occurs when skin cells are damaged by the absorption of energy from UV rays. To compensate for this injury, the skin sends extra blood to the damaged skin in an attempt to repair it—thus accounting for the redness that is associated with sunburn. Another effect of ultraviolet rays on the skin is photoaging. UV exposure—so though your tan may look good now, you could be paying your dues in wrinkles later. In order to inform the public about the intensity of UV radiation the UV Index was invented and is now published in newspapers and on TV.
The definition of the UV Index is the same throughout the world, so it’s a great way to learn about the UV hazards at your travel destinations. The Index is a simple number. A common misconception among the public is that if the damage isn’t visible, no damage has been done. The only way to dispute this is to observe the long term effects of a stimulus. One of these effects has been identified to be skin cancer.
The American Cancer Society has predicted that in the year 2001, approximately one million new cases of non-melanoma type skin cancers will be diagnosed, along with an additional 51,400 melanoma cases. There are three basic types of skin cancer: melanoma, basal cell carcinoma, and squamous cell carcinoma. Basal and squamous cell carcinoma make up the most common and less dangerous forms, called non-melanoma cancers. The causes of malignant melanoma are much less defined. Some suspect that there is a relationship between UV exposure and melanoma rates, but there are varying theories.
Some scientists have developed a theory that UV-A radiation is much more effective in causing melanoma than assumed previously. If this were the case, then many sunscreens currently available offer only very little protection against melanoma, as they mostly block UV-B, and not UV-A. One of the best ways to protect against the dangers of melanoma is to catch it before it’s too late. Melanoma has a high cure rate if it is caught early on. Does one half of the mole look like the other?
Are the edges smooth and regular, or are they crooked? Is it larger than one cm? Moles that develop later in life should also be a source of concern. Most benign moles have been present since childhood. However, it is possible for childhood moles to become malignant. Because of this, changes in the appearance of any mole should be noted. Australian Skin Cancer Australians suffer the highest rates of skin cancer in the world.
Each year, around 1,200 Australians die from what is an almost totally preventable disease. Australia are higher than in Europe, even during summer. Being located close to the ozone hole over the Antarctic means much higher, more severe levels of UV radiation get through to ground level. During summer, the earth’s orbit brings Australia closer to the sun than Europe during its summer, resulting in an additional seven per cent solar UV intensity. Since then, attitudes towards tanning and sun protection have changed dramatically.
Australians have realised the pitfalls of their sun-loving, outdoor lifestyle and are taking preventative measures to reduce their risk of sun damage and skin cancer. Consequently, skin cancer deaths have slowed and for females, have even started to decline. More Australians are detecting skin cancers early, increasing their chances of surviving the disease. Ultraviolet rays can be reflected towards the eyes by certain substances, such as sand and snow. When this happens, the amount of UV rays the eyes are exposed to is increased. This fact is the basis of the condition photokeratitis, also known as snow blindness. Photokeratitis is a sunburn of the cornea, and usually recedes within one to two days.
It occurs when the eyes are exposed to large quantities of UV light in a short amount of time. It is more difficult to isolate the exact amount of damage that UV imposes on the eye over a long period of time, as the body has its own built-in defense against harmful rays. If you were to try to look up at the sun, you would find that you would not be able to do so for any length of time. Your eyes would naturally start to close. This effect is also noticed on especially bright days, displayed in the form of squinting. Even though some species respond positively, extensive tests in several countries have shown that hundreds of species of plants and animals display negative effects from an increase in UV radiation. Another issue that may seem more relevant to the human population is the effect of UV on plants and food crops.
Greater exposure of plant life to UV-B can result in a decrease in production rates, meaning less food available world-wide. Throughout the world efforts are being made to increase the level of UV resistance in staple crops, such as rice, where some species are extremely sensitive to UV radiation, and other species of rice can withstand a great increase. With this knowledge, scientists can find the most effective and economical species to use in rice farming, thereby increasing the UV resistance of much of the world’s food supply. Credit:NOAA,NASA, EPA, National Science Foundation Polar Programs UV Monitoring Network Maintained by Biospherical Instruments Inc. This Website is a project of the The Ozone Hole Inc.
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Enter the characters you see below Sorry, we just need to make sure you’re not a robot. An official website of the United States government. We’ve made some changes to EPA. If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot. This Web page provides an overview of the major health problems linked to overexposure to UV radiation.
Skin Cancer Each year, more new cases of skin cancer are diagnosed in the U. One in five Americans will develop skin cancer in their lifetime. One American dies from skin cancer every hour. Unprotected exposure to UV radiation is the most preventable risk factor for skin cancer. Melanoma Melanoma, the most serious form of skin cancer, is now one of the most common cancers among adolescents and young adults ages 15-29.
While melanoma accounts for about three percent of skin cancer cases, it causes more than 75 percent of skin cancer deaths. UV exposure and sunburns, particularly during childhood, are risk factors for the disease. Nonmelanoma Skin Cancers Non-melanoma skin cancers are less deadly than melanomas. Nevertheless, they can spread if left untreated, causing disfigurement and more serious health problems.
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There are two primary types of non-melanoma skin cancers: basal cell and squamous cell carcinomas. If caught and treated early, these two cancers are rarely fatal. Basal cell carcinomas are the most common type of skin cancer tumors. They usually appear as small, fleshy bumps or nodules on the head and neck, but can occur on other skin areas. Basal cell carcinoma grows slowly, and it rarely spreads to other parts of the body. It can, however, penetrate to the bone and cause considerable damage. Squamous cell carcinomas are tumors that may appear as nodules or as red, scaly patches.
This cancer can develop into large masses, and unlike basal cell carcinoma, it can spread to other parts of the body. Premature Aging and Other Skin Damage Other UV-related skin disorders include actinic keratoses and premature aging of the skin. Actinic keratoses are skin growths that occur on body areas exposed to the sun. Although premalignant, actinic keratoses are a risk factor for squamous cell carcinoma. Chronic exposure to the sun also causes premature aging, which over time can make the skin become thick, wrinkled, and leathery. Since it occurs gradually, often manifesting itself many years after the majority of a person’s sun exposure, premature aging is often regarded as an unavoidable, normal part of growing older.
However, up to 90 percent of the visible skin changes commonly attributed to aging are caused by the sun. Cataracts and Other Eye Damage Cataracts are a form of eye damage in which a loss of transparency in the lens of the eye clouds vision. If left untreated, cataracts can lead to blindness. Research has shown that UV radiation increases the likelihood of certain cataracts. Although curable with modern eye surgery, cataracts diminish the eyesight of millions of Americans and cost billions of dollars in medical care each year. All of these problems can be lessened with proper eye protection. Look for sunglasses, glasses or contact lenses if you wear them, that offer 99 to 100 percent UV protection.
Immune Suppression Scientists have found that overexposure to UV radiation may suppress proper functioning of the body’s immune system and the skin’s natural defenses. For example, the skin normally mounts a defense against foreign invaders such as cancers and infections. But overexposure to UV radiation can weaken the immune system, reducing the skin’s ability to protect against these invaders. Skin cancer is the most common form of cancer in the United States. Department of Health and Human Services and the World Health Organization. But seven years later, it was back. This time the melanoma showed up as a larger black mole, which grew to the size of a quarter over a weekend.
I called my doctor immediately and had two more surgeries to remove the melanoma. Telling my father that his only child had melanoma was one of the hardest things I’ve ever had to do. He worried that he would never walk his daughter down the aisle, but this summer he finally had the chance! After nearly 10 surgeries in total, I have been cancer-free now for 5 years. Since my diagnoses, I have been vigilant about checking for skin changes and wearing sunscreen when I’m outdoors. I’ve also been inspired to spread the word about skin cancer prevention and the power of early detection by telling my story.
If you find a suspicious mole, call your doctor right away! Contact Us to ask a question, provide feedback, or report a problem. The UV Index is designed as an open-ended linear scale, directly proportional to the intensity of UV radiation that causes sunburn on human skin. An index of 0 corresponds to zero UV radiation, as is essentially the case at night. While the UV Index can be calculated from a direct measurement of the UV spectral power at a given location, as some inexpensive portable devices are able to approximate, the value given in weather reports is usually a prediction based on a computer model. When the UV Index is presented on a daily basis, it represents UV intensity around the sun’s highest point in the day, called solar noon, halfway between sunrise and sunset.
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This typically occurs between 11:30 and 12:30, or between 12:30 and 13:30 in areas where daylight saving time is being observed. 5 is approximately equivalent to a half-hour at index 10, although other factors like the body’s ability to repair damage over a given time period could detract from the validity of this assumption. The UV Index is a number linearly related to the intensity of sunburn-producing UV radiation at a given point on the earth’s surface. To illustrate the spectrum weighting principle, the incident power density in midday summer sunlight is typically 0. Note the huge absorption that has already taken place in the atmosphere at short wavelengths. The erythemal weighting factors applied to these figures are 1. After sporadic attempts by various meteorologists to define a “sunburn index”, and amid growing concern about ozone depletion, Environment Canada scientists James B.
Wardle developed the modern UV Index in Toronto, Ontario. 29, 2003, a world-record ground-level UV index of 43. 3 was detected at Bolivia’s Licancabur volcano, though other scientists dispute readings higher than 26. In 2005, the United States and Australia launched the UV Alert. While the two countries have different baseline UV intensity requirements before issuing an alert, their common goal is to raise awareness of the dangers of over-exposure to the sun on days with intense UV radiation. A UV Index reading of 0 to 2 means low danger from the sun’s UV rays for the average person.
Bright surfaces, such as sand, water and snow, will increase UV exposure. A UV Index reading of 3 to 5 means moderate risk of harm from unprotected sun exposure. Stay in shade near midday when the sun is strongest. If outdoors, wear sun protective clothing, a wide-brimmed hat, and UV-blocking sunglasses. 2 hours, even on cloudy days, and after swimming or sweating. A UV Index reading of 6 to 7 means high risk of harm from unprotected sun exposure.
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Protection against skin and eye damage is needed. Reduce time in the sun between 10 a. If outdoors, seek shade and wear sun protective clothing, a wide-brimmed hat, and UV-blocking sunglasses. A UV Index reading of 8 to 10 means very high risk of harm from unprotected sun exposure. Take extra precautions because unprotected skin and eyes will be damaged and can burn quickly. Minimize sun exposure between 10 a. A UV Index reading of 11 or more means extreme risk of harm from unprotected sun exposure.
Take all precautions because unprotected skin and eyes can burn in minutes. Try to avoid sun exposure between 10 a. The intensity of UV radiation reaching the surface of the earth depends on the angle of the sun in the sky. 12:00 on clocks or 13:00 during daylight saving time.
Likewise, UV intensity can be higher or lower for surfaces at different angles to the horizontal. UV intensity can nearly double with reflection from snow or other bright surfaces like water, sand, or concrete. The recommendations given are for average adults with lightly tanned skin. Because of the way the UV Index is calculated, it technically expresses the risk of developing sunburn, which is caused mostly by UVB radiation. Environmental Protection Agency, a helpful method to estimate the amount of UV radiation people are exposed to is by observing the length of their shadow. A taller shadow may mean a lower UV exposure while a shorter one could translate to exposure to higher levels of UV radiation.
The UV Index: Definition, Distribution and Factors Affecting It. Fast simulation tool for ultraviolet radiation at the Earth’s surface. A reference action spectrum for ultraviolet induced erythema in human skin. How Is the UV Index Calculated? Archived 2010-06-13 at the Wayback Machine. The Canadian Ozone Watch and UV-B advisory programs.