60. வெயிலோடு விளையாடி.. வெயிலோடு உறவாடி.. :
கப்பி பயTHE SUN, UV, AND YOU
While some exposure to sunlight is enjoyable, too much can be dangerous, causing immediate effects like blistering sunburns and longer-term problems like skin cancer and cataracts.
Overexposure also causes wrinkling and aging of the skin, and scientists are concerned that UV may even impair the human immune system.
UV RADIATION
The sun gives out energy over a broad spectrum of wavelengths. Ultraviolet (UV) radiation, which has a shorter wavelength than either visible blue or violet light, is responsible for sunburn and other adverse health effects. Fortunately for life on earth, stratospheric ozone screens most harmful UV radiation. However, what gets through the ozone layer can cause a number of problems, particularly for people who spend substantial time outdoors:
skin cancer
immune suppression
cataracts
premature aging of the skin
Because of these adverse health effects, you should limit your exposure to UV radiation and protect yourself when working, playing or exercising outdoors.
OZONE DEPLETION
The ozone layer forms a thin shield in the stratosphere, protecting life on earth from the sun's harmful ultraviolet (UV) rays. In the 1980s, scientists began accumulating evidence that the ozone layer was being depleted. Depletion of the ozone layer can result in increased UV radiation reaching the earth's surface, which can lead to greater chance of overexposure to UV and the consequent health effects, including skin cancer, cataracts, and immune suppression
HOW STRATOSPHERIC OZONE PROTECTS US
Ozone is a naturally occurring gas found in the earth's atmosphere that absorbs certain wavelengths of the sun's UV radiation. Ozone is concentrated in a part of the atmosphere called the stratosphere. Stratospheric ozone is most concentrated between 6-30 miles above the earth's surface.
Ozone is formed when oxygen molecules absorb UV radiation and split apart into two oxygen atoms (O), which combine with other oxygen molecules (02), to form ozone molecules (03). Ozone is also broken apart as it absorbs UV radiation. In this way, UV helps sustain the natural balance of ozone in the stratosphere, while ozone in turn absorbs UV, protecting life on earth from harmful radiation.
HOW OZONE IS DEPLETED
Chlorofluorcarbons (CFCs) are used widely in industry and elsewhere as refrigerants, insulating foams, and solvents. They migrate into the upper atmosphere after use. Because they are heavier than air, they have to be carried by air currents into the stratosphere, a process that can take as long as 5 to 10 years. These chemicals absorb UV radiation, break apart, and react with ozone, taking one oxygen atom away and forming highly reactive chlorine monoxide. Chlorine monoxide (C 0) in turn breaks down 03 again by pulling away a single oxygen atom, creating two 02 molecules, and allowing the C to move freely to another ozone molecule. In this way each chlorine atom acts as a catalyst, repeatedly combining with and breaking apart as many as 100,000 ozone molecules during its stratospheric life.
Other compounds also damage the ozone layer in much the same way as do CFCs. These ozone-depleting substances include pesticides such as methyl bromide, halons used in fire extinguishers, and methyl chloroform used in industrial processes.
WHAT IS BEING DONE ABOUT OZONE DEPLETION
Countries around the world have recognized the threats posed by ozone depletion and have responded by adopting the Montreal Protocol on Substances That Deplete the Ozone Layer. Parties to this treaty, including the United States, are phasing out the production of ozone-depleting substances.
EFFECT OF OZONE LAYER DEPLETION ON UV RADIATION LEVELS
Scientists predict that CFC levels should peak by the turn of the century and should fall to 1979 levels between the years 2020 and 2050. As international control measures reduce the release of CFC's and other ozone depleting substances, the natural atmospheric process will repair the ozone layer. Until that time, we can expect increased levels of UV at the Earth's surface. These increased UV radiation levels can lead to a greater chance of overexposure to UV radiation and the consequent health effects.
ACTION STEPS FOR SUN PROTECTIONTOO MUCH SUNLIGHT CAN BE DANGEROUS...
Excessive sun exposure can result in painful sunburn, but can also lead to other serious health problems, including melanoma, a life-threatening form of skin cancer. Melanoma is one of the fastest growing forms of cancer.
BE SUN WISE
Protecting yourself from overexposure to UV radiation is simple if you take the precautions listed below.
Wear Sunglasses That Block 99-100% of UV Radiation
Sunglasses that provide 99-100% UVA and UVB protection will greatly reduce sun exposure that can lead to cataracts and other eye damage. Check the label when buying sunglasses.
Wear a Hat
A hat with a wide brim offers good sun protection to your eyes, ears, face, and the back of your neck - areas particularly prone to overexposure to the sun.
Protect Other Areas Of Your Body With Clothing During Prolonged Periods in the Sun
Tightly-woven, loose-fitting clothes are best, but any clothing is better than none at all.
Always Use a Sunscreen When Outside on a Sunny Day
A sunscreen with a Sun Protection Factor (SPF) of at least 15 blocks most harmful UV radiation. Apply sunscreen liberally and reapply every two hours when working, playing, or exercising outdoors. Even waterproof sunscreen can come off when you towel off sweat or water. Children under six months of age should never have sunscreen applied to their skin, but should be protected by avoiding too much time outdoors.
Avoid the Midday Sun As Much As Possible
The sun's UV rays are strongest between 10 a.m. and 4 p.m. To the
extent you can, limit exposure to the sun during these hours.
Avoid Sunlamps and Tanning Parlors
Sunbeds damage the skin and unprotected eyes and are best avoided entirely.
SPECIAL CONSIDERATIONS FOR CHILDREN
Although many of the sun's worst effects do not appear until later in life, recent medical research has shown that it is very important to protect children and teenagers from overexposure to UV radiation. The majority of most people's sun exposure occurs before age 20, and studies increasingly suggest a link between early exposure and skin cancer as an adult.
HELPING CHILDREN BE SUN WISE
Take special care with children, since they spend more time outdoors than adults and can burn more quickly. The precautions described in this booklet can help ensure that the children around you avoid UV-related health problems, both now and later in life. Started early and followed consistently, each of these steps will become an easy, accepted habit, no more bothersome than fastening seatbelts every time you drive the car.
FOR MORE INFORMATION
To learn more about the UV Index and how to protect yourself from overexposure to the sun's UV rays, call EPA's Stratospheric Ozone Hotline at (800) 296-1996. Hotline staff can supply you with fact sheets and other useful information.
http://www.epa.gov/
A.M Ante meridiem ( latin word) - Before noon - முற்பகல்
8- இப்போ கலர் அடிக்கிற போட்டி.. பென்சில் கலர், க்ரயோன்ன்னு என்ன இருக்கோ ஆதை உபயோகிச்சு கலர் அடிங்க. இது எப்படி இருக்கு?
