1. Ultraviolet Radiation & the eye
Diana Alrabe

2. Protecting Yourself from UV Radiation
SUN SAFETY
Protecting Yourself from UV Radiation

3. Ultraviolet Radiation - UV
What is Ultraviolet Radiation?

4. Ultraviolet Radiation - UV
The sun is the energy source that sustains all life on earth.
Ultraviolet Radiation (UV) is simply one form of energy coming from the sun.

5. What is ultraviolet radiation?
Ultraviolet (UV) radiation is similar to visible light in all physical aspects, except that it does not enable us to see things. The light that enables us to see things is referred to as visible light and is composed of the colors we see in a rainbow. The ultraviolet region starts right after the violet end of the rainbow.

6. In scientific terms, UV radiation is electromagnetic radiation just like visible light, radar signals and radio broadcast signals. Electromagnetic radiation is transmitted in the form of waves. The waves can be described by their wavelength or frequency and their amplitude (the strength or intensity of the wave). Wavelength is the length of one complete wave cycle. For radiation in the UV region of the spectrum, wavelengths are measured in nanometers (nm), where 1 nm = one millionth of a millimeter.

7. Different wavelengths of electromagnetic radiation cause different types of effects on people. For example, gamma rays are used in cancer therapy to kill cancerous cells and infrared light can be used to keep you warm.
UV radiation has :
shorter wavelengths (higher frequencies) compared to visible light but have longer wavelengths (lower frequencies) compared to X-rays.
UV radiation is divided into three wavelength

9. What are some sources of ultraviolet radiation?
Sunlight is the greatest source of UV radiation. Man-made ultraviolet sources include several types of UV lamps, arc welding, and mercury vapour lamps.
UV radiation is widely used in industrial processes and in medical and dental practices for a variety of purposes, such as killing bacteria, creating fluorescent effects, curing inks and resins, phototherapy and suntanning. Different UV wavelengths and intensities are used for different purposes.

10. Some Devices Emitting UV Radiation
Bactericidal lamps Black light lamps Carbon, xenon and other arcs Dental polymerizing equipment Fluorescence equipment Hydrogen and deuterium lamps
Metal halide lamps Mercury lamps Plasma torches Phototherapy lamps  Printing ink polymerizing equipment Welding equipment

11. What are some health effects of exposure to UV radiation?
Some UV exposure is essential for good health. It stimulates vitamin D production in the body. In medical practice, UV lamps are used for treating psoriasis (a condition causing itchy, scaly red patches on the skin) and for treating jaundice in new born babies.
Excessive exposure can damage the skin and the eyes. The severity of the effect depends on the wavelength, intensity, and duration of exposure.

12. Effect on the eyes
The 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);which becomes swollen and produces a watery discharge. It causes discomfort rather than pain and does not usually affect vision.

13. EYE EFFECT
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).

14. Ultraviolet Radiation - UV
Sunlight contains 3 types of UV rays…

15. Ultraviolet Radiation - UV
UVA—causes skin aging & wrinkles. Used in tanning beds. Colors skin and gives false sense of protection from the sun. UVA rays pass effortlessly through the ozone layer.

16. Ultraviolet Radiation - UV
UVB—causes sunburns, cataracts, immune system damage, skin cancer. Melanoma may be associated with severe UVB sunburns occurring before the age of 20. Most UVB rays are absorbed by the ozone layer.

17. Ultraviolet Radiation - UV
UVC—these rays are the most dangerous. Fortunately, these rays are blocked by the ozone layer and don’t reach the earth.

18. Ultraviolet Radiation - UV
Even on cloudy, cool, or overcast days, UV rays travel through the clouds and reflect off sand, water, snow, and even concrete.
Clouds and pollution don’t filter out UV rays, and can give a false sense of protection.
This “invisible sun” can cause unexpected sunburn and skin damage.

19. Ultraviolet Radiation - UV
The sun’s light is strongest when it is highest in the sky (normally from 10 AM to 4 PM).
UV rays are strongest during the summer.
UV intensity is greater at high altitudes. Skiers need to take extra care.

20. Ultraviolet Radiation - UV
The UV Index* predicts the next day’s UV levels on a scale.
*Developed by the National Weather Service and the EPA.
UV Index Number
Exposure Level
Minutes to Burn
0 to 2
Minimal 60
3 to 4
Low 45
5 to 6
Moderate 30
7 to 9
High 15
10+
Very high 10

21. Effects of UV Exposure
Sunburn

22. Effects of UV Exposure
Sunburn

23. Effects of UV Exposure
Sunburn develops when the amount of UV exposure is greater than the protection your skin’s melanin can provide.
The lighter your skin, the less melanin it has to absorb UV and protect itself.
All skin, no matter the color, thickens and hardens with continued sun exposure, resulting in wrinkles later in life.

24. Effects of UV Exposure
Eye Damage

25. Effects of UV Exposure
Spending long hours in the sun with no eye protection may increase your chance of developing cataracts.
Even low amounts of sunlight can increase the risk of eye disorders.
UVB damage to the eyes is cumulative, so it is never too late to start protecting your eyes.

26. Effects of UV Exposure
Skin Damage

27. Effects of UV Exposure
There are about 1.3 million new cases of skin cancer in the U.S. each year, resulting in about 9,800 deaths.
Melanoma is one type of skin cancer. It is the most common cancer among women between the ages of 25 and 29.

28. Effects of UV Exposure
Skin cancer is the most common of cancers and is largely preventable.
Increased outdoor leisure time, less clothing worn outdoors, and decreased ozone levels are partly to blame.

29. Effects of UV Exposure
“Sun damage” causes wrinkles, easy bruising, brown “liver” spots, and potentially, skin cancer.

30. Effects of UV Exposure
Scientists believe sunburns can alter the body’s immune system for up to 24 hours after exposure to the sun.
Repeated overexposure to UV radiation can cause more damage to the body’s immune system, even in people with dark skin.

31. Guidelines for Protection
Eye Protection

32. Guidelines for Protection
Sunglasses offer excellent protection.
Make sure the lenses are designed to block out 95% of UV.
Polarizing lenses and mirror finishes reduce glare, but have little effect in blocking the absorption of UV rays.

33. Guidelines for Protection
Tanning Protection

34. Guidelines for Protection
Sunscreen doesn’t offer 100% protection.
SPF 30+ sunscreen blocks 96% of UV; SPF 15+ blocks out 93%.
In addition to sunscreen, wear a hat, sunglasses, more clothing, and seek shade.

35. Guidelines for Protection
Using SPF 30+ instead of SPF 15+ does not mean you can safely double your time in the sun.
Apply sunscreen 20 minutes before going outside. Don’t rub it in—a light film should stay visible.

36. Guidelines for Protection
Protective Clothing

37. Guidelines for Protection
Appropriately designed clothing is great for protecting you from the sun.

38. Sun Safety