Student's Guide - Answers to Quiz
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1. What does UV stand for?
UV stands for ultraviolet.

2. Where does UV come from?
UV radiation comes mainly from the sun, although it can be artificially created on earth.

3. How many atoms of oxygen bond to create one molecule of ozone?
Three atoms bond together.

4. Where is most of the earth's "good ozone" located?
It is found in the stratosphere, around 10-50 km high.

5. Where is most of the earth's "bad ozone" located?
It is found in the troposphere, close to the surface of the earth, under 5 km high.

6. What does ozone do?
Located in the stratosphere, ozone is important for blocking out much of the UV radiation that is emitted by the sun. Lower, in the troposphere, ozone is a component of smog, and is responsible for breathing difficulties and other ailments.

7. What does CFC stand for?
CFC stands for chlorofluorocarbon.

8. What are CFCs?
Any of several organic compounds composed of carbon, fluorine, chlorine, and hydrogen. Some CFCs are manufactured under the trade name freon. Developed during the 1930s, CFCs found wide application after World War II. These "halogenated hydrocarbons" have been used extensively as aerosol-spray propellants, refrigerants, solvents, and foam-blowing agents. They are well-suited for these and other applications because they are nontoxic and nonflammable and can be readily converted from a liquid to a gas and vice versa.

9. Where do CFCs come from?
CFCs are man-made substances, which account for much of the damage to the ozone layer. CFCs were first used to clean electronic circuit boards, and as time progressed, were used in aerosols and coolants, such as refrigerators and air conditioners.

10. Name some conditions that would result in a high amount of UV in your area.
Noontime in summer, when the sun is high in the sky. Low cloud cover. Reflective ground cover like sand or snow. High altitude.

11. What are some of the effects of UV on humans?
UV can cause tans and sunburns after a short while, and with prolonged exposure, it can cause wrinkles, faster photo aging, and even different types of skin cancer.

12. Sunscreen is the only way to protect yourself from UV radiation. - T or F
False, there are many ways to protect yourself from UV radiation. It is better to wear protective clothing than the application of sunscreen alone.

13. List some of the ways to protect yourself from UV radiation.
Wear UV blocking sunglasses. A thick meshed, wide-brimmed hat. Thick meshed clothing. 30 SPF or greater sunscreen. Try to stay in the shade. Stay out of the sun between 11 AM - 3 PM

14. About how many cases of skin cancer are reported yearly in the US?
About 1 million cases are reported yearly in the US.

15. What are some things that will make someone more susceptible to skin cancer?
If you have fair skin; or blond, red, or light brown hair. If you have lots of moles, irregular moles, or large moles. If you were previously treated for skin cancer. If you work indoors all week and then try to catch up on your tan on weekends. If you have freckles and burn before tanning.  If you have a family history of skin cancer, especially melanoma. If you live or vacation at high altitudes (ultraviolet radiation from the sun increases 4% to 5% for every 1,000 feet above sea level).

16. Which is the most dangerous kind of skin cancer?
Malignant melanoma is the most dangerous type of skin cancer.

17. What type of UV radiation does most sunscreen protect against?
UV-B. Some sunscreens also protect against UV-A, but, in general, all sunscreens protect against UV-B.

18. What unit of measurement is used to measure the relative thickness of the ozone layer?
Measurements of the ozone layer are made in Dobson Units.

19. Clouds completely block out UV radiation. - T or F
False, clouds can block some but not all of UV radiation. Puffy clouds close to the sun can even lead to increased UV.

20. You can find most of earth's ozone within 5 km of the surface of the earth. - T or F
False, most of earth's ozone is located in the stratosphere, 10-50 km above the surface of the earth.

21. About how many molecules of ozone are there per air molecule in the stratosphere?
There are about 3 molecules of ozone for every 10 million molecules of air in the stratosphere.

22. The ozone layer, if compacted together on the surface of the earth would be about 3 meters thick. - T or F
False, it would be about 3 mm thick.

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