Consider This 2.1 Ozone Levels Above Your Spot on Earth
How much protective ozone is above you? How does it compare with the amount of ozone above Antarctica?
a.NASA provides access to satellite data. Click on your location on the world map or enter your specific latitude and longitude to find the most recent data for total column ozone. Also request data for the same date and location for the last three years. Do you see any trend?
b. How do values at your location compare with those given for Antarctica on the same date each year?

Consider This 2.18 Geography of Skin Cancer
a. Which states in the United States have the highest incidence of melanoma?
b. Which states have the highest mortality rates from melanoma?
c. Offer some possible reasons why these two sets of states are not the same.
d. Alaska and Hawaii both have very low mortality rates from melanoma. What factors help account for this?

Consider This 2.19 Bronze by Choice—Tanning Salons
The indoor tanning industry maintains a constant public relations campaign that highlights positive news about indoor tanning, promoting it as part of a healthy lifestyle no matter the pigmentation of one's skin. Countering these claims are the studies published in scientific journals that support the view of dermatologists that there is no such thing as a "safe tan" for any skin type. Investigate at least two Web sites that present different points of view and list the specific claims made. Based on your findings, which criteria would you personally use to decide whether or not to go to an indoor tanning salon for health benefits?

Consider This 2.20 UV Index Forecasts
The UV Index indicates the amount of UV radiation reaching Earth's surface at solar noon (1 pm Eastern Standard Time)
a. The UV Index depends on the latitude, the day of the year, time of day, amount of ozone above the city, elevation, and the predicted cloud cover. How is the UV Index affected by each of these?
b. The UV Index forecast is available on the Web, compliments of the Environmental Protection Agency. Account for the range of values that you see on today's map of the United States.
c. Surfaces such as snow, sand, and water intensify your exposure to UV radiation, because they reflect it back at you. What outdoor activities might increase your risk from exposure?

Consider This 2.21 Protecting Your Eyes from UV Rays
Sunglasses make far more than a fashion statement. They can protect your eyes from harmful UV rays. What characteristics would you look for in sunglasses to be used when water skiing or sailing? Check out two or three manufacturers to find out what virtues of their products are stressed in their advertising for this use. What materials are used to make sunglasses for water sports? Did you find that the price of sunglasses was related to the amount of UV protection? Is the same protection available for those wearing prescription glasses? Would you purchase and wear the sunglasses you found through your research? Explain your choices.
Hint: Before investigating some sunglass manufacturers, the Mayo Clinic has some general information on UV protection you might find helpful.

Consider This 2.23 Up and Down the Latitudes
Use NASA's archive of satellite data on total column ozone levels to find data from 2004 to 2007 over the lower Northern Hemisphere latitudes. You may wish to coordinate your efforts with other students by each picking one year to research.
a. Obtain values of total column ozone levels at latitudes from +45° north to +0 (the equator) for September 15 of each year. Enter –90° west (roughly the middle of the United States ) as the longitude. Obtain readings 5° apart. Make a table of the stratospheric ozone values and compute the average.
b. Compare data over these 4 years with others in your class. Note that you may not always be able to use the average as a meaningful comparison, because satellite data may be missing at some latitudes.

Consider This 2.25 Northern Hemisphere Ozone Maps
Use the resources of NOAA's Climate Prediction Center or Environment Canada to find seasonal images of total ozone concentrations over the Northern Hemisphere. How do the ozone concentrations vary with the seasons? Do these match the seasonal variations for the Southern Hemisphere?

Sceptical Chymist 2.33 Black Market CFCs
A study reported in the May 2000 issue of Atmospheric Environment concluded that illegal trade in CFCs is only a "small threat" to ozone layer recovery. Although the Sceptical Chymist would like for this to be true, is it? Please provide some current information to either support or refute this statement.

Consider This 2.31 Montreal Protocol Ratification
a. How many nations have currently ratified the Montreal Protocol?
b. Does that number include India and China? If so, in what year did they do so?
c. Have the signatories to the Montreal Protocol also ratified the subsequent amendments?
d. How many countries have not signed the Montreal Protocol?