Air

The air, or the atmosphere, is a thin layer of gases that surrounds the earth. To scale, if the earth were the size of an apple, the atmosphere has about the same proportionate thickness as the apple peel. Within that thin layer of gases there are many important processes occurring.

What is in the air?

The air is composed primarily of two familiar gases. nitrogen (78%) and oxygen (21%). Carbon dioxide, a product of respiration, is present in small quantities (0.035%). Water vapor is also present, depending on relative humidity. Argon (0.9%) makes up most of the rest of the air. A host of other gases such as CO, O3, CH4, H2, He, NOx, SO2, etc are extremely variable but typically present in trace quantities (measured in parts per million or billion).

Another component of air is referred to as air particulate. This is in the form of very fine solids that are suspended in the air and kept suspended by the air currents. These particles are inhaled deep into the lung where they can cause health problems. Acids produced by the interaction of NOx and SO2 with very small water droplets can also be a health risk, as well as damage plants and dissolve acid soluble structures.

What is mankind putting into the air?

I think that the best place to start thinking about air pollution is with the encyclopedia Encarta. Carefully read this link from Encarta. Air Pollution

Note that global warming and ozone depletion will be covered in separate units.

More on the Major Issues

Acid rain - Read all the Frequently asked questions (FAQs)

smog - From the Encarta Encyclopedia

VOCs - Definition of volatile organic compounds

Air Particulate - Read the introduction and learn the definitions of opacity and criteria pollutant.

Tropospheric ozone - Read about Tropospheric ozone from How Stuff Works.

Take a look at the atmospheric pollution simulator at http://www.smogcity.com/welcome.htm. (Select Run Smog City from the menu.)

The Plain English Guide to the Clean Air Act - This is a really good website that explains the workings of the CAA and gives other important information.

Questions - Answer the questions in a normal (not bold) font.
Tip: When editing, holding down the shift key and pressing enter will keep from renumbering the questions.

  1. Where does most air pollution come from?
  2. What is smog?
  3. What are VOC's and where do they originate?
  4. What are three natural sources of air pollution?
  5. What is the weather phenomenon called where a layer of cooler air is trapped near the ground by a layer of warmer air above, and normal air mixing almost ceases trapping pollutants in the lower air?
  6. In the presence of atmospheric moisture, sulfur dioxide and oxides of nitrogen turn into droplets of ____________________.
  7. Name three common indoor air pollutants.
  8. In the United States, the serious effort against local and regional air pollution began with the _____________.
  9. Name two end of pipe air pollution devices.
  10. What was the Montreal protocol about?
  11. What was the Kyoto protocol about?
  12. What is opacity?
  13. What does it mean to be a criteria pollutant?
  14. How is ozone formed in the troposphere?
  15. Find a website that posts real-time Air Quality Index values. What is the URL?
  16. The EPA's Office of Air Quality Planning and Standards website contains a list of common air pollutants that are criteria air pollutants. What are they?
  17. In the Smog City Simulation, what were the four weather conditions that seemed to effect ground-level ozone production and how does each work? Fill out the statements:
        a. Increasing _____________ seems to   (increase or decrease)     ground-level ozone.
        b. Increasing _____________ seems to   (increase or decrease)     ground-level ozone.
        c. Increasing _____________ seems to   (increase or decrease)     ground-level ozone.
        d. Increasing _____________ seems to   (increase or decrease)     ground-level ozone.
  18. When ground-level ozone is highest it is always what part of the day?