1. Human Impact on Air Resources
Chapter 26.3

2. Global Impacts of Air Pollution
Global Warming
- Greenhouse Effect - a natural process in which atmospheric gases trap thermal energy.
- over time, the Earth’s climate has undergone both warming and cooling trends.
- the main greenhouse gas carbon dioxide, however, has been increasing due to the increased use of fossil fuels.
- Scientists believe this rise in CO2 has caused the avg. surface temperature of the Earth to rise 0.5oC over the past century.
Video – Greenhouse Effect (2:15 min)

3. Question!
What is the main greenhouse gas?

4. B. Photochemical Smog
- a yellow-brown haze that forms around heavily populated areas.
- created by the reaction of car exhaust and oxygen in the atmosphere.
- produces ozone (O3) which is harmful to breathe.
Video – Future Car (5:01 min)

5. Question!
What is the main cause of smog?

6. C. Ozone Depletion
- ozone (O3) in the upper atmosphere protects the Earth from harmful UV light from the Sun.
- chemicals called CFC’s were used in the 1960’s ’s as a refrigerant in air conditioners, refrigerators, and freezers.
- Scientists discovered that these chemicals were damaging the ozone layer and they are now banned from use in most of the world.
- the ozone “hole” should eventually be repaired in a few hundred years as the CFC’s drift into space.
Video – Ozone Hole (5:04 min)

7. Question!
What chemical kills the ozone layer?

8. D. Acid Precipitation
- burning fossil fuels that contain sulfur releases toxic sulfur dioxide and nitric oxide into the air.
- these combine with moisture in the air to produce sulfuric and nitric acids.
- these acids harm aquatic life, plant life, dissolve nutrients from the soil, and increase weathering of buildings and monuments.
- most acid rain in the US is from the burning of coal in electrical power plants.

9. Question!
What kind of acid is found in acid rain?

10. E. Reducing Air Pollution
- Government regulations have been very effective in reducing emission of air pollutants.
- These include:
- emission standards for coal burning power plants and new cars.
- banning the use of CFC’s.
- encouraging the use of alternative energy sources.