1. Air Pollution and Stratospheric Ozone Depletion
Chapter 15
Air Pollution and Stratospheric Ozone Depletion

2. Chattanooga
Tennessee. Along a natural basin of the Appalachian mountains.
After civil war, became a leading manufacturing center in the nation.
1957-3rd worst particulate pollution in the nation.
1969 (year before CAA)-created its own air pollution legislation (Air pollution Control Ordinance). City and County also put new pollution monitoring techniques. $40 million in cleanup efforts.

3. 1972- Chattanooga meets compliance with the CAA quality standards.
To maintain their clean air:
Comprehensive recycling program.
Largest municipal fleet of electric buses in the US.
Despite efforts, Ozone concentrations exceeded the standard.
Chattanooga made the efforts again to comply through combined government, public, and local industry efforts.

4. Air Pollution
Air pollution- the introduction of chemicals, particulate matter, or microorganisms into the atmosphere at concentrations high enough to harm plants, animals, and materials such as buildings, or to alter ecosystems.
Sources can be natural such as volcanoes and fires or anthropogenic like automobiles and factories.
Air pollution doesn’t stay local: Acid rain rainfall on the west coast of the US has been caused by pollution in Asia.

5. Major Air Pollutants
CAA 1970 identified 6 pollutants that significantly threaten human well-being. Criteria air pollutants.
Sulfur Dioxide
Nitrogen Oxides
Carbon monoxide (dioxide listed in US supreme court rule)
Particulate Matter
Ozone
Lead
Other air pollutants
Mercury
Volatiles Organic Compounds

8. Primary Pollutants
Primary pollutants- polluting compounds that come directly out of the smoke-stack, exhaust pip, or natural emission source.
Examples: CO, CO2, SO2, NOx, and most suspended particulate matter.

9. Secondary Pollutants
Secondary pollutants- pollutants that have undergone transformation in the presence of sunlight, water, oxygen, or other compounds.
Examples: ozone, sulfate and nitrate

11. Natural Sources of Air Pollution
Volcanoes
Lightning
Forest fires
Plants

12. Anthropogenic Sources of Air Pollution
On-road vehicles
Power plants
Industrial processes
Waste disposal

13. Deposit within the respiratory system and are usually more toxic.

14. Los Angeles Type: Brown Smog
Photochemical Smog
Los Angeles Type: Brown Smog
London type: Gray Smog

15. Temperature Atmospheric temperature affects the formation of smog.
Evaporation of VOC’s increase as the temperature increases.
NOx emissions from electric utilities also increase as air- conditioning demands increase.
Chemical reactions that form ozone proceed more rapidly at higher temperatures
These factors combine to form even higher smog concentrations…positive feedback loop.

16. Thermal Inversions
Thermal Inversion- when a relatively warm layer of air at mid-altitude covers a layer of cold, dense air below.
The warm inversion layer traps emissions that then accumulate beneath it.

17. Acid Deposition
All rain is slightly acidic. pH’s less than 5.6 are considered acid deposition. Pollutants combine with water & oxygen in atmosphere with primary pollutants to form sulfuric acid and nitric acid.

18. Acid Deposition
Acid deposition- occurs when nitrogen oxides and sulfur oxides are released into the atmosphere and combine with atmospheric oxygen and water. These form the secondary pollutants nitric acid and sulfuric acid.
Acid deposition increased substantially in the US from the 1940’s-1990’s due to human activity.
These secondary pollutants further break down into nitrate and sulfate which cause the acid in acid deposition.

19. Effects of Acid Deposition
Direct effects
Indirect effects
Lowering the pH of lake water
Damaging statues, monuments, and buildings
Mobilizing metals that are found in soils and releasing these into surface waters
Decreasing species diversity of aquatic organisms

20. Ways to Prevent Air Pollution
Removing sulfur dioxide from coal by fluidized bed combustion. (using less fuel: Better)
Catalytic converters on cars
Scrubbers on smoke stacks
Baghouse filters
Electrostatic precipitators

21. Bag house filter

22. Electrostatic precipitator

23. Scrubber

24. Stratospheric Ozone
The stratospheric ozone layer exists roughly kilometers above the Earth.
Ozone has the ability to absorb ultraviolet radiation and protect life on Earth.

25. Formation and Breakdown of Ozone
First, UV-C radiation breaks the bonds holding together the oxygen molecule )2, leaving two free oxygen atoms: O2 + UV-C -> 2O
Sometimes the free oxygen atoms result in ozone: O2 + O -> O3
Ozone is broken down into O2 and free oxygen atoms when it absorbs both UV-C and UV-B ultraviolet light: O3 + UV-B or UV-C -> O2 + O

26. Anthropogenic Contributions to Ozone Destruction
Certain chemicals can break down ozone, particularly chlorine.
The major source of chlorine in the stratosphere is a compound known as chlorofluorocarbons (CFCs)
CFCs are used in refrigeration and air conditioning, as propellants in aerosol cans and as “blowing agents” to inject air into foam products like Styrofoam.

27. Anthropogenic Contributions to Ozone Destruction
When CFCs are released into the troposphere they make their way to the stratosphere.
The ultraviolet radiation present has enough energy to break the bond connecting chlorine to the CFC molecule.
which can then break apart the ozone molecules.

28. Anthropogenic Contributions to Ozone Destruction
First, chlorine breaks ozone’s bonds and pulls off one atom of oxygen, forming a chlorine monoxide molecule and O2: O3 + Cl -> ClO + O2
Next, a free oxygen atoms pulls the oxygen atom from ClO, liberating the chlorine and creating one oxygen molecule: ClO + O -> Cl + O2
One chlorine atom can catalyze the breakdown of as many as 100,000 ozone molecules before it leaves the stratosphere.

29. Depletion of the Ozone Layer
Global Ozone concentrations had decreased by more than 10%.
Depletion was greatest at the poles
Decreased stratospheric ozone has increased the amount of UV-B radiation that reaches the surface of Earth.

30. Indoor Air Pollutants Causes more deaths per year than outdoor.
1.6 million deaths worldwide: 56% in ages of 5 or less.
Developing countries
Developed countries
Wood, animal manure or coal used for cooking and heating in developing countries.
CO and PM’s
Acute respiratory infections, pneumonia, bronchitis, cancer.
More time in doors, better insulation, building materials made from petroleum and plastics that give off vapors.
Asbestos
Carbon Monoxide
Radon
VOCs in home products

31. 80-90% of our time is spent indoors.