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

2. Chaining Up Chattanooga
1957 3rd Worst Particulate Pollution in the Country
Open Burning by permit only, odor and dust regulations, outlawed visible automobile and exhaust, limited visible industrial exhaust, monitoring programs.
In 3 years were in compliance with the Clean Air Act
Ozone Pollution still Remained.
Must meet new level of ppm

3. 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.

4. Major Air Pollutants * Six ID by the Clean Air Act (1970)
*Sulfur Dioxide – combustion of coal and oil as well as volcanic eruptions. Respiratory Irritant.
*Nitrogen Oxides – NO: colorless, odor less. NO2 : pungent, reddish gas. Combustion of fossil fuels in automobiles. Naturally produced in forest fires, lightning and bacteria. Plays major role in tropospheric ozone production.
*Carbon Oxides – CO: indentified by CAA. Colorless and odorless. Product of incomplete combustion, car exhaust, cooking with manure, charcoal and kerosene.
CO2: not identified by CAA yet. Colorless and odorless. Product of complete combustion of biomass and fossil fuels.
Incomplete vs. Complete Combustion -

5. Major Air Pollutants * Six ID by the Clean Air Act (1970)
*Particulate Matter (PM) – products of the combustion of wood, manure, biofuels, coal, oil and gasoline. Diesel fuel produces more PM than others. PM can also be rock and dust. PM10? PM2.5?
Volatiles Organic Compounds (VOC) – evaporation of fuels, paints, perfume, solvents and incomplete combustion. Role in ozone formation.
*Ozone – O3 : Produced as a secondary pollutant by NOx, VOCs and sunlight. Affect respiratory system, plants, rubber and plastic.
*Lead – from pass use of “leaded gasoline” and led based paints. Impairs central nervous system (CNS), learning and concentration.
Mercury – Primary from coal, but also oil. Impairs central nervous system. Bioaccumulation or biomagnification.

8. Smog Smog – PM and oxides. Three Types of Smog:
Photochemical smog – brown smog (ozone other oxides)
Sulfurous smog – grey smog (sulfur, sulfur dioxide)
Atmospheric brown cloud – “new term” for PM and ozone combination. Produced by combustion of fossil fuels. Contains carbon PM and NO2.

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

10. Secondary Pollutants
Secondary pollutants- pollutants that have undergone transformation in the presence of sunlight, water, oxygen, or other compounds.
Examples: ozone, sulfate and nitrate
When trying to control secondary pollutants it is important to consider the primary polluants.

11. Natural Sources of Air Pollution
Volcanoes – SO2, PM, CO, NOx
Lightning – NO, N
Forest fires –PM, NOx, CO
Plants- VOCs

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

15. Smog Formation NOx + few VOCs = O3; later O3 dissociates.
NOx + VOCs = O3 cannot dissociates.

16. Photochemical Smog

17. 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.

19. Acid Deposition

20. 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.
These secondary pollutants further break down into nitrate and sulfate which cause the acid in acid deposition.

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

22. Ways to Prevent Air Pollution
Removing sulfur dioxide from coal by fluidized bed combustion (calcium carbonate -> Calcium sulfate)
Catalytic converters on cars –remove NO and CO. Doesn’t work in the presence of lead.
Scrubbers on smoke stacks – PM, SO2.
Baghouse filters – PM, removes almost 100%.
Electrostatic precipitators – PM, use negative and positive electrodes to attract matter. Relatively clean air is produced.

26. Innovative Pollution Control
Reduce gas spilling.
Reduce wood burning stoves
Even and odd driving days.
Improve public transportation
Selling sulfur allowances.

27. 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.

28. 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

29. 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.

30. 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.

31. 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.

32. 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.

33. Reduce Ozone Depletion
1987, Montreal Protocol:
Addressed 96 ozone depleting compounds.
50% CFC Production by 2000.
Cl has leveled off at 5 ppb

34. Indoor Air Pollutants
Wood, animal manure or coal used for cooking and heating in developing countries.
Asbestos – long thin fibrous material (silicate) found insulation. No longer used.
Carbon Monoxide – from natural gas heaters
Radon – seeps through cracks in a houses foundation. Leads to lung cancer. Second leading cause of lung cancer.
VOCs in home products – glues, paints, perfumes, deodorizers, plastics.
Sick Building Syndrome – new materials releasing VOCs. Head aches, nausea, throat and eye irritation.

35. Indoor Air Pollutants
Developing vs. Developed