1. AIR POLLUTION & STRATOSPHERIC OZONE DEPLETION
CHAPTER 18
AIR POLLUTION & STRATOSPHERIC
OZONE DEPLETION

2. Air Pollution
DEFINED: Introduction of chemicals, particulate matter (PM), or microorganisms into the atmosphere at concentrations high enough to harm plants, animals, and materials such as buildings or alter ecosystems
ALSO CALLED: “pollution of troposphere” or “ground-level pollution”
It can occur naturally from things like volcanoes and fires or it can be anthropogenic
In recent years, countries in Asia have had the worst outdoor air pollution; Asia, Africa and SA have health issues mainly due to indoor air pollution
Air pollution can happen over long distances

3. SOURCES - volcanoes - forest fires - plants b. anthropogenic
a. natural
- volcanoes
- forest fires
- plants
b. anthropogenic
- on-road vehicles
(largest source of CO
and NOx)
- industry
- power plants

4. THE CLEAN AIR ACT Enacted in 1970 Amended in 1977
Amended again in 1990

5. Major Air Pollutants
Six pollutants – U.S. Clean Air Act

6. Sulfur Dioxide (SO2) corrosive gas
combustion of fossil fuels (coal and oil)
respiratory irritant
released from volcanoes and forest fires

7. Nitrogen Oxides NOx (NO or NO2)
NO (nitric oxide): colorless, odorless gas
NO2 (nitrogen dioxide): pungent, reddish-brown gas
Nitrogen (N2): makes up 78% of atmosphere
Anthropogenic – motor vehicles, stationary fossil fuel combustion
Natural – forest fires, lightning, bacteria in soil
* Plays an important role in forming tropospheric ozone as well as photochemical smog

8. Carbon Oxides
CO (carbon monoxide): colorless, odorless gas; vehicle exhaust
CO2 (carbon dioxide): colorless, odorless gas; cellular respiration; burning of fossil fuels
CO – incomplete combustion of most matter; significant in urbanized areas
- dangerous indoor air pollutant if it is poorly ventilated (exhaust systems on heaters are not working properly)
CO2 – complete combustion of matter and biomass

9. Particulate Matter (PM)
Solid or liquid particles suspended in the air
Sizes range from microns to 100 microns
Larger than 10 - can be filtered out by nose and throat
PM10 – not filtered and deposited in the respiratory tract
PM2.5 – BIG health concern; scatter and absorb sunlight
Comes from the combustion of wood, manure and other biofuels like oil and coal and gasoline (diesel – black smoke)

10. Photo-chemical Oxidants
Sunlight acting on NOx and SO2
Main focus is O3 (ozone):
Most abundant in troposphere Often causes respiratory inflammation
Reacts with NOx and sulfur to form smog
LA type - brown
London type - gray
Generally harmful to plant tissue, human respiratory tissue
When ozone is in the presence of nitrogen oxides and VOCs, it creates even more harmful pollutants
Smog-reduced sunlight
- created through the presence of sulfur and Nox and ozone and other photochemical oxidants reacting together to create certain particulate matter contributing to scattering light
Atmospheric brown cloud – derived from combustion of fossil fuels and burning biomass
* reduces tourism

11. Lead (Pb)/ Mercury (Hg)
a. occurs naturally in rocks and soil
b. has been added to gasoline (to reduce engine knock) and paint (to speed drying)
c. persistent
Mercury (Hg)
a. coal and oil – released into atmosphere
b. toxic to CNS
Lead – in gasoline it improves vehicle perofrmance ; lead released into air and travels with wind and deposits by rain or snow
Largest uncontrolled source of Hg – coal burning power plants

12. Primary and Secondary Pollutants
a. direct source
b. CO, CO2, SO2, NOx, most PM and VOCs
Secondary
a. product of primary pollutant undergoing a reaction
ex) ozone (O3)

13. VOCs (volatile organic compounds)
a. become vapors at typical atmospheric temperatures b. hydrocarbons c. gasoline, lighter-fluid, oil-based paints d. strong aromas e. lead to ozone formation

14. Acid Deposition Formation a. NOx and SOx released into atmosphere
(primary)  nitric acid and sulfuric acid
(secondary)  nitrate, sulfate, and hydrogen
ions (generate acidity in acid deposition
b. fall as wet or dry deposition
c. reduced in US due to Clean Air Act
Effects
a. lowers pH of water
b. detrimental to aquatic organisms
c. decrease in species diversity
d. erode statues, monuments, and buildings
e. harm tree species (Red Spruce in NE US)

15. Stratospheric Ozone Tropospheric Ozone Stratospheric Ozone
Oxidant that harms respiratory systems
Protective shield against radiation from Sun (UV-B)
Air pollutant damaging lung tissue and plants
Critically important to life
“ground-level ozone”
“global sunscreen”
UV-A reaches this layer
Absorbs UV-B and UV-C

16. Formation and Breakdown of Ozone
Occurs in closed loop cycle
a. O2 + UV-C  2O
b. O2 + O  O3
c. O3 + UV-B or UV-C  O2 + O
Ozone continuously formed/broken down in presence of sunlight
UV-C breaks the bonds holding together the oxygen leaving two free oxygen molecules (only happens to a small number of oxygen molecules, therefore most of the O2 remains unaffected in the atmosphere)
When the oxgen molecules (O2) reactions with the free oxygen molecules floating through the atmosphere, the result is ozone
- therefore in the presence of ultraviolet radiation, oxygen is converted to ozone
c. Ozone is broken down into O2 and free oxygen atoms when it absorbs with UV-C or UV-B radiation

17. Anthropogenic Contributions to Ozone Destruction
Chlorine
1. major source – CFCs
2. O3 + CL  ClO + O2
ClO + O  Cl + O2
O3 + O  2 O2
3. catalyst, does not get used up
4. ozone no longer able to absorb UV-B
CFCs
Extremely stable
Nontoxic
Nonflammable
Does not degrade once released into atmosphere
Does not dissolve in water
Does not undergo any chemical change
When CFC reaches the stratosphere and is in the presence of ultraviolet radiation, the bond between the chlorine and CFC is broken, resulting in chlorine atom in the atmosphere
Chlorine breaks down ozone and pulls off one free oxygen and forming a chlorine monoxide molecule and O2
Free oxygen pulls the oxygen atom from the chlorine monoxide and creating an oxygen molecule (O2)
Now the free chlorine is ready to break down more ozone molecules

18. Depletion of Ozone layer
a. Greatest at the poles since 1970
b. “Ozone hole” in Antarctica
1. seasonal depletion
2. cold weather
- build up of ice crystals mix with NO
- accumulation of Cl
3. sunny weather
- UV breaks down more Cl catalyzing
ozone destruction

21. Indoor Air Pollution
Causes more deaths each year than outdoor air pollution
Developing
Use wood, animal manure or coal for cooking
Poorly ventilated
Not allowed for complete combustion when burned
No exhaust system CO
Developed
* We spend more time inside

22. Asbestos insulating properties respiratory diseases (lung cancer)
c. not dangerous until disturbed
* Insulating materials become old or damaged and the fine fibers within them become airborne and get embedded into respiratory tract

23. Carbon Monoxide
a. malfunctioning exhaust system- typically natural gas b. binds with hemoglobin more efficiently than O2 c. lead to oxygen deprivation in brain

24. Radon b. exists in bedrock c. seep through crack in foundation
a. Radon-222, decay of uranium
b. exists in bedrock
c. seep through crack in foundation
d. second leading cause of lung cancer

25. VOCs in home products strong aroma glues, paints, formaldehyde
burning sensation of eyes, throat

26. Sick Building Syndrome
a. high levels of VOCs and other pollutants
b. headaches, sore throat, fatigue
c. sources
- mold, pollen
- cleaning agents