1. Air Pollution and Stratospheric Ozone Depletion
Chapter 15

2. Air Pollution
“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”
“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
a. natural
- volcanoes
- forest fires
- plants
b. anthropogenic
- on-road vehicles (largest source of CO and NOx)
- industry
- power plants

4. Major Air Pollutants Six pollutants (criteria) – U.S. Clean Air Act
a. SO2
b. NOx
c. CO
d. PM
e. tropospheric ozone
f. lead

5. Sulfur Dioxide (SO2)
a. corrosive gas
b. combustion of fossil fuels (coal and oil)
c. respiratory irritant
d. released from volcanoes and forest fires

6. 1. colorless, odorless gas c. NO2 1. pungent, reddish-brown gas
Nitrogen Oxides
a. NOx (NO or NO2)
b. NO
1. colorless, odorless gas
c. NO2
1. pungent, reddish-brown gas
d. nitrogen (N2)
1. 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

7. 1. colorless, odorless gas 2. vehicle exhaust b. CO2
Carbon Oxides
a. CO
1. colorless, odorless gas
2. vehicle exhaust
b. CO2
2. photosynthesis/cellular respiration
3. 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

8. Particulate Matter (PM)
a. solid or liquid particles suspended in the air
b. sizes
1. ranges micrometer to 100 micrometer
2. larger than 10
- can be filtered out by nose and throat
3. PM10 – not filtered and deposited in
respiratory tract
4. PM2.5 – BIG health concern
c. scatter and absorb sunlight
Comes from the combustion of wood, manure and other biofuels like oil and coal and gasoline (diesel – black smoke)

9. Photochemical Oxidants a. sunlight acting on NOx and SO2
b. main focus – O3 (ozone)
1. most abundant in troposphere
2. respiratory inflammation
3. reacts with NOx and sulfur to form smog
- photochemical
* LA type, brown
- sulfurous
* London type, gray
- atmospheric brown cloud
* seen in Asia
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. a. occurs naturally in rocks and soil b. has been added to gasoline
Lead (Pb)
a. occurs naturally in rocks and soil
b. has been added to gasoline
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. 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

13. 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)

14. Photochemical Smog Smog a. originally – smoke, fog, and sometimes SO2
due to burning of coal
b. today – brown smog still a problem
c. typically urban areas, but some rural (trees and
shrubs, forest fires)
d. atmospheric conditions (higher temperatures)
1. emission of VOCs
2. NOx emissions from electric utilities
VOCs – come from vegetation as well as gasoline especially when the temperature increases
Nox – when it’s really hot outside and needing to run air conditioner
* Ozone formation and photochemical oxidants occur more rapidly at higher temperatures leading to more smog formation at higher temperatures

15. c. no VOCs or photochemical oxidants 1
c. no VOCs or photochemical oxidants 1. ozone (O3) forms during the day and breaks down at night 2. little to no photochemical smog d. VOCs present 1. VOCs combines with NOx 2. NOx no longer available to recombine with O3 in atmosphere, therefore the O3 accumulates over time
Little to no VOCs
When sunlight is present – ozone forms with lots of Nox in the atmosphere
At night – Nox is still present and will recombine with the ozone in the atmosphere to create O2 and NO2
The cycle of ozone formation is on a daily basis resulting in little smog
Smog
* Typically an urban problem but can be a problem

16. e. Thermal inversion 1. warm layer of air at mid-altitude covers a layer of cold, dense air below 2. warm inversion layer - traps emissions causing severe pollution - vehicle exhaust and industrial emissions
Reasons for inversions
when the air near the ground rapidly loses its heat on a clear night. In this situation, the ground becomes cooled quickly while the air above it retains the heat the ground was holding during the day.
Topography can also play a role in creating a temperature inversion since it can sometimes cause cold air to flow from mountain peaks down into valleys. This cold air then pushes under the warmer air rising from the valley, creating the inversion.

17. 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

18. 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)

19. 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

20. 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

21. Anthropogenic Contributions to Ozone Destruction a. 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

22. 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

23. Effort to reduce ozone depletion
a. Montreal Protocol on Substances that
Deplete the Ozone Layer
- reduce CFC production 50% by 2000

24. Indoor Air Pollution
Causes more deaths each year than outdoor air pollution
Developing v. developed
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

25. a. insulating properties b. respiratory diseases (lung cancer)
Asbestos
a. insulating properties
b. 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

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

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

28. VOCs in home products
a. strong aroma
b. glues, paints, formaldehyde
c. burning sensation of eyes, throat

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