1. Air Pollution and Stratospheric Ozone Depletion
Chapter 15

2. 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
All encompassing definition. Not just what comes out of the exhaust pipe. Before going to the next slide ask if any student has memorized or knows the layers of the atmosphere

3. Layers of the Atmosphere
General term of air pollution refers to Tropospheric pollution
Pollution in the troposphere is also called ground-level pollution
Air pollution can happen at different layers of the atmosphere. Today we are focusing on pollution that occurs in the troposphere. This is most definitely my favorite slide because the Earth is really cute, happy, and smiling. But air pollution makes the Earth really sad.

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

5. Major Air Pollutants Sulfur Dioxide Nitrogen Oxides Carbon Oxides
Particulate Matter
Volatiles Organic Compounds
Ozone
Lead
Mercury

6. Sulfur Dioxide SO2 Corrosive gas
Primarily comes from combustion of fuels like coal and oil
Respiratory irritant
Adversely effects plant tissues
Natural occurrence
Corrosive gas = can destroy solid materials
Primarily comes from combustion of coal and oil
Cause issues with breathing for both humans and animals. Makes asthma a lot worse.
When it comes to issues with plants it actually cause tissue forming issues. Each plant is effected differently, but visible symptoms are tan, reddish brown, or dark brown areas on the plant. Younger plants are more effected.
Naturally occurs from volcanic eruptions and sometimes forest fires
SO2 gas ends up converting into sulfuric acid and this can be really harmful to aquatic life and vegetation.

7. What were the ways that sulfur dioxide naturally occurs
What were the ways that sulfur dioxide naturally occurs? Do the areas with high emissions have more volcanoes? Why do I ask?
Before next slide: What is the most abundant gas in our atmosphere?

8. Nitrogen Oxides Two Forms: NO and NO2 NO Colorless Odorless NO2
Pungent
Reddish-brown
While nitrogen is the most abundant gas in our atmosphere the presence of nitrogen oxides presents major problems
There are two types of nitrogen oxides in the atmosphere that are of concern; NO nitrogen oxide and NO2 nitrogen dioxide
All combustion leads to some for of nitrogen oxide
Anthropogenic cause are: motor vehicles and fossil fuel combustion
Natural causes: lighting and forest fires
Both are considered a respiratory irritant that increases the changes of humans and animals getting infections.

9. Carbon Oxides Carbon Monoxide (CO) Colorless Odorless
Formed during incomplete combustion
Natural gas heaters malfunction
Poor ventilation
Carbon Dioxide (CO2)
Colorless
Odorless
Formed during complete combustion
Absorbed in photosynthesis
There are two types of Carbon Oxides that pollute our air. The first is Carbon Monoxide and then we also have Carbon Dioxide
Carbon monoxide is a colorless and odorless gas that is created during incomplete combustion of most matter.
When trapped in an area it can be very dangerous. Third world countries often have problems with Carbon Monoxide if their natural gas heaters malfunction or if there is poor ventilation when cooking with charcoal or kerosene.
Carbon Dioxide is also a colorless and odorless gas but it is formed during the complete combustion of most matter. Which do you think is better? CO, formed from incomplete combustion, or CO2, formed from complete combustion. And, as I have hoped you have already learned, carbon dioxide is absorbed during photosynthesis.

10. If all of these pollutants are naturally occurring,
What is the problem?
Most of the pollutants I have mentioned are naturally occurring in some way or another. So why do you think they cause problems? Why do you think I am talking to you about them?

11. Particulate Matter Also called particulates or particles
Solid or liquid particles suspended in air
Particles can be from
Wood fires
Road dust
Vehicle exhaust
Volcanoes
Fossil-fuel burning power plant smoke
Part of your lab is going to be testing for particulate matter.
When we think of the atmosphere or the air we think of gases right.
Whether you would like to call it particulate matter, particulates, or particles we are all talking about physical things suspended in the air and these can be solid or liquid.
Particulates can form from..

12. Particulate Size Size of the particles do range
Measured in micrometers
micrometer = 1 meter
Micrometer (µm)\
Average particulates 0.01 µm to 100 µm
10,000 µm
50 µm

13. Effects of Particulate Matter
Particulates can be deposited in the respiratory tract
Absorb sunlight and can affect photosynthesis
Can cause haze
Reduction in visibility

14. Lead and Mercury Lead (Pb) Occurs naturally in rocks and soils
Added to gasoline
Compounds were released into the air
Lead based paint
Mercury (Hg)
Found in coal and oil
Toxic to central nervous system
Released into the air by combustion of fossil fuels
Concentrates in the air and also water

15. Volatile Organic Compounds (VOC)
Organic compounds that become vapors at typical atmospheric temperatures
Most contain hydrocarbons (carbon-hydrogen bond)
Gasoline, lighter fluid, dry-cleaning fluid, oil based paints, perfumes, etc.
Strong aroma
Can lead to photochemical oxidants

16. Primary and Secondary Pollutants Two types:
Based on the picture and the different types what do you think the difference is between a primary pollutant and a secondary pollutant

17. Primary Pollutants
Polluting compounds that come directly out of a smoke stack, exhaust pipe, or natural emission source
These include: CO, CO2, SO2, NOX
Many VOCs are also primary pollutants
Example: gasoline is volatized from liquid to vapor, some of which leaves the car without being combusted
NOX describes both NO and NO2, scientists are lazy.

18. Secondary Pollutants
Primary pollutants that have undergone a transformation from
Sunlight
Water
Oxygen
Creates the main components for acid decomposition
We are going over acid decomposition later so do not be concerned that you do not know that but make the connection between secondary pollutants and acid decomposition

19. Anthropogenic Emissions
Highest producers for the following emissions
Carbon monoxide = On-road vehicles
Nitrogen oxides = On-road vehicles
Sulfur dioxide = Electricity generation
Particulate matter = Road dust

21. Clean Air Act Provides standards for human health and welfare
Human health: health of the human population including elderly, children, and sensitive populations (asthma)
Welfare: visibility, status of crops, natural vegetation, animals, ecosystems, and buildings

22. National Ambient Air Quality Standards (NAAQS)
Periodically sets concentration limits for each pollutant
Each pollutant as a concentration level set that should not be exceeded within a certain period of time
Particulate matter often exceeds NAAQS standards
Lead has decreased significantly

23. Clean Air Act Amendments of 1990
Regulations enacted by the U.S. Congress that address
Acid rain
Toxic emissions
Ozone depletion
Automobile exhaust
Buying and selling of sulfur dioxide emissions
Nitrogen dioxides- reduced by 10 million tons
Toxins- especially those causing cancer

24. Air Quality Index Used to describe air pollution on a given day
Determined from measurements of the concentration of five major pollutants:
Particulate matter, sulfur dioxide, carbon monoxide, ozone, and nitrogen dioxide.

25. Air Quality Index AQI = 100 AQI greater than 200 AQI exceeds 300
Air is unhealthy
AQI greater than 200
Air pollution alert is issued
AQI exceeds 300
Air pollution warning is issued - hazardous to all people.
AQI exceeds 400
Air pollution emergency is declared, and people are requested to remain indoors and minimize physical exertion

27. Black Triangle
Located in the large area of Germany, Poland, and Czech Republic
Burn high-sulfur-content coal
Emissions from power plants cause this area to be one of the most polluted areas of the world
Causes respiratory illness and forest ecosystems damage
Have words come up later. Where do you think the Black Triangle is located? Where do you think of when you think air pollution, China?

28. Hot air???
How air does what? RISES

29. Temperature??

30. Thermal Inversion
Relatively warm layer of air covers a layer of cold dense air below
Inversion layer traps emissions and they accumulate beneath
1998 in Northern China the city had already turned on their central heating system but an inversion happened trapping cold air and making the city an unbearable temperature. Many houses started to use individual coal burnings stoves for heat. The inversion layer trapped the carbon monoxide and particulates from the burning coal and caused 1000 people to suffer from carbon monoxide poisoning or respiratory ailments.

31. Occurs primarily in summer and fall
Occurs when cloud cover associated with stagnant air

33. How do we control pollution?

34. Controlling Sulfur and Nitrogen Oxide Emissions
Fluidized bed combustion
Granulated coal is burned closely to calcium carbonate
Heated calcium carbonate absorbs Sulfur Dioxide
Produces calcium sulfate
Calcium sulfate is used in the production of sheetrock
Burn temperature of fuel that are high and have the presence of oxygen allow more NOX to form
Work towards lowering the two
Catalytic converter in cars reduces NOX emissions
Catalytic converters could not be exposed to lead and increased the push to take lead out of gasoline

35. Controlling Particulate Matter
Most common means of pollution control
Easiest method is gravitational settling
Relies on gravity to remove particulates as air travels up a smokestack
Results in ash deposits that have to be properly disposed of
Sulfur can also be removed in the process

37. Baghouse Filter Dirty air enters
Dust particles are trapped in a series of filter bags
Cleaner, filtered air exits
Shaker mechanism activated periodically to remove particles from filters which can be collected at the bottom

38. Electrostatic Precipitator
Dirty air enters
Air passes negatively charged plates to give them a negative charge
Negatively charged particles are attracted to positively charged collection plates
Cleaner air exits
Collection plates are periodically discharged and particles fall for collection

39. Scrubber Dirty air enters
Combustion exhaust streams move upward through shower of mist water
Mist collects particles and pushed them to bottom
Dirty water moves to sludge removal system
Sludge is separated from water
Water is reused
Clean air exits through screen

40. Indoor Pollution
What is it?

41. Developing Countries
People use wood, animal manure, and coal for heating and cooking
Biomass and coal are usually burnt in open-pit fires that do not have the proper fuel and air mix for complete combustion
Normally no ventilation or exhaust system
1.6 million deaths from indoor air pollution
World Health Organization reports 1.6 million deaths from indoor air pollution, 56% of those are children under the age of 5 and 90% of those death come from developing nations.

43. Developed Countries People are spending more time indoors
Working conditions
Homes are more tightly insulated
Materials in the home that are made from plastic and other petroleum-based compounds

44. Asbestos
Long, thin, fibrous silicate mineral with insulating properties
Cause respiratory disease like asbestosis and lung cancer
Not dangerous until it is disturbed

45. Carbon Monoxide Much more dangerous as an indoor pollutant
Occurs when there is a malfunction of natural gas heaters
Colorless and odorless allowing it to build up quickly
Causes interference with the oxygenation of the blood
Extended exposure causes death

46. Radon Radioactive gas that occurs naturally from decay of uranium
Seems into home through cracks in foundation
Can be transported through groundwater
Attaches to dust particles in the air
21,000 die from radon induced lung disease

47. VOCs in Home Products
Used in building materials, furniture, glues, and paints
Deodorizers and solvents can contain VOCs and should not be inhaled
Plastic fabrics, construction materials, and carpets can release VOCs over time

49. Sick Building Syndrome
Inadequate or faulty ventilation
Chemical contamination from indoor sources like glues, carpeting, furniture, cleaning agents, and copy machines
Chemical contamination from outdoor sources like vehicle exhaust transferred insides
Biological contamination from indoors or outdoors like mold or pollen

50. Acid Deposition NOX and SO2 are released in the air
Come in contact with atmospheric oxygen and water
Through series of reaction, they are transformed into Sulfuric acid (H2SO4) and Nitric acid (HNO3)
These breakdown further to produce sulfate and nitrate and hydrogen ions (H+)
H+ is what generates the acidity in acid deposition

51. 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

53. 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.
Ozone layer in the stratosphere called the ozone shield
Absorbs most of the potentially hazardous ultraviolet radiation from the sun
Ultraviolet radiation consists of wavelengths between 0.1 and 0.4 μm
Ultraviolet A (UVA)
Ultraviolet B (UVB)
Ultraviolet C (UVC).

54. Ultraviolet Radiation and Ozone
Ultraviolet C (UVC)
Shortest wavelength and most energetic of the types of ultraviolet radiation
Sufficient energy to break apart diatomic oxygen (O2)
Each of these oxygen atoms may combine with an O2 molecule to create ozone
UVC strongly absorbed in the stratosphere, and negligible amounts reach the Earth’s surface

55. Ultraviolet Radiation and Ozone
Ultraviolet A (UVA)
Longest wavelength
Least energy of the three types of ultraviolet radiation
UVA can cause some damage to living cells
Not affected by stratospheric ozone, and is transmitted to the Earth’s surface

56. Ultraviolet Radiation and Ozone
Ultraviolet B (UVB)
Energetic and strongly absorbed by stratospheric ozone
Ozone is the only known gas that absorbs UVB
Depletion of ozone in the stratosphere results in an increase in the UVB that reaches the surface of the Earth

57. Ultraviolet Radiation and Ozone
Approximately 99% of all ultraviolet solar radiation (all UVC and most UVB) is absorbed by the ozone layer
Natural service function
Protects us from the potentially harmful effects of ultraviolet radiation

58. Measurement of Stratospheric Ozone
First measured in 1920s using Dobson ultraviolet spectrometer.
Dobson unit (DU) - 1DU = 1 ppb O3
Now have measurements from all over the world for 30 years
Ground based measurements first identified ozone depletion over the Antarctic
Concentrations have been decreasing since the mid-1970s
“Ozone hole”

59. 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

60. 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.

61. 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.

62. 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.

64. 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.

65. Future of Ozone Depletion
The Montreal Protocol
Outlined a plan for the eventual reduction of global emissions of CFCs to 50% of 1986 emissions
Elimination of the production of CFCs by 1999
Assessment of the protocol suggest that CFCs will return to pre-1980 levels by 2050