1. Primary and Secondary Pollutants; pH
AIR POLLUTION
Primary and Secondary Pollutants; pH

2. Types of Pollutants
Primary pollutants – those released directly into the lower atmosphere, i.e. CO
Secondary pollutants – those that are formed by the combination of primary pollutants in the atmosphere. For example, acid rain is produced from the combination of sulfur oxides (SO2 and SO3) and water vapor.
Other examples: HNO3, H2O2, H2SO4. PANs, NO3-, SO4-

3. AIR POLLUTION
Some primary air pollutants may react with one another or with other chemicals in the air to form secondary air pollutants.
Figure 19-3

4. How Do They Form and What Are the Sources
How are secondary pollutants formed?
Describe the sources of primary pollutants?
 Answers:
1. Primary air pollutants react with one another or with other chemicals in the atmosphere and form secondary pollutants.
2. Mobile exhaust, natural pollutants (volcanic ash, etc.), and stationary pollutants from refineries and processing plants.

5. The pH (potential of Hydrogen) is the concentration of hydrogen ions in one liter of solution.
Concentration of H+ ions. Calc: pH 7 & pH 4 = 1000 times greater
Figure 2-5

6. Formation of Acid Deposition
The sequence of events which result in acid deposition formation are
Combustion releasing SO2 and NOx
Secondary pollutants are formed
Dissociation of pollutants
Deposition of ions on vegetation or soil

7. Other Acid Rain Factoids
Normal rainfall has a pH of 5.7
Typical rainfall in eastern US has a pH of 4.6
In general, acid rain has harmful effects for terrestrial ecosystems when it falls below a pH of 5.6
Linked to NOx and SO2
Fish kills; damages or kills aquatic life
Stunts plant growth and makes them susceptible to disease
Damages statues, buildings and car finishes

8. General Terms
AQI (Air Quality Index) – measurement of air quality; usually in parts per million (ppm).
National Ambient Air Quality Standards – specify the maximum allowable level, averaged over a specific time period, for a certain pollutant.
Point source pollution describes a specific location from which pollution is released; i.e., factory or forest fire.
Non-point source pollution – pollution that does not have a specific point of release; i.e., methane from cows, automobiles.

9. Behavior in the Atmosphere
Humans have added pollutants to the air throughout history (early man’s fire, Roman’s smelting lead);[anthropogenic]. However, large-scale production of pollutants began with the Industrial Revolution.
Today, idling cars add most air pollution………”Welcome to McDonald’s; may I take your order?” 
Once air pollutants have entered the atmosphere, they may be
Removed with precipitation
Transformed through chemical reactions
Transported on air currents and wind
Trapped by topography and inversions

10. Temperature Inversion
Temperature inversions trap pollutants close to the Earth’s surface and exacerbate pollution problems.
Often occur at night
Result from
Warm air on top of cooler, stagnant air
Movement of a cold front
From infiltration of ocean air by a cooler onshore breeze

11. Thermal Incline Common in Coastal areas – LA
Areas located in basins – LA & Mexico City
Valleys surrounded by mountains – Smokey Mtns.

12. Affect on Humans London (1952) – 4,000 deaths
“killer fog” resulted from burning large quantities of coal
Donora, PA (1948) – 20 deaths; 7,000 sickened
Fluoride emissions from US Steel Co.
New York City (1963) – 300 deaths; thousands of illnesses

13. Smog Industrial (gray) smog Photochemical (brown) smog
Results from incomplete combustion of fossil fuels such as coal, oil and natural gas
Releases CO, CO2, soot, sulfur and Hg
Reacts with oxygen and sunlight
Photochemical (brown) smog
Formed from reactions involving nitrogen oxides
These reactions also produce acid rain and tropospheric ozone

15. Indoor Air Pollution

16. Figure 19.11
Science: some important indoor air pollutants. QUESTION: Which of these pollutants are you exposed to? (Data from U.S. Environmental Protection Agency)
Fig , p. 453

17. Factoids
Asbestos, radon-222, formaldehyde and cigarette smoke – 4 most dangerous
Dust mites, cockroach droppings, mold & mildew – contributors to asthma

18. Radon 55% of our exposure to radiation comes from radon
Strong carcinogen
colorless, tasteless, odorless gas
formed from the decay of uranium-238
found in nearly all soils, igneous rock
levels vary geographically
Remediation includes sealing or venting areas

19. (From: http://www.epa.gov/iaq/radon/zonemap.html)
Zone pCi/L
>4
<2

20. Radon Risk: Non-Smoker
Radon Level
(pCI/L)
If 1000 people who did not smoke were exposed to this level over a lifetime.. About X would get lung cancer
This risk of cancer from radon exposure compares to …
What to do: 20 8
Being killed in a violent crime
Fix your home 10 4 3
10x risk of dying in a plane crash 2
Risk of drowning
<1
Risk of dying in a home fire
1.3
Average indoor radon level
0.4
If you are a former smoker, your risk may be higher

21. Radon Risk: Smoker If you are a former smoker, your risk may be lower
Radon Level
(pCI/L)
If 1000 people who smoke were exposed to this level over a lifetime.. About X would get lung cancer
This risk of cancer from radon exposure compares to …
What to do:
Stop smoking and … 20
135
100x risk of drowning
Fix your home 10 71
100x risk of dying in a home fire 8 57 4 29
100x risk of dying in a plane crash 2 15
2x the risk of dying in a car crash
1.3 9
Average indoor radon level
0.4 3
If you are a former smoker, your risk may be lower

22. Radon: How it Enters Buildings
Cracks in solid floors
Construction joints
Cracks in walls
Gaps in suspended floors
Gaps around service pipes
Cavities inside walls
The water supply

23. Radon: Reducing the Risks
Sealing cracks in floors and walls
Simple systems using pipes and fans for ventilation
More information: ech
Such systems are called "sub-slab depressurization," and do not require major changes to your home. These systems remove radon gas from below the concrete floor and the foundation before it can enter the home. Similar systems can also be installed in houses with crawl spaces.

24. EPA Studies Concluded
Levels of 22 common pollutants are generally higher inside US homes and commercial buildings than outdoors
Indoor pollutants may be linked to Sick Building Syndrome
Pollution levels inside cars in traffic-logged areas are higher than outside
Health risks from exposure to chemical pollutants are higher for people in developed countries because they spend more time indoors or inside vehicles

25. Sick Building Syndrome (SBS) Building Related Illness (BRI)vs
Building Related Illness (BRI)

26. Sick Building Syndrome
A building is considered “sick” when at least 20% of its occupants suffer persistent symptoms that disappear when they exit the building
Causes(s) not known or recognizable
At least 17% of the 4 million commercial buildings in the US are considered “sick”

27. Complaints/Symptoms Headaches Dry Skin Fatigue Nasal Congestion
Reduced Mentation
Irritability
Eye, nose or throat irritation
Dizziness
Dry Skin
Nasal Congestion
Difficulty Breathing
Nose Bleeds
Nausea

29. Legislation Air Pollution Control Act (1955)
Precursor to CAA
Awareness; national problem (Donora, PA; LA, London)
Clean Air Act (1963) – begins regulation of air pollution
Established Air Quality Control regions
Set air quality standards for public health
Developed motor vehicles emissions standards
Set point source (stationary) emissions standards for all new facilities
Gave a time table to power plants to cut emissions
Established a cap-and-trade program for SO2 in 1990

30. Amendments CAAA (Clean Air Act Amendments) – made law stricter 1965
1970 – unrealistic; caused economic hardship for companies, so……..
1990 – allowed companies to use “Best Available Control Technologies” – best tech they could afford; emphasis on alternative fuels
Does NOT regulate CO2 emissions (GHG)

31. Strategies to Reduce Air Pollutants
Removing sulfur from coal
Burning low-sulfur coal
Convert coal to liquid or gaseous fuel (cleaner burning)
Shifting to less polluting fuels
Use emission-control devices
Wet-scrubbers – decrease SO2 from coal-burning power plants
Electrostatic precipitators – remove particulates from smokestacks
Baghouse filters
Cyclone separators

32. Liquid Scrubber

33. Electrostatic Precipitator

34. Sulfur Dioxide Control
Advanced Flue Gas Desulfurization Demonstration Project
|Objective: To reduce SO2 emissions by 95% or more at approximately one-half the cost of conventional scrubbing technology, significantly reduce space requirements, and create no new waste streams.
Technology/Project Description: Pure Air built a single SO2 absorber for a 528-MWe power plant. Although the largest capacity absorber module of its time in the United States, space requirements were modest because no spare or backup absorber modules were required. The absorber performed three functions in a single vessel: prequenching, absorbing, and oxidation of sludge to gypsum. Additionally, the absorber was of a co-current design, in which the flue gas and scrubbing slurry move in the same direction and at a relatively high velocity compared to that in conventional scrubbers. These features all combined to yield a state-of-the-art SO2 absorber that was more compact and less expensive than contemporary conventional scrubbers.
Other technical features included the injection of pulverized limestone directly into the absorber, a device called an air rotary sparger located within the base of the absorber, and a novel wastewater evaporation system. The air rotary sparger combined the functions of agitation and air distribution into one piece of equipment to facilitate the oxidation of calcium sulfite to gypsum.
Pure Air also demonstrated a unique gypsum agglomeration process, PowerChip®, to significantly enhance handling characteristics of adsorbed flue gas desulfurization AFGD-derived gypsum.

35. Energy Policy & Conservation Act of 1975
Gave the Department of Transportation authority to set Corporate Average Fuel Economy (CAFE) standards for motor vehicles
Intended to decrease both fuel consumption and emissions
Average car = 27.5 mpg
Pickups, trucks, minivans, SUVs = 22.7 mpg
Catalytic converters – oxidize most VOCs to CO2 and water; and most CO to CO2
New cars built after 2000 emit 75% less pollution than cars built before 1970

36. Milestones in the Control of Automotive Emissions
Autos linked to air pollution
Original CAA, PCV valves
HC & CO exhaust controls
CAA amendments, EPA formed
Evaporative controls
First I/M Program
NOx exhaust controls
First catalytic converters
New cars meet statutory limits
Volatility limits on gasoline
New CAA Amendments

37. Source: NATIONAL AIR POLLUTANT EMISSION TRENDS,
United States Environmental Protection Agency Office of Air Quality Planning and Standards EPA-454/R
March 2000

38. Comparison of 1970 and 1999 Emissions
Source: Latest Findings on National Air Quality: 1999 Status and Trends EPA EPA-454/F
Since the 1970 Clean Air Act was signed into law, emissions of each of the six
pollutants decreased, with the exception of NOx . Between 1970 and 1999,
emissions of NOx increased 17 percent. The majority of this increase can be
attributed to heavy-duty diesel vehicles and coal-fired power plants. EPA has
major initiatives to reduce emissions of NOx considerably from these sources.
Emissions of NOx contribute to the formation of ground-level ozone (smog),
acid rain, and other environmental problems, even after being carried by the
wind hundreds of miles from their original source.

39. Reduction in Air Pollution
EPA report (2005) – reduction between 1970 & 2004
Lead
Suspended particulate matter CO
SO2

40. Question
What are some reasons why a multinational company would choose to build a manufacturing facility in India or China rather than in the US or Europe?

41. China High levels of air pollution – burn lots of coal
No/few regulations
No scrubbers
Shut down industry just before and during 2008 Olympics

42. Other Primary Pollutants
CFCs (chlorofluorocarbons)
Invented in the 1930s
Used as coolants, propellants, in fire extinguishers, and aerosols
Known to cause depletion of stratospheric ozone
Ozone depletion can lead to
Eye cataracts
Skin cancer
Weakened immune systems
Decrease in productivity of marine and terrestrial ecosystems
PCBs (polychlorinated biphenyls)
A group of 209 toxic, oily, synthetic chlorinated hydrocarbon compounds that can be biologically amplified in food chains/webs
Neurotoxin
Sources: pesticides, hydraulic fluids, transformers, wood treatments, paint, plastic, roofing materials, lubricants………………..

43. Stratospheric Ozone
It is formed from the reaction of O with O2 in the presence of ultraviolet light
Without interference, there is a steady state of ozone being created and destroyed
The ozone absorbs UV-B rays and decomposes into O2 and O
It is a closed loop cycle

44. How Have We Depleted O3 in the Stratosphere and What Can We Do?
Widespread use of certain chemicals has reduced ozone levels in the stratosphere, which allows for more harmful ultraviolet radiation( UV-A and UV-B) to reach the earth’s surface.
To reverse ozone depletion, we must stop producing ozone-depleting chemicals and adhere to the international treaties that ban such chemicals.

45. Our Use of Certain Chemicals Threatens the Ozone Layer
Ozone Thinning
Seasonal depletion in the stratosphere
Antarctica and Arctic
not in tropics
1930: Midgely
Discovered the first CFC
1984: Rowland and Molina
CFCs (freons) were depleting O3
Others – halons, hydrobromofluorocarbons (HBFC’s), methyl bromide, hydrogen chloride, carbon tetrachloride, methyl chloroform

46. Rowland and Molina (1974)…….
Research
CFCs are persistent in the atmosphere
Rise into the stratosphere over years
Break down under high-energy UV radiation
Halogens produced accelerate the breakdown of O3 to O2
Each CFC molecule can last years
1988: DuPont stopped producing CFCs – stalled for 15 years(1974)
1995: Nobel Prize in chemistry

47. Summary of Reactions CFCl3 + UV → Cl + CFCl2
Sun
Ultraviolet light hits a chlorofluorocarbon (CFC) molecule, such as CFCl3, breaking off a chlorine atom and leaving CFCl2.
Summary of Reactions CFCl3 + UV → Cl + CFCl2
Cl + O3 → ClO + O2
Repeated many times
UV radiation
ClO + O → Cl + O2 Cl C Cl Cl F C Cl Cl F Cl
Once free, the chlorine atom is off to attack another ozone molecule and begin the cycle again. Cl O O O O
Ozone O
The chlorine atom attacks an ozone (O3) molecule,
pulling an oxygen atom off it and leaving an oxygen molecule (O2).
Figure 19.D
Simplified summary of how chlorofluorocarbons (CFCs) and other chlorine-containing compounds can destroy ozone in the stratosphere faster than it is formed. Note that chlorine atoms are continuously regenerated as they react with ozone. Thus, they act as catalysts—chemicals that speed up chemical reactions without being used up by the reactions. Bromine atoms released from bromine-containing compounds that reach the stratosphere also destroy ozone by a similar mechanism. O
A free oxygen atom pulls the oxygen atom off the chlorine monoxide molecule to form O2. O O O O Cl O O O O Cl
The chlorine atom and the oxygen atom join to form a chlorine monoxide molecule (ClO). O O
Fig. 19-D, p. 525

48. Why Should We Worry about Ozone Depletion
Damaging UV-A and UV-B radiation
Increase eye cataracts and skin cancer
Impair or destroy phytoplankton- Antarctic
base of food web
Loss of removal of carbon dioxide from the atmosphere – worsening global warming

49. Effects of ozone depletion
Figure 19.20
Science: expected effects of decreased levels of ozone in the stratosphere (Concept 19-4A). Question: Which three of these effects do you think are the most threatening? Why?
Stepped Art
Fig , p. 524

50. Ultraviolet A Ultraviolet B
This long-wavelength (low-energy) form of UV radiation causes aging of the skin, tanning, and sometimes sunburn. It penetrates deeply and may contribute to skin cancer.
This shorter-wavelength (high-energy) form of UV radiation causes sunburn, premature aging, and wrinkling. It is largely responsible for basal and squamous cell carcinomas and plays a role in malignant melanoma.
Ultraviolet A
Ultraviolet B
Hair
Thin layer of dead cells
Squamous cells
Epidermis
Basal layer
Sweat gland
Melanocyte cells
Figure 19.E
Structure of the human skin and the relationships between ultraviolet (UV-A and UV-B) radiation and the three types of skin cancer. (Data and photos from the Skin Cancer Foundation)
Dermis
Blood vessels
Basal cell
Fig. 19-E (1), p. 526

51. Figure 19.E
Structure of the human skin and the relationships between ultraviolet (UV-A and UV-B) radiation and the three types of skin cancer. (Data and photos from the Skin Cancer Foundation)
Fig. 19-E (2), p. 526

52. Ultraviolet A Ultraviolet B
Thin layer of dead cells
Squamous cells
Epidermis
Basal layer
Sweat gland
Melanocyte cells
Dermis
Blood vessels
Basal cell
Hair
This long-wavelength (low-energy) form of UV radiation causes aging of the skin, tanning, and sometimes sunburn. It penetrates deeply and may contribute to skin cancer.
This shorter-wavelength (high-energy) form of UV radiation causes sunburn, premature aging, and wrinkling. It is largely responsible for basal and squamous cell carcinomas and plays a role in malignant melanoma.
Ultraviolet A
Ultraviolet B
Figure 19.E
Structure of the human skin and the relationships between ultraviolet (UV-A and UV-B) radiation and the three types of skin cancer. (Data and photos from the Skin Cancer Foundation)
Squamous Cell Carcinoma
Basal Cell Carcinoma
Melanoma
Stepped Art
Fig. 19-E, p. 526