1. Air Pollution

2. Composition Nitrogen: 78.1% Oxygen: 20.9% Other Gases: Argon : 0.9%
CO2 : ~370 ppm: Green House Gas
Methane: Green House Gas
Ozone: blocks UV radiation
Dust: solid particles in the atmosphere
Water Vapor: a major player in atmospheric circulations
Since water vapor is lighter than the atmosphere. Introduction of water vapor causes vertical movement (convection) in the atmosphere

3. Structure
Troposphere: 0-11 km elevation, the weather layer, temp. drops with elevation
Tropopause
Stratosphere km, little vertical motion, contains ozone layer, Temp rises with elevation
Stratopause
Mesosphere: >45 km

5. Ambient Air Pollution:
Ground level tropospheric air pollution. It is air pollution all around us.
Criteria Air Pollution:
Originated with the Clean Air Act of 1970
EPA identified six most serious pollutant in the ambient air
CO, O3, SO2, NO, PM (particulate matter) and Pb (Lead)
VOC (Volatile Organic Pollutants):

6. Criteria Air Pollutant
These are produced in large amounts – hence higher risk
Exhausts from motor vehicles account for about half of these emissions
In many major cities, criteria air pollutants cause eye and respiratory irritation, head ache and other ailments.

7. Outdoor Pollution
Indoor Pollution
Primary Pollution
Secondary Pollution

8. Carbon Monoxide (CO)
Product of incomplete combustion of carbon
Accounts for 50% of all air pollutants
Accounts for 11% of all hospital admission of elderly patients for congestive heart failure
Iron atom in hemoglobin in blood picks up oxygen from lungs and takes it to the cells. CO has 250 X more affinity for the iron atom compared to Oxygen
Organs get less oxygen: heart and brain gets affected first
Headache dizzinessfatigue, drowsiness  coma  death
US ambient air standard for CO is 9 ppm averaged over 8 hours. If it exceeds one time in a year , the area is violating standards.

9. Ground level Ozone Ozone O3 has three oxygen atoms
Major component of photochemical smog (which also contain nitrates and nitrogen oxides)
Nox + VOC  (Sunlight, High Temp, stagnant air O3
Automobiles are the main producers of precursors, also power plants, aeroplanes
EPA considers Ozone as the “most … intractable air pollutant in urban areas”.
Effects on People: see the table
Effects on Plants and trees: causes more damage to plants than all other air pollutants combined
Crop loss in USA 5-10%
World wide 35% of the crops grow in areas with high O3
More harmful when combined with other pollutants like acid rain
Trees and forests are also adversely affected

10. Ozone is a major component of SMOG
Smog = unhealthy mixtures of air pollutants over urban areas
1. Industrial (gray air) smog = industries burn coal or oil
2. Photochemical (brown air) smog = Produced by light-driven reactions of primary pollutants & normal atmospheric compounds
Irritates eyes, noses, and throats
Vehicle inspection programs in the U.S. have decreased smog
Nitrogen oxides (give it brown hazy color) + VOCs + heat + sunlight
= O3 + other photochemical oxidants + aldehydes

11. Industrial smog
Photochemical smog
17.16

12. Ozone Levels Concentration (ppm) Air Quality <0.05
Good: No health impact expected
0.051 – 0.100
Moderate: Unusually sensitive people should consider prolonged exertion outdoors
0.101 – 0.150
Unhealthy for sensitive group: Active children and adults with asthma or other respiratory diseaes should avoid prolonged outdoor exertion
Unhealthy: Active children and adults and those with respiratory diseases should follow the advise above. Children should limit prolonged outdoor exertion
0.201 – Alert
Very Unhealthy: Active children and adults, and those with respiraory diseases should avoid all outdoor exertion. Others, especially children should limit outdoor exertions

13. How to reduce Ozone pollution?
Reduce NOx and VOC emissions from Automobiles
1970 CAA – emissions fell 90%
But more autos and increased miles driven = high Nox and VOC
New Ozone standard
Low VOC and NOx does not necessarily reduce O3
Between 1990 to 1992, # of cities in US exceeding old O3 standard (<.12 ppm) fell from 97 to 56
Reduced emissions from power plants, vapor recovery nozzles in Gas stations, cleaner burning gasoline
Restricting Formaldehyde emissions because Formaldehyde causes more O3 formation than other VOCs
New EPA standard : 0.08 ppm – 1/3rd of US cities do not comply even with the old standard (0.12 ppm) – LA has > 0.20 ppm on days

14. Sulfur Gases >50 million tons of SO2 emitted worldwide
2/3rd from combustion of coal in power plants
Rest mostly from Petroleum refining, smelting
Natural Sources: sea water, bacteria, planktons, plants
Volcanic eruption: Mt Pinatubo (1991) ejected 20 million tons – caused global cooling

15. Sulfur dioxide (SO2)
SO2 gas reacts with moisture to form sulfuric acid which causes irritation and aggravates asthma, heart disease. Mucous membrane in eye, lungs affected
Forms aerosols (suspension of fine liquid or solid particles in air) of sulfuric acid (wet condition) or sulfates (dry condition) – can inflame lungs if inhaled
Environmental Effects:
Forms blue haze that blocks sunlight
Causes acid deposition (acid rain)
Harms stratospheric O3

16. Nitrogen Oxides (NOx)
NO (nitric oxide), NO2 (nitrogen dioxide), N2O (nitrous oxide)
Sources: at high temp atmospheric N2 combines with O2
Motor vehicles (50%), Electric utilities (25-30%), industrial furnaces (14%)
Natural sources: Lightning, soil microbes, volcanoes
Same as SO2: irritation, haze, acid rain, global cooling, ozone destruction
But also is precursor of Ozone formation – SO2 is not
Deposited on earth acts as a plant nutrient – can be very harmful in high concentrations

17. Particulate Matter (PM)
Solids suspended in air
Accounts for 10% of US air pollution
Can vary in composition and size
Sulfates, nitrates, metals, dust, biological matters
Gaseous pollutants can condense into PMs
Caused silicosis, black lung diseases (coal miners), mesothelioma from asbestos
Coarser PM can be sneezed out, PM 10 is regulated by EPA, PM 2.5 even more dangerous--- can cause inflamation in Lungs. Very fine PM can cause cancer
Causes Haze , lowers visibility– can cause other problems

18. Sources: PM10 = dust from farms, mines, or roads, pollens
PM2.5 = mostly from combustions– diesel motor vehicles, electric power plants, industrial operations like steel mills, fly ash
Construction sites, agricultural activities, wood burning stoves
Chloride salts in coastal areas

19. We don’t know which component is most harmful
EPA standard :
PM10 < 50 μg/m3. PM2.5 <15 μg/m3
PM2.5 contains different chemicals in east coast comapred to west coast
We don’t know which component is most harmful
Sulfates, nitrates, soot, metal oxides?
Controlling combustion sources

20. Lead Causes Brain damage, nervousness, apathy
Inner city children more at risk
Tetraethyl Lead was used as a octane booster in gasoline
Lead was used in paints
Now both use banned with dramatic reduction of lead in atmosphere and in average blood levels
Lead mobilized many years ago is still a problem:
Old paints, solder of old water pipes, roadside soil contaminated by leaded gasoline…
Other pollutants like Hg, Cd, Pb, Zn, As can be of concern near mines and smelters

22. Volatile Organic Chemicals (VOC)
Combustion sources: Motor vehicles, aeroplanes, farm machineries, lawn mowers..
Incomplete combustion, idling
Evaporation during filling of gas tanks
Non-combustion sources:
Petroleum refineries, chemical plants
Dry cleaners
Paint shops, garages, print shops
Bakeries – emit ethanol formed by action of yeast
Sewage treatment plants, composting
Natural Sources: Trees emit VOCs. 90% of VOCs in Maine is from Trees.
Terpene can contribute to Ozone formation
Reducing VOC emission: CAA – VOC dropped by 30% between 1970 and 1985

25. Acid Rain
Any rain more acidic than normal rain (pH=5). Carbonic, Sulfuric and Nitric acids
SO2 dissolves in water to form Sulfuric acid: main ingredient of acid rain. NOx  Nitric acid. CO2 Carbonic acid
Industrialized areas more affected. pH=4.2 in US Northeast
In the United States, roughly 2/3 of all SO2 and 1/4 of all NOx come from electric power generation that relies on burning fossil fuels, like coal. 
Granitic terrains more affected than limestone terrains
Affects plant growth, contaminates lakes and groundwater, man made structures, cause algal blooms, releases heavy and toxic metals from sediments

26. Acid deposition
Originates from burning fossil fuels that release sulfur dioxide and nitrogen oxides
These compounds react with water to form sulfuric and nitric acids

27. Acidic precipitation in the U.S.

28. Acid Deposition: Effect of Life in WaterpH
Effect of Life in water 6
Snails and Crayfish begin to die 5
Fish eggs do not hatch, some fish die
4.5 to 5
Fish species like Bass and Trout begin to die 4
Many flies and frogs begin to die

29. US emission of criteria pollutants, 2006
In 2006, the U.S. emitted 137 million tons of the 6 major pollutants

30. Health Effects
Respiratory diseases = damage to tissue (asthma, bronchitis, emphysema)
½ of all lungs examined in autopsies in US show damage
Lead to lung cancer
Heart disease, immune suppression, reduced mental function
1 in 5 people live with dangerously polluted air
Reduced life expectancy
5-10 yrs if you live in LA
(150 days of hazardous breathing)
24, 000 people/yr die in the US
Los Angeles, CA

31. Air pollution has decreased since 1970
Total emissions of the 6 monitored pollutants have declined
Cap-and-trade program for SOx.
Enabled the 110 most polluting power plants to buy and sell SO2 pollution rights.
But CO2 emissions have been increasing

32. Areas in the U.S. fail air quality standards

33. Ozone Hole
Ozone is harmful at Ground level At 15 km above surface UV ray reacts with Oxygen to produce Ozone. This Ozone absorbs UV ray and shields earth’s surface
1% reduction in ozone causes 3% rise in skin cancer in light-skinned people plus increased cataract, melanoma, gene mutation, immune system damages
UVA: longest wavelength: not damaging UVC: shortest wavelength: highly damaging, absorbed by oxygen UVB: intermediate wavelength: absorbed by Ozone

34. Destruction of Ozone
Ozone in the upper atmosphere can be destroyed by the exhaust of hi-altitude aircrafts and more seriously by
CFCs(Chlorofluorocarbons) which were used as a refrigerant and in aerosol spray cans (e.g., Freon)
40 billion lbs of CFC produced since 1931 and 90% of this released to the atmosphere
The released CFC either dissolves in seawater or go into Troposphere where they remain for many decades and are harmless
Some of the CFC escape to stratosphere, absorb UV ray and releases Chlorine which act as a catalyst to break Ozone molecule

35. Destruction of Ozone Chlorine + Ozone = ClO(Chlorine Monoxide) + O2
A single chlorine atom can destroy 100,000 ozone molecules
ozone hole is more pronounced in polar regions
In polar stratosphere, extreme cold removes nitrogen compounds, which normally inactivate chlorine, from the stratosphere
Release of reactive chlorine is also catalyzed by fine ice crystals in stratosphere
At present both the Arctic and Antarctic are affected by ozone hole
Sulfate aerosols as from Mt Pinatubo also destroys Ozone layer

36. Ozone Hole
UV rays reaching Antarctica each spring has increased from 20 to 200% every year since 1980s
Production of algae and bacteria in contact with seawater has decreased by 15% since the late 1980s
Marine Phytoplanktons are severely stressed
This in turn, will affect animals higher in the food chain.

37. Ozone Hole

38. Ozone Hole over Antarctica and N. America

39. Present scenario Montreal Protocol (1987, 1990)
Signed by more than 70 nations
Stipulates phasing out of CFCs and other ozone depleting compounds by 2000
Hesitancy on part of China
Substitutes not totally safe
Latest data indicate that ozone hole is not expanding

40. CO2 needs to be added to the list!
Not regulated as a pollutant under the U.S. Clean Air Act.
But most emissions are CO2
A greenhouse gas
Contributes to global climate change
In the US…

41. Sources of C02 US emissions 40 % Petroleum products 34 % coal
20 % natural gas

42. Greenhouse Effect In a greenhouse, light enters but IR cannot escape
CO2 in atmosphere allows light rays to enter but traps IR
CO2 % in atmosphere has increased from 280 ppm in pre-Industrial time to present day value of ppm (2003 data)

44. Rise in atmospheric CO2 in the last two decades

45. Greenhouse Effect: Is it Real?
How much CO2=How much rise of T?
More T = more evaporation = more cloud = Less Temp…
Real rise or natural fluctuation?
Data for the last 10ka indicate upto 6 °C fluctuation
Little ice age (1450 – 1850)

46. Methane (CH4) concentration
Global Temperature Rise
Methane (CH4) concentration
ppb

47. Other Greenhouse Gases
Methane, water vapor, nitrous oxide
Rice paddy, extraction of fossil fuel, raising of live stock (bovine flatulence) cause increase in methane
Cutting of forests kills CO2 sink
Some effects might be opposite of CO2: SO2
Temperate regions more resilient
Colder climate will have longer growing season
Marginal areas to be hard hit
More flooding, heat waves…

48. Greatest air pollution problem: Global Warming

49. Evidence to Support Global Warming
Intergovernmental Panel on Climate Change (IPCC)
An international panel of scientists and government officials established in 1988
Generated reports on the synthesis of scientific information concerning climate change
4th Assessment report 2007
Documents observed trends in surface temperature, precipitation patterns, snow and ice cover, sea levels, storm intensity
The IPCC concluded that it is more than 90%
likely that most global warming is due to humans
The Debate over climate change is over
84% of people surveyed think humans contribute to global warming
Predicts future changes

50. Temperatures will rise 0.2 degree Celsius per decade

51. Greenhouse Effect: Problems
Rise of temperature : Drier climate?
Melting of Ice Caps: ultimate reduction of soil moisture (up to 40%)
If all the ice melted sea level will rise by 75m inundating 20% of the Earth’s land area. No Florida!!
Even a partial melting of Antarctica ice cap will raise sea level by 3 to 6m. Fear of calving from Ross Ice Shelf

53. Rising sea levels
IPCC predicts mean sea level to be cm (7-23 in) higher than today’s at the end of the 21st century

54. Predictions from two models
By 2030, Illinois will have a climate like Missouri’s.
By 2090, it will have a climate like Oklahoma’s.
Green = Canadian model
Blue = Hadley model

55. Halting emissions California’ s Global Warming Solutions Act
Cut greenhouse gas emissions 25% by 2020
10 NE states launched the Regional Greenhouse Gas Initiative (RGGI) in 2007
cap-and-trade program for C emissions from power plants

56. Fig , p. 371

57. Kyoto Protocol Conference: Dec 1-11, 1997 in Kyoto, Japan
Six Greenhouse gases were targeted (CO2, CH4, NOx, CFC-substitutes)
Their emission to be reduced below 1990 levels as follows:
EU: 8%, US: 7%, Japan 6%
The reduction will be done in a 5 year period between
Emission can be traded in global market
Creation of carbon sinks like afforestation can be balanced against emission
Developing countries to benefit from “clean” technology
The protocol will be open for signature in March, 1998, has to be ratified by countries producing 55% of the emissions: reached in 2004 after Russia signed it.
Entered into force: Feb 16, 2005 US pulled out of it in 2001