1. Atomosphere & Air Pollution& Solid Waste
Miller Chapters 18 & 19 & 21
Many Slides from
Mark Ewoldsen, Ph.D.
La Canada HS

2. Take a minute to view our majestic planet

3. Natural sources of air pollution
dust storms
volcanoes
fires

7. The atmosphere is composed of nitrogen (N2) 78%, oxygen (O2) 21%, argon (Ar) 93%, water vapor(H2O), and a number of trace gases

8. 2 H2 + O2   -->   2 H2O
Write the equations for photosynthesis and respiration

9. Pollutant
Chemical Reaction
Carbon Monoxide (CO)
2 C + O CO
Carbon Dioxide (CO 2)
C + O CO 2
Nitric Oxide (NO)
N O NO
Nitrogen dioxide (NO2)
2NO + O NO 2
Sulfur dioxide (SO2)
S + O SO2

10. Artificial sources of air pollution
Human-caused air pollution includes:
Point sources = specific spots where large amounts of pollution are discharged (factory smokestacks)
Non-point sources = diffuse, often made up of many small sources (charcoal fires from thousands of homes)

11. Artificial sources of air pollution
Human-caused air pollution includes:
Primary pollutants = emitted into troposphere in a directly harmful form (soot, carbon monoxide)
Secondary pollutants = produced when primary pollutants and chemicals already present in the atmosphere to form new harmful chemicals (ozone in troposphere)

12. Criteria Air Pollutants
EPA uses six "criteria pollutants" as indicators of air quality
Nitrogen Dioxide: NO2
Ozone: ground level O3
Carbon monoxide: CO
Lead: Pb
Particulate Matter: PM10 (PM 2.5)
Sulfur Dioxide: SO2
Volatile Organic Compounds: (VOCs)
EPA established for each concentrations above which adverse effects on health may occur

13. Primary Pollutants CO CO2 Secondary Pollutants SO2 NO NO2 SO3
Most hydrocarbons
HNO3
H2SO4
Most suspended
particles
H2O2 O3
PANs
SO4 2 –
Most
NO3 –
and
salts
Natural
Sources
Stationary
Mobile

14. Human Impact on Atmosphere
Burning Fossil Fuels
Using Nitrogen fertilizers and burning fossil fuels
Refining petroleum and burning fossil fuels
Manufacturing
Adds CO2 and O3 to troposphere
Global Warming
Altering Climates
Produces Acid Rain
Releases NO, NO2, N2O, and NH3 into troposphere
Produces acid rain
Releases SO2 into troposphere
Releases toxic heavy metals (Pb, Cd, and As) into troposphere
air/products.html

15. Nitrogen Dioxide (NO2)
Properties: reddish brown gas, formed as fuel burnt in car, strong oxidizing agent, forms Nitric acid in air
Effects: acid rain, lung and heart problems, decreased visibility (yellow haze), suppresses plant growth
Sources: fossil fuels higher temperatures, power plants, forest fires, volcanoes, bacteria in soil
Class: Nitrogen oxides (NOx)
EPA Standard: ppm

16. Air Pollution over China-The Asian Black Cloud

17. Ozone (O3)
Properties: colorless, unpleasant odor, major part of photochemical smog
Effects: lung irritant, damages plants, rubber, fabric, eyes, 0.1 ppm can lower PSN by 50%,
Sources: Created by sunlight acting on NOx and VOC , photocopiers, cars, industry, gas vapors, chemical solvents, incomplete fuel combustion products
Class: photochemical oxidants

18. Ozone (O3)
10,000 to 15,000 people in US admitted to hospitals each year due to ozone-related illness
Children more susceptible
Airways narrower
More time spent outdoors

20. Carbon Monoxide (CO)
Properties: colorless, odorless, heavier than air, % of atmosphere
Effects: binds tighter to Hb than O2, mental functions and visual acuity, even at low levels
Sources: incomplete combustion of fossil fuels % from auto exhaust
Class: carbon oxides (CO2, CO)
EPA Standard: 9 ppm
5.5 billion tons enter atmosphere/year

21. Lead (Pb) Properties: grayish metal
Effects: accumulates in tissue; affects kidneys, liver and nervous system (children most susceptible); mental retardation; possible carcinogen; 20% of inner city kids have [high]
Sources: particulates, smelters, batteries
Class: toxic or heavy metals
EPA Standard: 1.5 ug/m3
2 million tons enter atmosphere/year

22. Suspended Particulate Matter (PM10)
Properties: particles suspended in air (<10 um)
Effects: lung damage, mutagenic, carcinogenic, teratogenic
Sources: burning coal or diesel, volcanoes, factories, unpaved roads, plowing, lint, pollen, spores, burning fields
Class: SPM: dust, soot, asbestos, lead, PCBs, dioxins, pesticides
EPA Standard: 50 ug/m3 (annual mean)

23. Sulfur Dioxide (SO2) Properties: colorless gas with irritating odor
Effects: produces acid rain (H2SO4), breathing difficulties, eutrophication due to sulfate formation, lichen and moss are indicators
Sources: burning high sulfur coal or oil, smelting or metals, paper manufacture
Class: sulfur oxides
EPA Standard: 0.3 ppm (annual mean)
Combines with water and NH4 to increase soil fertility

24. VOCs (Volatile Organic Compounds)
Properties: organic compounds (hydrocarbons) that evaporate easily, usually aromatic
Effects: eye and respiratory irritants; carcinogenic; liver, CNS, or kidney damage; damages plants; lowered visibility due to brown haze; global warming
Sources: vehicles (largest source), evaporation of solvents or fossil fuels, aerosols, paint thinners, dry cleaning
Class: HAPs (Hazardous Air Pollutants)
Methane
Benzene
Chlorofluorocarbons (CFCs), etc.
Concentrations indoors up to 1000x outdoors
600 million tons of CFCs

26. Other Air Pollutants Carbon dioxide ChloroFluoroCarbons Formaldehyde
Benzene
Asbestos
Manganese
Dioxins
Cadmium
Others not yet fully characterized

27. Formation & Intensity Factors
Local climate (inversions, air pressure, temperature, humidity)
Topography (hills and mountains)
Population density
Amount of industry
Fuels used by population and industry for heating, manufacturing, transportation, power
Weather: rain, snow,wind
Buildings (slow wind speed)
Mass transit used
Economics

29. Smog Forms ...when polluted air is stagnant
(weather conditions, geographic location)
Los Angeles, CA

30. Primary Pollutants CO CO2 Secondary Pollutants SO2 NO NO2 SO3
Most hydrocarbons
HNO3
H2SO4
Most suspended
particles
H2O2 O3
PANs
SO4 2 –
Most
NO3 –
and
salts
Natural
Sources
Stationary
Mobile

31. Photochemical Smog UV radiation H2O + O2 Primary Pollutants
NO2 + Hydrocarbons
Secondary Pollutants
HNO3 O3
nitric acid ozone
Photochemical Smog
Auto Emissions

33. Air Pollution Results

36. Six “criteria pollutants”
Emissions of all of these, especially lead and carbon monoxide, have substantially declined since 1970.

37. Volatile organic compounds
“VOCs” are regulated by many governments.
Large group of potentially harmful carbon- containing chemicals used in industrial processes.
Hydrocarbons are one example.
About half are human-made, half natural.
VOCs contribute to smog, produce secondary pollutants.

38. Toxic air pollutants
Toxic air pollutants = chemicals known to cause serious health or environmental problems
Include substances known to cause cancer and reproductive defects, and substantial ecological harm
Most produced by human activities
188 toxic air pollutants are regulated under the 1990 Clean Air Act.

39. Industrial smog Smog from industrial pollution, fossil-fuel combustion
The kind that blanketed London in 1952
“Gray air smog”
Contains soot, sulfur, CO, CO2…

40. Industrial smog
The U.S. had its own “killer smog” from industrial pollution. Shown is Donora, Pennsylvania, in 1948, at mid-day. Subsequent demand for legislation against pollution made U.S. air much cleaner.

41. Industrial smog Chemistry of industrial smog:
• Burning sulfur-rich oil or coal creates SO2, SO3, sulfuric acid, ammonium sulfate.
• Carbon leads to CO2 and CO.

42. The star pollutants mentioned are sulfur dioxide, nitrogen dioxide and particulates caused by an assortment of methods such as burning fossil fuels, bi products of power plants or even particles that include lead, dust ammonia and other harmful substances

43. Photochemical smog Smog from reaction of sunlight with pollutants
The kind that blankets so many American cities today
“Brown air smog”
Contains tropospheric ozone, NO2, VOCs, 100 more…
Hot sunny days in urban areas create perfect conditions.

44. Photochemical smog
Mexico City and many of the world’s cities suffer from the brownish haze of photochemical smog.
Inversion layers and mountains can trap smog over certain cities.

45. Photochemical smog Chemistry of photochemical smog:
Nitric oxide starts a chain reaction.
Reaction with sunlight, water vapor, hydrocarbon, results in over secondary pollutants.

46. Stratospheric ozone depletion
NASA Video on Ozone Hole
Ozone at low altitudes = beneficial layer protecting us from UV radiation
Ozone layer— ~ 12 parts per million in lower stratosphere—is enough to absorb UV and protect us.
But in the 1960s scientists noticed ozone concentrations were dropping.

47. Stratospheric ozone depletion
In 1974, Sherwood Rowland and Mario Molina pegged the blame on chlorofluorocarbons (CFCs).
They won the Nobel Prize for this scientific detective work.
CFCs = human-made molecules in which hydrogens of hydrocarbons are replaced by chlorine and fluorine atoms
Mass-produced by industry, in refrigerants and consumer products like aerosol sprays

48. Stratospheric ozone depletion
CFCs persist in the stratosphere. They split oxygen atoms off ozone (O3) to form oxygen (O2).
1 Cl atom can split many O3 molecules

49. Stratospheric ozone depletion
In 1985, the “ozone hole” was detected over Antarctica.
Ozone levels had declined 40–60% over the previous decade.

50. Stratospheric ozone depletion
Scientists worried about the effects of extra cancer-causing UV on people, organisms, ecosystems.
The ozone hole (blue) reached its greatest extent in September 2000 (satellite imagery).

51. Stratospheric ozone depletion
The Dobson spectrophotometer, invented in 1924, can infer ozone concentrations from the ground, and helped scientists detect ozone depletion.

52. Stratospheric ozone depletion
In 1987, over 180 nations signed the Montreal Protocol, which restricted CFC production globally.
Follow-up agreements strengthened the pact.
Today CFC levels are down, and stratospheric ozone is starting to recover.
The Montreal Protocol is one of the biggest environmental success stories of our time.
We have apparently avoided a major environmental problem.

53. Stratospheric ozone depletion
Reasons for success of the Montreal Protocol:
• Government and industry cooperated on finding solutions (cheap replacement technologies for CFCs), so battles typical to environmental debates were minimized.
• Protocol was implemented with “adaptive management”—ability to fine-tune actions as time goes on, in response to new data or conditions.

54. Clean Air Act legislation
Major air pollution legislation:
Clean Air Act of 1970:
Set stricter standards than previous laws
Imposed emissions limits
Provided research funds
Enabled citizens to sue violating parties
Clean Air Act of 1990:
Strengthened previous regulations
Introduced emissions trading for sulfur dioxide