1. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Air Pollution
Chapter 18
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

2. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Outline:
Natural Sources
Human-Caused Air Pollution
Conventional Pollutants
Unconventional Pollutants
Indoor Air Pollution
Climate and Topography
Effects of Air Pollution
Air Pollution Control
Clean Air Legislation
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

3. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
THE AIR AROUND US
Approximately 14 million metric tons of air pollution are released annually into the atmosphere in the US by human activities.
Worldwide emissions total around 2 billion metric tons.
Developed countries have been improving air quality, while air quality in developing world is getting worse.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

4. NATURAL SOURCES OF AIR POLLUTION
Natural Fires - Smoke
Volcanoes - Ash and Acid components
Sea Spray - Sulfur
Vegetation - Volatile organic compounds
Bacterial Metabolism - Methane
Dust
Pollen
Viruses and Bacteria
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

5. HUMAN-CAUSED AIR POLLUTION
Primary Pollutants - Released directly from the source.
Secondary Pollutants - Modified to a hazardous form after entering the air and mixing with other environmental components.
Fugitive Emissions - Do not go through smokestack.
Dust from human-activities.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

6. Conventional Pollutants
US Clean Air Act designated seven major (conventional or criteria) pollutants for which maximum ambient air levels are mandated.
Sulfur Dioxide
Carbon Monoxide
Particulates
Hydrocarbons
Nitrogen Oxides
Photochemical Oxidants
Lead
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

7. Conventional Pollutants
Sulfur Compounds
Natural sources of sulfur in the atmosphere include evaporation from sea spray, volcanic fumes, and organic compounds.
Predominant form of anthropogenic sulfur is sulfur-dioxide from fossil-fuel combustion.
Annual Emissions: 114 million metric tons
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

8. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Sulfur Compounds
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

9. Conventional Pollutants
Nitrogen Compounds
Nitrogen oxides are reactive gases formed when nitrogen is heated above 650o C in the presence of oxygen, or when nitrogen compounds are oxidized.
Annual Emissions: 230 million metric tons
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

10. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Nitrogen Compounds
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

11. Conventional Pollutants
Carbon Oxides
Predominant form of carbon in the air is carbon dioxide.
Increasing levels due to human activities.
Annual Emissions: 8-10 billion metric tons
Carbon monoxide is a colorless, odorless, toxic gas produced by incomplete fuel combustion.
Annual Emissions: 1 billion metric tons
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

12. Conventional Pollutants
Metals
Many toxic metals occur as trace elements in fuel.
Lead Emissions: 2 million metric tons.
Mercury
Bioaccumulation in aquatic ecosystems.
Nickel, beryllium, cadmiuym, arsenic…
Halogens (Fluorine, Chlorine, Bromine)
CFC’s
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

13. Conventional Pollutants
Particulate Matter
Atmospheric aerosols (solid or liquid)
Respirable particles smaller than 2.5 micrometers are among most dangerous.
Volatile Organic Compounds
Organic chemicals
Generally oxidized to CO and CO2.
Of 188 air toxics listed in Clean Air Act, two-thirds are VOC’s.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

14. Conventional Pollutants
Photochemical Oxidants
Products of secondary atmospheric reactions driven by solar energy.
Ozone formed by splitting nitrogen dioxide.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

15. Unconventional Pollutants
EPA sets emissions standards for unconventional or non-criteria pollutants that are considered especially hazardous.
Asbestos, benzene, beryllium, etc.
Most have no natural source in the environment.
Aesthetic Degradation
Noise, odor, light pollution.
Reduce quality of life.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

16. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Indoor Air Pollution
EPA found indoor concentrations of toxic air pollutants are often higher than outdoor.
People generally spend more time indoors.
Smoking is the most important air pollutant in the US.
400,000 die annually from a disease related to smoking.
Associated costs are estimated at $100 billion annually.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

17. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Indoor Air Pollution
Less Developed Countries also suffer from indoor air pollution.
Organic fuels make up majority of household energy.
Often burned in smoky, poorly ventilated heating and cooking fires.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

18. CLIMATE AND TOPOGRAPHY
Inversions
Temperature inversions occur when a stable layer of warm air overlays cooler air, reversing the normal temperature decline with increasing height, and preventing convection currents from dispersing pollutants.
Cold front slides under warm air mass.
Cool air subsides down slope.
Rapid nighttime cooling in a basin.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

19. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Inversions
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

20. Dust Domes and Heat Islands
Sparse vegetation and large amounts of concrete and glass create warm, stable air masses, heat islands, over large cities.
Concentrates pollutants in a “dust dome”.
Rural areas downwind from major industrial areas often have significantly decreased visibility and increased rainfall.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

21. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Long-Range Transport
Fine aerosols can be carried great distances by the wind.
Increasingly, sensitive monitoring equipment has begun to reveal industrial contaminants in places usually considered among the cleanest in the world.
Contaminants trapped by winds at the north pole, concentrate at high latitudes and eventually fall out as snow and ice and enter the food chain.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

22. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Long-Range Transport
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

23. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Stratospheric Ozone
Discovered in 1985 that stratospheric ozone levels were dropping rapidly during September and October.
Occurring since at least 1960.
At ground-level, ozone is a pollutant, but in the stratosphere it screens UV radiation.
A 1% decrease in ozone results in a 2% increase in UV rays reaching the earth.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

24. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Stratospheric Ozone
Circumpolar vortex isolates Antarctic air and allows stratospheric temperatures to drop and create ice crystals at high altitudes.
Absorb ozone and chlorine molecules.
When sun returns in the spring, energy liberates the chlorine allowing the depletion process to proceed rapidly.
CFC’s believed to be main culprit.
Persist for decades.
Production eliminated in 1996.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

25. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
CFC Production
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

26. EFFECTS OF AIR POLLUTION
Human Health
EPA estimates each year 50,000 people die prematurely from illnesses related to air pollution.
Likelihood of suffering ill health is related to intensity and duration of exposure.
Inhalation is the most common route, but absorption through the skin and consumption via food can also occur.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

27. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Human Health
Bronchitis
Persistent inflammation of airways in the lung that causes mucus build-up and muscle spasms constricting airways.
Can lead to emphysema - irreversible obstructive lung disease in which airways become permanently constricted and alveoli are damaged or destroyed.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

28. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Plant Pathology
Chemical pollutants can directly damage plants, or can cause indirect damage by disrupting normal growth and development patterns.
Certain environmental factors have synergistic effects in which the injury caused by the combination is more than the sum of the individual exposures.
Pollutant levels too low to cause visible effects may still be damaging.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

29. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Acid Deposition
pH and Atmospheric Acidity
pH scale ranges from 0-14.
7 = Neutral; <7 = Acidic; >7 = Basic
Unpolluted rain generally has ph of 5.6.
Carbonic acid from atmospheric CO2.
In industrialized areas, anthropogenic acids in the air often outweigh natural sources of acid.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

30. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Acid Deposition
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

31. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Acid Deposition
Aquatic Effects
Thin, acidic soils and oligotrophic lakes of southern Norway and Sweden have been severely affected by acid deposition.
Generally, reproduction is the most sensitive stage in fish life cycles.
In early 1970’s, evidence began to accumulate suggesting air pollutants are acidifying many NA lakes.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

32. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Acid Deposition
Forest Damage
Air pollution and depositions of atmospheric acids are believed to be important causes of forest destruction in many areas.
Buildings and Monuments
Limestone and marble are destroyed by air pollution at an alarming rate.
Corroding steel in reinforced concrete weakens buildings, roads, and bridges.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

33. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
AIR POLLUTION CONTROL
Particulate Removal
Remove particles physically by trapping them in a porous mesh which allows air to pass through but holds back solids.
Electrostatic Precipitators - Fly ash particles pick up electrostatic charge as they pass between large electrodes in waste stream, and accumulate on collecting plate.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

34. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Sulfur Removal
Fuel Switching
Switch from soft coal with a high sulfur content to low sulfur coal.
Change to another fuel (natural gas).
Limestone Injection
Can reduce sulfur emissions by 90% by mixing crushed limestone with coal before it is fed into a boiler.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

35. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Sulfur Removal
Flue Gas Desulfurization
Inject crushed limestone into stack gas stream to remove sulfur after combustion.
Dry Alkali Injection
Sulfur Recovery Process
Use catalytic converters to oxidize or reduce sulfur and create chemical compounds that can be collected and sold.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

36. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Air Pollution Control
Nitrogen Oxide Control
Best method is to prevent creation.
Staged Burners
Selective Catalysts
Hydrocarbon Control
Use closed systems to prevent escape of fugitive emissions.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

37. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
CLEAN AIR LEGISLATION
Clean Air Act (1963) - First national air pollution control.
Clean Air Act (1970) rewrote original Act.
Identified critical pollutants.
Established ambient air quality standards.
Primary Standards - Human health
Secondary Standards - Materials, environment, aesthetic and comfort.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

38. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Clean Air Act
Revision (1990) - Included provision for:
Acid Rain
Urban Smog
Toxic Air Pollutants
Ozone Protection
Marketing Pollution Rights
Volatile Organic Compounds
Lead
Revision (1997) - Stricter standards
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

39. CURRENT AND FUTURE CONDITIONS
In the United States, air quality has improved dramatically in the last decade in terms of major large-volume pollutants.
Cities where pollution is largely from traffic still have serious air quality problems.
Major metropolitan areas of many developing countries are growing at explosive rates, and environmental quality is very poor.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

40. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Summary:
Natural Sources
Human-Caused Air Pollution
Conventional Pollutants
Unconventional Pollutants
Indoor Air Pollution
Climate and Topography
Effects of Air Pollution
Air Pollution Control
Clean Air Legislation
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

41. Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.