What is "Air"?

Air is a non-homogenous mixture of gases, solid particles, and liquids; It consistes of gases and particles with small settling velocity that exhibit stability in a gravitational field.

Atmosphere layers

Troposphere 0-17 kilometers (¾ 11 miles)
Stratosphere 17-50
Mesosphere 50-90
Ionosphere 90-100

Nominal Composition

Major Components (99%) in % by w or fraction of total molecules*

Minor Components

Outdoor Air Pollutants

Sources and Types:

1. Carbon Oxides
   Carbon Monoxide (CO) & Carbon Dioxide (CO₂)
2. Sulfur Oxides
   Sulfur Dioxides (SO₂) & Sulfur Trioxide (SO₃)
3. Nitrogen Oxides
   Nitric Oxide (NO), Nitrogen Dioxide (NO₂), & Nitrous Oxide (N₂O)
4. Volatile Organic Compounds (VOCs)
   Most organic compounds - Example: Methane (CH₄), Methanol (CH₃OH), Benzene (C₆H₆), Chlorofluorocarbons (CFCs), formaldehyde (CH₂O), Propane (C₃H₈).
5. Suspended Particulate Matter (SPM)
   Solid and Liquid Particles both suspended in air. Example: dust soot, pollen, asbestos, ash, conglomerates, soil, salts, etc.
6. Photochemical Oxidants
   Ozone (O₃), Peroxide (H₂O₂), Hydroxide radicals (HO), aldehydes, etc. induced by electromagnetic energy from the Sun.
7. Radioactive Isotopes
   Radon-222, Iodine-131, Strontium-90, Plutonium-239, Potassium-40, as gases and suspended particles.
8. Heat
   Waste energy from fossil fuels; most energy sources and uses produce waste energy as heat, Example: cars, power plants, factories, homes.
9. Noise
   A byproduct of energy used in airplanes, cars, industry, lawn mowers, mechanical byproduct, radios, wind, electrical power line discharge, communications (electromagnetic overlap and clutter in communications).

Primary Pollutants (Anthropogenic)

• CO Carbon Monoxide
• CO₂ Carbon Dioxide
• NO Nitrogen Monoxide
• NO₂ Nitrogen Dioxide
• SO₂ Sulfur Dioxide
• Hydrocarbons (HCs)
• Suspended Particulates Matter (SPM)

Secondary Pollutants

• SO₃ Sulfite
• HNO₃ Nitric Acid
• H₂SO₄ Sulfuric Acid
• H₂O₂ Hydrogen Peroxide
• O₃ Tropospheric ozone

Outdoor Air Pollutants

Greenhouse Gas Emissions

Anthropogenic compositional alterations to the atmosphere:
From 1989 Compilation (from United Nations Reference)

Ozone depletion is the main effect, remember on average
each Cl atom destroys 100,000 (10⁵) O₃ molecules.
 
 

Why is CO a pollutant? a hazard?

Notes on importance:

Carbon Monoxide (CO) permanently binds with the Fe in Hemoglobin and permanently destroys that group

Particulates contribute to Smog and Lung disorders including cancer, haze, etc.

Hydrocarbons are greenhouse gases, contribute to Smog, are potentially toxic, and contribute to Smog and Lung disorders, haze, etc.

Local or Global Pollution -

Why is particulate pollution usually, local and gaseous pollution usually, global?

Atmospheric Sources

Primary forms are SO₂, H₂S, in the gas phase and SO₄^-2 in the condensed phases. From the burning of sulfur containing fuels. From bacterial reduction of SO₄^-2 to H₂S and sulfur containing proteins. Natural sources are volcanoes which produce large quantities of SO₂ and biological processes.

Notes on significance:

SO₂ and NO₂ (NOx) in the presence of water contribute to acid precipitation (acid rain) and photochemical smog. Acid Rain adversely effects agriculture, forests, aquatic habitats, and the weathering of building materials. SO₂ and NO 2aerosols impair visibility.

SO₂ concentrations as low as 0.1-0.2 ppm can incapacitate asthma or emphysema patients.

SO₂ combines with water to form sulfuric acid H₂SO ₄

Smog and Acid Deposition

Photochemical Smog is the interaction of electromagnetic radiation from the Sun and Primary Pollutants to form photochemical smog.

Sulfate particles are a major cause of haze and smog.
 

pH of rain is 5.0 to 5.6 due to CO₂ and water interaction as previously described, recall carbonate equilibrium.

Average eastern US precipitation is 4.3 with pHs < 3 and 2.5.

What are the consequences of "Acid Rain"?

• Toxic: It Kills - fish, plants, aquatic and terrestrial, microorganisms
• Damage to - Soil and Buildings (Limestone, CaCO3), Oxidizes metal and pits finishes like paint and coatings.
• Shifts Equilibrium in soil leaching Ca, Mg, K, and other cations.
• Weakens species making them susceptible to disease (AIDS type effect)
• Stunts growth of crops
• Proposed to be the third largest cause of lung disease in US after smoking and radon.

 

 

Indoor Air Pollution

Why?

Intensity of exposure
Levels reach 10 to 40 times those of outdoor air concentrations.

Estimates of 6,000 excess cancer deaths each year (excluding radon) and 20,000 excess cancer deaths from Radon alone.

Industrial exposure is estimated by the author and EPA to be 100,000 to 200,000 premature deaths each year to workers from indoor air in industrial settings.

Specific indoor air problems

• Radon
• Asbestos
• Formaldehyde
• Smoke
• Fumes (ever been to a dry-cleaning shop) ("nose analysis")
• Secondary Smoke
• Buildup of toxic fumes

Relationships between

• Vapor pressure
• Formaldehyde and building materials
• Particulate matter
• Building air exchange (Outdoor air "dilution", Why?)

What is the "Sick Building Syndrome"?
Why does it exist?
 

Effect of Air Pollution on Living Organisms

Humans

Cumulative effect of all of these pollutants is:

• Emphysema
• Respiratory tract irritation from gas and particles
• Asthma
• Heart trouble
• Lung cancer
• Irritation

Estimates:

Office of Technology Assessment estimates 50,000 premature deaths in US each year from respiratory or cardiac problems as result of air pollutants

American Lung Association estimates 120,000 US deaths each year from air pollution

EPA estimates air pollution costs $150 billion yearly in health care
$100 billion from indoor air pollution
$40 billion from automobiles

Plants

Chronic exposure to ozone, acid rain, sulfur, and nitrogen oxides may be most significant and synergistic.

Damage to leaves, roots, microorganisms (nitrogen fixing bacteria) etc. all weaken plant resistance to insects, frost, fungi, mosses, and disease.

Equilibration shifts in nutrients, aluminum ions, etc.

Aquatic Organisms Are Also At Risk

Acid precipitation is a major threat.

Low buffering capacity permits acid shock.

Why?

Hint: What is physiological pH and what does it control?
 
 

Liming is a temporary fix.

> ~ 75,000 lakes or streams world wide have been acidified to a substantial loss of aquatic life or are stressed.
 

Air Pollution Control and Clean Air Act of 1977 as revised in 1990

Established national ambient air quality standards (NAAQS) for 7 outdoor pollutants:

• suspended particulate matter
• sulfur oxides
• carbon monoxide
• nitrogen oxides
• ozone
• hydrocarbons
• lead

Why is nitrogen oxide unchanged and lead reduced?

Toxic Air Pollutants

A list of 600 toxic air pollutants was proposed

EPA has emission standards of 7 of the 600 toxic air pollutants:

• arsenic
• asbestos
• benzene
• beryllium
• mercury
• vinyl chloride
• radioactive isotopes

Methods of Pollution Control

Control of

Pollutants in general
Sulfur dioxide
Nitrogen oxides
Particulate matter emissions
Motor vehicle emissions
Troposphere ozone
Indoor air pollutants
+ 600 other pollutants (189 prime)
 
 

Prevention

Set limits, provide technology, provide incentive

Conservation of energy use in general and recycling and mass transit

Cleaner (low S fuel) and alternative Fuels and electric motors as alternative (batteries), Nuclear (fission, fusion?)

Modifying industrial plants and the engines for cleaner burning lower operating temperatures for NOx for example or collection devices in conjunction with reduced emission processes

Convert coal to gas first (eliminate particulate and S at same time)

Eliminating SO₂ and NOx will reduce O₃ in Troposphere from Photochemical reactions

Control Population?

Prevent indoor air pollutant buildup using air-to-air heat exchangers

Materials evaluation prior to use as building materials (indoor +) Methods of Pollution Control

Introduction of CaO (lime) into burning chamber for industrial burning

why?

To form Ca salts with SO₄^-2 and NO₃ -(chemical modification, neutralization & conversion to salts and products {gypsum CaSO₄} {CaSO₄ and H₂O used in plaster and wall board}

Higher smoke stacks to get above the inversion layer reduce local particulate, smog and pollution but let it fall elsewhere

Capture particulate and some pollutants using Electrostatic Precipitators, Baghouse Filters, Cyclone Separators, Wet Scrubbers.

Chemical Modification - example NOx and HCNO (isocyanic acid converts 99% of NOx to N₂ and water {not yet technically feasible commercially}.