19 Air Pollution
Overview of Chapter 19
Atmosphere as a Resource Types and Sources of Air Pollution Effects of Air Pollution Controlling Air Pollution in the US Ozone Depletion in the Stratosphere Acid Deposition Air Pollution Around the World Indoor Air Pollution
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Atmospheric pressure (millibars)0 200 400 600 800 1,000
120
110
100
90
80
70
60
50
40
30
20
10
0(Sea
Level)–80 –40 0 40 80 120
Pressure = 1,000millibars atground levelTemperature (˚C)
Alt
itu
de
(kilo
met
ers)
Alt
itu
de
(mile
s)
75
65
55
45
35
25
15
5
Thermosphere
Heating via ozone
Mesosphere
Stratosphere
Ozone “layer”Heating from the earth
Troposphere
Temperature
PressureLayers of the Atmosphere
Highlights: Pressure decreases with altitude until it reaches zeroTroposphere is the layer we live in; mostly N and O; weather; colder as you go upStratosphere: has the ozone layer; warmer as you go upEnvironmental science focuses mostly on those two layers
Atmosphere as a Resource
Atmospheric Composition Nitrogen 78.08% Oxygen 20.95% Argon 0.93% Carbon dioxide 0.04%
Ecosystem services( what it does for the ecosystem) Blocks UV radiation Moderates the climate Redistributes water in the
hydrologic cycle
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Air Pollution - Terminology
Air Pollution Chemicals added to the atmosphere by natural
events or human activities in high enough concentrations to be harmful
Two categories Primary Air Pollutant
Harmful substance emitted directly into the atmosphere Secondary Air Pollutant
Harmful substance formed in the atmosphere when a primary air pollutant reacts with substances normally found in the atmosphere or with other air pollutants
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Major Air Pollutants
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Major Classes of Air Pollutants
Particulate Material Nitrogen Oxides Sulfur Oxides Carbon Oxides Hydrocarbons Ozone
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Particulate Material
Thousands of different solid or liquid particles suspended in air. Small and light enough to remain suspended in atmosphere for short periods to long periods Includes: soil particles, soot, lead, asbestos, sea salt, and sulfuric acid droplets
Major human sources: Burning coal in power and industrial plants (40%), burning diesel and other fuels in vehicles (17%), agriculture (plowing, burning off fields), unpaved roads, construction. Health effects: Nose and throat irritation, lung damage, and bronchitis; aggravates
bronchitis and asthma; shortens life; toxic particulates (such as lead, cadmium, PCBs, and dioxins) can cause mutations, reproductive problems, cancer. May contain materials with toxic/carcinogenic effects. Small particles can become lodged in lungs.
Environmental effects: Reduces visibility; acid deposition of H2SO4 droplets can damage trees, soils, and aquatic life in lakes.
Property damage: Corrodes metal; soils and discolors buildings, clothes, fabrics, and paints
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Nitrogen Oxides
Nitrogen OxidesDescription: Reddish-brown irritating gas that gives photochemical smog its
brownish color; in the atmosphere can be converted to nitric acid (HNO3), a major component of acid deposition. Gases produced by the chemical interactions between atmospheric nitrogen and oxygen at high temperature
Major human sources: Fossil fuel burning in motor vehicles (49%) and power and industrial plants (49%).
Health effects: Lung irritation and damage; aggravates asthma and chronic bronchitis; increases susceptibility to respiratory infections such as the flu and common colds (especially in young children and older adults).
Environmental effects: Reduces visibility; acid deposition of HNO3 can damage trees, soils, and aquatic life in lakes.
Property damage: HNO3 can corrode metals and eat away stone on buildings, statues, and monuments; NO2 can damage fabrics.
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Sulfur Oxides
SULFUR DIOXIDE (SO2)
Description: Colorless, irritating; forms mostly from the combustion of sulfur containing fossil fuels such as coal and oil (S + O2 SO2); in the atmosphere can be converted to sulfuric acid (H2SO4), a major component of acid deposition. Gases produced by the chemical interactions between sulfur and oxygen.
Major human sources: Coal burning in power plants (88%) and industrial processes (10%). Causes acid precipitation
Health effects: Breathing problems for healthy people; restriction of airways in people with asthma; chronic exposure can cause a permanent condition similar to bronchitis. According to the WHO, at least 625 million people are exposed to unsafe levels of sulfur dioxide from fossil fuel burning.
Environmental effects: Reduces visibility; acid deposition of H2SO4 can damage trees, soils, and aquatic life in lakes.
Property damage: SO2 and H2SO4 can corrode metals and eat away stone on buildings, statues, and monuments; SO2 can damage paint, paper, and leather.
Gases produced by the chemical interactions between sulfur and oxygen
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Carbon Oxides and Hydrocarbons
Description: Colorless, odorless gas that is poisonous to air-breathing animals; forms during the incomplete combustion of carbon-containing fuels (2 C + O2 2 CO).
Major human sources: Cigarette smoking (p. 409), incomplete
burning of fossil fuels. About 77% (95% in cities)comes from motor vehicle exhaust.
Health effects: Reacts with hemoglobin in red blood cells and reduces the ability of blood to bring oxygen to body cells and tissues. This impairs perception and thinking; slows reflexes; causes headaches, drowsiness, dizziness, and nausea; can trigger heart attacks and angina; damages the development of fetuses and young children; and aggravates chronic bronchitis, emphysema, and anemia. At high levels it causes collapse, coma, irreversible brain cell damage, and death.
Carbon Oxides Gases carbon monoxide (CO) and carbon dioxide (CO2)
Greenhouse gases Hydrocarbons
Diverse group of organic compounds that contain only hydrogen and carbon (ex: CH4 - methane)
Some are related to photochemical smog and greenhouse gases
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Ozone
OZONE (O3)
Description: Highly reactive, irritating gas with an unpleasant odor that forms in the troposphere as a major component of photochemical smog
Major human sources: Chemical reaction with volatile organic compounds (VOCs, emitted mostly by cars and industries) and nitrogen oxides to form photochemical smog).
Health effects: Breathing problems; coughing; eye, nose, and throat irritation; aggravates chronic diseases such as asthma, bronchitis, emphysema, and heart disease; reduces resistance to colds and pneumonia; may speed up lung tissue aging.
Environmental effects: Ozone can damage plants and trees; smog can reduce visibility.
Property damage: Damages rubber, fabrics, and paints Troposphere Ozone
Man-made pollutant in the lower atmosphere Secondary air pollutant Component of photochemical smog
Stratospheric Ozone Essential component that screens out UV radiation in the upper atmosphere Man- made pollutants (ex: CFCs) can destroy it
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Ozone Damage to Grape Leaves
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Sources of Outdoor Air Pollution
Two main sources Transportation Industry
Intentional forest fires is also high
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Urban Air Pollution
Photochemical Smog (ex: Los Angeles below) Brownish-orange haze formed by chemical reactions involving
sunlight, nitrogen oxide, and hydrocarbons. Found in modern cities, especially in warm, sunny areas.
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Industrial smog (AKA London-type smog or gray smog)
Smoke pollution Worst is during the winter months when
combustion of household fuel is high. Serious problem in developing countries.
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Botkin and KellerEnvironmental Science 5e
Botkin and KellerEnvironmental Science 5e
Formation of Photochemical Smog
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Initial reaction of nitrogen dioxide with sunlight
sunlight2NO NO O
Urban Air Pollution
Atmospheric Inversion or aka temp. inversion: Occurs when warmer air is found above cooler air and it
poses a particular problem when there is a stagnant air mass.
Botkin and KellerEnvironmental Science 5e
Factors in smog formation
Precipitation Salty sea spray Wind Reduce factory/car
emissions
Urban buildings Hills and mountains High temperatures “Grasshopper Effect”
Decrease smog Increase smog
Sources of Smog in Los Angeles
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Effects of Air Pollution
Low level exposure Irritates eyes Causes inflammation of respiratory tract
Can develop into chronic respiratory diseases
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Children and Air Pollution
Greater health threat to children than adults Air pollution can restrict lung development Children breath more often than adults
Children who live in high ozone areas are more likely to develop asthma
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Controlling Air Pollution
Smokestacks with electrostatic precipitator (right) Electrode imparts
negative charge on the air pollutants
Negatively charged pollutants are then attracted to positively charged walls- fall into collector
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Controlling Air Pollution
Smokestacks with scrubbers (right)
Particulate material can also be controlled by proper excavating techniques
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Scrubbers
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Emissions not controlled- heavily polluted
Emissions controlled with scrubbers-only steam
expelled
Controlling Air Pollution
Phase I Vapor Recovery System for gasoline
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The Clean Air Act
Authorizes EPA to set limits on amount of specific air pollutants permitted
Focuses on 6 pollutants: lead, particulate matter, sulfur dioxide, carbon
monoxide, nitrogen oxides, and ozone Act has led to decreases in air pollutants
Most dramatic is lead - decreased by 98% since 1970 (due to switch to unleaded gasoline)
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The Clean Air Act
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Urban Air Quality
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Ozone Depletion in Stratosphere
Ozone Protects earth from UV radiation
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Ozone Depletion in Stratosphere
Ozone thinning/hole First identified in 1985
over Antarctica Occurs annually
between Sept and Nov because:
Caused by human-produced bromine and chlorine containing chemicals (Ex: CFCs)
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Ozone Depletion in Stratosphere
Hole over Antarctica requires two conditions: Sunlight just returning to polar region Circumpolar vortex- a mass of cold air that
circulates around the southern polar region Polar stratospheric clouds form
Enable chemical reactions that cause Cl and Br to destroy ozone
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Effects of Ozone Depletion
Higher levels of UV-radiation hitting the earth Eye cataracts Skin cancer (right) Weakened immunity
May disrupt ecosystems
May damage crops and forests
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Recovery of Ozone Layer
Montreal Protocol (1987) Reduction of CFCs Started using HCFCs (greenhouse gas)
Phase out of all ozone destroying chemicals is underway globally
Satellite pictures in 2000 indicated that ozone layer was recovering
Full recovery will not occur until 2050
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Acid Deposition (AKA Acid Rain) Sulfur dioxide and nitrogen dioxide emissions
react with water vapor in the atmosphere and form acids that return to the surface as either dry or wet deposition
pH scale
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Chemistry and Acid Rain
The pH of rainwater is normally slightly acidic, at about 5.6, due mainly to reaction of carbon dioxide with water to form carbonic acid.
2 2 2 3CO H O H CO
Gases from natural events
Volcanic eruptions, forest fires, and lightning produce sulfur dioxide, sulfur trioxide, and nitrogen dioxide.
These gases can react with atmospheric water in much the same way that carbon dioxide does to produce sulfurous acid, sulfuric acid, nitric acid and nitrous acid.
Refer to “Chemistry is indeed relevant to APES.”
2 2 2 3
3 2 2 4
2 2 3 22
SO H O H SO
SO H O H SO
NO H O HNO HNO
How Acid Deposition Develops
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Effects of Acid Deposition
Declining Aquatic Animal Populations
Thin-shelled eggs prevent bird reproduction Calcium is unavailable
in acidic soil Forest decline
(right) Black Forest in Germany
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Acid Deposition and Forest Decline
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pH levels of US soil
Air Pollution Around the World
Air quality is deteriorating rapidly in developing countries Developing countries have older cars
Shenyang, China Residents only see sunlight a few weeks each
year 5 worst cities in world
Beijing, China; Mexico City, Mexico; Shanghai, China; Tehran, Iran; and Calcutta, India
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Case-In-Point Air Pollution in Beijing and Mexico City
Beijing (left) Mexico City (right)
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Long Distance Transport of Air Pollutants
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Global Distillation
Effect
Reduce air pollution by improving energy efficiency
Reduce coal use
Increase natural gas use
Increase use of renewable resources
Burn low-sulfur coal
Remove SO2 particulates, and Nox from smokestack gases
Remove Nox from motor vehicular exhaust
Tax emissions of SO2
Add lime to neutralizeacidified lakes
Add phosphatefertilizer to neutralizeacidified lakes
Acid Rain Prevention and Solution
Solutions
Acid Deposition
Prevention Cleanup
Indoor Air Pollution
Pollutants can be 5–100x greater than outdoors
Radon, cigarette smoke, carbon monoxide, nitrogen dioxide, formaldehyde pesticides, lead, cleaning solvents, ozone, and asbestos
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Formaldehyde
Found in: plywood, furniture, upholstery, floor adhesives, dry cleaning chemicals.Causes: breathing problems, headache, sore throat, dizziness, eye irritation in those sensitive to low levels.Chronic exposure to higher levels can lead to cancer.
Radon• Naturally occurring from radioactive decay of U-238.• Occurs in soils, bedrock and can get into homes through cracks.• Can’t get out and builds up• Can lead to lung cancer
Chloroform: chlorine-treated hot water; cancers
Para-dichlorobenzene: air fresheners, moth balls;
cancersTetrachloroethylene: dry cleaning residue; nerve, liver,
kidney problems
Formaldehyde: from processed
wood; eye, nose, throat, lung irritant
Benzo--pyrene: from smoke; lung
cancer
Styrene: from carpet/plastic. Kidney/liver problems
Radon-222: from soils, lung disease
Methylene Chloride: paint stripper, thinner;
nerve, diabetes
Tobacco Smoke
Carbon Monoxide
Asbestos: old floor tile,Pipe insulation;
lung problems, cancer
Nitrogen Oxides:Gas ovens, kerosene
heaters, un-vented gas burning; lung irritation,
headaches
1, 1, 1-Trichloroethane: aerosals; dizziness, irregular breathing
Indoor Air Pollution - Radon
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VI. Pollution (25-30%)
Air pollution
1. Sources-primary and secondary
2. major air pollutants (pollutant chart)
3. measurement units
4. smog
5. acid deposition-causes and effects
6. indoor air pollution
7. remediation and reduction strategies trading article, emissions trading game)
8. Clean Air Act and other relevant laws