19 Air Pollution. Overview of Chapter 19 Atmosphere as a Resource Types and Sources of Air Pollution Effects of Air Pollution Controlling Air

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

© 2012 John Wiley & Sons, Inc. All rights reserved.

Atmospheric pressure (millibars)0 200 400 600 800 1,000

120

110

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90

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70

60

50

40

30

20

10

0(Sea

Level)–80 –40 0 40 80 120

Pressure = 1,000millibars atground levelTemperature (˚C)

Alt

itu

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(kilo

met

ers)

Alt

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(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


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


Major Air Pollutants



Major Classes of Air Pollutants

Particulate Material Nitrogen Oxides Sulfur Oxides Carbon Oxides Hydrocarbons Ozone


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


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.


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


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


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


Ozone Damage to Grape Leaves


Sources of Outdoor Air Pollution

Two main sources Transportation Industry

Intentional forest fires is also high


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.


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.


Botkin and KellerEnvironmental Science 5e


Formation of Photochemical Smog


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.


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


Effects of Air Pollution

Low level exposure Irritates eyes Causes inflammation of respiratory tract

Can develop into chronic respiratory diseases


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


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



Smokestacks with scrubbers (right)

Particulate material can also be controlled by proper excavating techniques


Scrubbers


Emissions not controlled- heavily polluted

Emissions controlled with scrubbers-only steam

expelled


Phase I Vapor Recovery System for gasoline


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)


The Clean Air Act


Urban Air Quality


Ozone Depletion in Stratosphere

Ozone Protects earth from UV radiation



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)



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


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


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


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


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


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


Acid Deposition and Forest Decline


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


Case-In-Point Air Pollution in Beijing and Mexico City

Beijing (left) Mexico City (right)


Long Distance Transport of Air Pollutants


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


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


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

Documents

19 Air Pollution. Overview of Chapter 19 Atmosphere as a Resource Types and Sources of Air Pollution Effects of Air Pollution Controlling Air