Chapter 20: air pollution

Pollution unit

20.1 Layers of the Atmosphere

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

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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

Pressure

Highlights:

Pressure decreases with altitude until it reaches zero

Troposphere is the layer we live in; mostly N and O; weather; colder as you go up

Stratosphere: has the ozone layer; warmer as you go up

Environmental science focuses mostly on those two layers

What SPF is that ozone?

• Stratospheric ozone absorbs 95% of UV radiation

• 3O2 + UV 2 O3

• Tropospheric ozone is harmful to plants, animals, and humans.

• Tropospheric ozone is made when air pollutants undergo chemical reactions because of UV exposure.

Which ozone is which?

• The oxygen atom generated from the initial reaction reacts with atmospheric, diatomic oxygen, to form ozone.

• This polluting ozone of the lithosphere, traps heat and contributes to thermal inversion.

2 3O O O

20.2 Outdoor Air Pollution

.

Primary & SecondaryPollutants

Play intro video

Primary Pollutants

Secondary Pollutants

Sources NaturalStationary

CO CO2

SO2 NO NO2

Most hydrocarbons

Most suspendedparticles

SO3

HNO3 H2SO4

H2O2 O3 PANs

Most and saltsNO3–

Mobile

SO42 –

Primary vs. Secondary

Tip – Can’t remember what organic compounds are???

View my PS (Chapter 9) PPT online for a quick refresher.

Table 20-1Page 436

Major classes of air pollutants

Class

Carbon oxides

Sulfur oxides

Nitrogen oxides

Volatile organic compounds (VOCs)

Suspended particulate matter (SPM)

Photochemical oxidants

Radioactive substances

Hazardous air pollutants (HAPs), which cause health effects such as cancer, birth defects, and nervous system problems

Examples

Carbon monoxide (CO) and carbon dioxide (CO2)

Sulfur dioxide (SO2) and sulfur trioxide (SO3)

Nitric oxide (NO), nitrogen dioxide (NO2), nitrous oxide (N2O) (NO and NO2 often are lumped together and labeled NOx)

Methane (CH4), propane (C3H8), chlorofluorocarbons (CFCs)

Solid particles (dust, soot, asbestos, lead, nitrate, and sulfate salts), liquid droplets (sulfuric acid, PCBs, dioxins, and pesticides)

Ozone (O3), peroxyacyl nitrates (PANs), hydrogen peroxide(H2O2), aldehydes

Radon-222, iodine-131, strontium-90, plutonium-239 (Table 3-1, p. 49)

Carbon tetrachloride (CCl4), methyl chloride (CH3Cl), chloroform (CHCl3), benzene (C6H6), ethylene dibromide (C2H2Br2), formaldehyde (CH2O2)

CARBON MONOXIDE (CO)

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), incompleteburning 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 Monoxide

Table 20-2 Major Outdoor Air Pollutants

Table 20-2Page 438

Table 20-2 Major Outdoor Air Pollutants

NITROGEN DIOXIDE (NO2)

Description: 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.

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 theflu 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.

Nitrogen Dioxide

Table 20-2Page 438

Table 20-2 Major Outdoor Air Pollutants

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 atmospherecan be converted to sulfuric acid (H2SO4), a major component of acid deposition.

Major human sources: Coal burning in power plants (88%) and industrial processes(10%).

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.

Sulfur Dioxide

Table 20-2Page 438

Table 20-2 Major Outdoor Air Pollutants

SUSPENDED PARTICULATE MATTER (SPM)

Description: Variety of particles and droplets (aerosols) small and light enough to remain suspended in atmosphere for short periods (large particles) to long periods(small particles; Figure 20-6, p. 441); cause smoke, dust, and haze.

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.

Environmental effects: Reduces visibility; acid deposition of H2SO4 droplets candamage trees, soils, and aquatic life in lakes.

Property damage: Corrodes metal; soils and discolors buildings, clothes, fabrics, and paints.

Suspended Particulate Matter

Table 20-2Page 438

Table 20-2 Major Outdoor Air Pollutants

LEAD

Description: Solid toxic metal and its compounds, emitted into the atmosphere as particulate matter.

Major human sources: Paint (old houses), smelters (metal refineries), lead manufacture, storage batteries, leaded gasoline (being phased out in developed countries).

Health effects: Accumulates in the body; brain and other nervous system damage and mental retardation (especially in children); digestive and other health problems; some lead-containing chemicals cause cancer in test animals.

Environmental effects: Can harm wildlife.

Lead

Table 20-2Page 438

Table 20-2 Major Outdoor Air Pollutants

OZONE (O3)

Description: Highly reactive, irritating gas with an unpleasant odor that forms in the troposphere as a major component of photochemical smog (Figures 20-3 and 20-5).

Major human sources: Chemical reaction with volatile organic compounds (VOCs, emitted mostly by cars and industries) and nitrogen oxides to form photochemical smog (Figure 20-5).

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.

Ozone

20.3 Photochemical and Industrial Smog

Smog

• Photochemical: “brown air smog” Caused by UV reacting with chemicals (NOx, VOCs in the atmosphere) Found in modern cities, especially in warm, sunny areas.

• Industrial smog: “gray air smog” Caused by burning of fossil fuels, adds sulfur to air. Rare in developed countries now as soot is removed by filters..

Photochemical Smog• Nitrogen oxide is an essential ingredient of

photochemical smog that is produced during the high temperatures associated with combustion of vehicle’s engines.

• Be sure to look at sheet “Chemistry is indeed relevant to APES.”

2 2 2N O Energy NO

Initial reaction of nitrogen dioxide with sunlight

sunlight2NO NO O

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

“Grasshopper Effect”

• This is one reason why the dangerous chemicals Canada banned more than 20 years ago continue to turn up in the Great Lakes.

View “Chemistry is indeed relevant to APES.”

• See equation – reactants and products of photochemical smog on sheet.

• Hydrocarbons (including VOC’s), carbon monoxide, and nitrogen oxides from vehicle exhausts are irradiated by sunlight in the presence of oxygen gas.

• The resulting reactions produce a potentially dangerous mixture that include other NOx, ozone, and irritating organic compounds (VOC’s), as well as CO2 and H2O vapor

That’s just smoke out your…….

20.4 Regional Outdoor Air Pollution from Acid Deposition

Acid Rain

Play intro video

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.

Refer to “Chemistry is indeed relevant to APES.”

•

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

Wind

Transformation tosulfuric acid (H2SO4)and nitric acid (HNO3)

Nitric oxide (NO)

Acid fog

Ocean

Sulfur dioxide (SO2)and NO

Windborne ammonia gasand particles of cultivated soilpartially neutralize acids andform dry sulfate and nitrate salts

Dry aciddeposition(sulfur dioxidegas and particlesof sulfate andnitrate salts)

Farm

Lakes indeep soilhigh in limestoneare buffered

Lakes in shallowsoil low inlimestonebecomeacidic

Wet acid deposition(droplets of H2SO4 andHNO3 dissolved in rainand snow)

Acid Rain formation

Wind

Ocean

Farm

Which location does sulfuric & nitric acids transform?

Y

Z

X

Wind

Ocean

Farm

Identify the type of acid deposition at point Y

Y

Z

Transformation tosulfuric acid (H2SO4)and nitric acid (HNO3)

Wind

Ocean

Farm

Identify the type of acid deposition at point Z

X

Z

Dry aciddeposition

Wind

Ocean

Farm

Great Job!!

X

Y

Wet acid deposition

Primary Pollutants

Secondary Pollutants

Sources NaturalStationary

CO CO2

SO2 NO NO2

Most hydrocarbons

Most suspendedparticles

SO3

HNO3 H2SO4

H2O2 O3 PANs

Most and saltsNO3–

Mobile

SO42 –

Which chemicals lower the pH of rain?

Primary Pollutants

Secondary Pollutants

Sources NaturalStationary

CO CO2

SO2 NO NO2

Most hydrocarbons

Most suspendedparticles

SO3

HNO3 H2SO4

H2O2 O3 PANs

Most and saltsNO3–

Mobile

SO42 –

Secondary Pollutants in RED

pH levels of US soil

Effects of Acid Rain

• Decrease soil pH (more acidic)

• Decrease pH of rivers, lakes, ponds, etc

• Fish kills

• Lung/respiratory problems

• Degrade metal pipes, leading to water pollution

• Plants become susceptible to disease, parasites, etc

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

20.5 Indoor Air Pollution

Go outside and play• Indoor air is typically a greater threat

• People are inside up to 98% of their time

• Less air flow to remove pollutants

• Top pollutants: cigarette smoke, formaldehyde, radon, particulate matter.

• “Sick building” Typically newer buildings because of less air leaks. Symptoms: headache, coughing, sneezing, tiredness.

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

Solutions

Indoor Air Pollution

Prevention Cleanup

Cover ceiling tiles and lining of AC ducts to prevent release of mineral fibers

Ban smoking or limit it to well-ventilated areas

Set stricter formaldehyde emissions standards for carpet, furniture, and building materials

Prevent radon infiltration

Use office machines in well-ventilated areas

Use less polluting substitutes for harmful cleaning agents, paints, and other products

Use adjustable fresh air vents for work spaces

Increase intake of outside air

Change air more frequently

Circulate building’s air through rooftop greenhouses

Use exhaust hoods for stoves and appliances burning natural gas

Install efficient chimneys for wood-burning stoves

Particulates - Aka: particulate matter (PM)

• What are they? aerosols or fine particles, are tiny particles of solid (a smoke) or liquid (an aerosol) suspended in a gas.

• Size: < 10 nm - > 100 µm in diameter.

• Who do they effect? Sensitive populations such as children, the elderly, and individuals suffering from respiratory disease.

Particulate Matter (PM)

• Larger particles are generally filtered in the nose and throat and do not cause problems.

• PM smaller than about 10 µm, referred to as PM10, can settle in the bronchi and lungs and cause health problems.

Particulate Matter (PM)

• Includes a wide range of pollutants – – road dust– diesel soot– fly ash– wood smoke– sulfate aerosols (suspended as particles in

the air) These particles are a mixture of visible and

microscopic solid particles and minute liquid droplets known as aerosols.

Take a deep breath…• Asthma: on the rise! WHY?? • Varying opinions:

• Overly sterile environment as children; don’t build up natural immunity

• Exposure to allergens• Genetic make up• Exposure to pollution

• Lung cancer• Chronic bronchitis• Emphysema

National Ambient Air Quality Standards (NAAQS)

Standards established by the EPA that apply for outdoor air throughout the country.

Primary standards are designed to protect human health.

Secondary standards are designed to protect public welfare (e.g. building facades, visibility, crops, and domestic animals).

EPA’s watchful eye

NAAQS requires the EPA to set standards on six criteria pollutants:

1.Ozone (O3) 2.Particulate Matter3.Carbon monoxide (CO)

4.Sulfur dioxide (SO2)

5.Nitrogen oxides (NOx) 6.Lead (Pb)

Temperature Inversions (pg. 442)

andHeat Islands (online activity)

Warmer air

Inversion layer

Cool layer

MountainMountain

Valley

Decreasing temperature

Incr

easi

ng

alt

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Temperature Inversion

Traps pollutants near surface. Mountains prevent wind in area and shadow sun to keep lower air cool.

Inversion layer

Mountainrange

Sea breeze

Descending warm air mass

Decreasing temperature

Incr

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ng

alt

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Temperature Inversion

Traps pollutants near surface. Mountains prevent pollutants leaving. Sea breeze blows in, not out This is what is happening in LA. Video clip

20.7 Preventing and Reducing Air Pollution

Solutions

Stationery Source Air Pollution

Prevention Dispersion or Cleanup

Burn low-sulfurcoal

Remove sulfurfrom coal

Convert coalto a liquid orgaseous fuel

Shift to lesspolluting fuels

Disperseemissions abovethermal inversionlayer with tallsmokestacks

Removepollutants aftercombustion

Tax each unitof pollutionproduced

Out-put or Control Methods

See text pg. 457 Fig 20-18

Electrostatic Precipitator – static plates collect particles

Dirty gas

Dust discharge

Electrodes

Cleaned gas

Cleaned gas

Dirty gas

Baghouse Filter – only one to remove hazardous fine particles

Dust discharge

Bags

Dirty gas

Dirty water

Cleanwater

Wet Scrubber – Expensive

Wetgas

Cleaned gas

Remove 98% of SO2 and PM from emissions

Cyclone Separator - Cheap

Dirty gas

Dust discharge

Cleaned gas

Does NOT produce hazardous materials like other

Solutions

Motor Vehicle Pollutions

Prevention Cleanup

Mass transit

Bicycles and walking

Less polluting engines

Less polluting fuels

Improve fuel efficiency

Get older, pollutingcars off the road

Give buyers tax write-offs for buying low-polluting, energy-efficient vehicles

Restrict driving inpolluted areas

Emission controldevices

Car exhaustInspectionstwice a year

Stricter emissionstandards

Solutions for mobile

emissions

Solutions

Air Pollution

Prevention Cleanup

Improve energy efficiencyto reduce fossil fuel use

Rely more on lower-polluting natural gas

Rely more on renewable energy (especially solar cells, wind, and solar-produced hydrogen)

Transfer technologies for latest energy efficiency, renewable energy, and pollution prevention to developing countries.

Reduce poverty

Distribute cheap and efficient cookstoves to poor families in developing countries

Reduce or ban indoor smoking

Develop simple and cheap test for indoor pollutants such as particulates, radon, and formaldehyde

Clean Air Acts

• US Congress in 1970, 1977, 1990

• EPA regulation of emissions that contribute to global warming, ozone depletion and air pollution. View clip

• You should read ALL case studies in the chapter!

• Ea: The Bad Old Days, A Burning Controversy and section 20-7 specifically.

VI. Pollution (25-30%)

Air pollution1. Sources-primary and secondary (20.2 & air pollution lab)

2. major air pollutants (20.2 & pollutant chart)

3. measurement units (air pollution lab & emissions trading game)

4. smog (20.3 & Demo: Smog in a jar)

5. acid deposition-causes and effects (20.4, pH/acid rain lab, video)

6. heat islands (online activity) and temperature inversions (20.3)

7. indoor air pollution (20.5 &  air particulate lab)

8. remediation and reduction strategies (air pollution allowance trading article, emissions trading game) and Fig. 20-18)

9. Clean Air Act and other relevant laws (Law sheet, NAAQS)