Air Pollution Chapter 18 Core Case Study: South Asias Massive Brown Cloud Asian Brown Cloud Causes...

transcript

Air Pollution

Chapter 18

Core Case Study: South Asia’s Massive Brown Cloud

Asian Brown Cloud• Causes

• clearing and burning forest for planting crops• Burning of coal, diesel, and other fossil fuels in industries , vehicles

and homes

• Chemical composition• 1/3rd of it is dust, smoke, and ash• Rest is acidic compounds, soot, toxic metals (mercury and lead),

hundreds of organic compounds and fly ash

• Areas impacted• much of India, Bangladesh, the industrial heart of China, the Open

Sea east of this area• Photosynthesis has been reduced by 7-10%• Acid in the haze fall to the surface and damage crops, trees, and

aquatic life

The Asian Brown Cloud

Air pollution connects the worldOn certain days

25% of particulate matter77% of black carbon33% of toxic mercury in the skies above LA can be traced to China

Steps taken in China and India to reduce air pollution

• strict pollution controls standards for coal-burning industries

• shifting from coal to cleaner burning natural gas

Air Pollution in Shanghai, China, in 2004

18-1 The Atmosphere Consists of Several Layers

Atmosphere varies in• Density

• The air we breathe at sea level is denser than the air on top of the world’s highest mountains.

• Atmospheric pressure• Decreases with altitude because they are fewer gas

molecules at higher levels

Earth’s AtmosphereEarth’s Atmosphere

Compared to the size of the Earth (12000 km)

The atmosphere is very thin (120 km)or

(75 miles)

http://www.gsfc.nasa.gov/gsfc/earth/pinatuboimages.htm

After Mt. Pinatubo eruption 1991

Atmospheric Layers

The atmosphere consists

of layers around the Earth,

each one defined by the

way temperature changes

within its limits.

The layer boundaries are:Tropopause

Stratopause

Mesopause

The outermost, the

thermosphere, thins

slowly, fading into space

with no boundary.

TroposphereAir mixes vertically andhorizontally. All weatheroccurs in this layer.

StratosphereTemperature is stable to20 km, then increases due to absorption of UV by the thin layer of ozone.

MesosphereTemperature is constant in the lower mesosphere, but decreases steadily with height above 56 km.

ThermosphereThis layer extends as high as 1000 km. Temperature increases rapidly after about 88 km.

Aurora, caused by collisions between protons and electrons from the Sun and oxygen and nitrogen atoms in the atmosphere.

Meteor burning up

Air Movements in the Troposphere Play a Key Role in Earth’s Weather and Climate

Troposphere • This is where we live

• 8 to 14.5 kilometers high (5 to 9 miles)• the temperature drops from about 17 to -52 degrees

Celsius• 75–80% of the earth’s air mass• most dense• Closet to the earth's surface• Rising and falling air currents: weather and climate• Involved in chemical cycling

Composition

Nitrogen (N2, 78%) Oxygen (O2, 21%) Argon (Ar, 1%) myriad of other very influential

components are also present which include the Water (H2O, 0 - 7%), "greenhouse" gases or Ozone (O3, 0 - 0.01%), Carbon Dioxide (CO2, 0.01-0.1%),

The Stratosphere Is Our Global Sunscreen

Stratosphere• extends to 50 kilometers (31 miles) high• dry and less dense• temperature in this region increases gradually to -3

degrees Celsius, due to the absorption of ultraviolet radiation

• ozone layer absorbs and scatters the solar ultraviolet radiation

• ninety-nine percent of "air" is located in first two layers• every 1000-m 11% less air pressure

• Similar composition to the troposphere, with 2 exceptions• Much less water

• O3, ozone layer, filters UV

Natural Capital: The Earth’s Atmosphere Is a Dynamic System with Four Layers

O3 -The Good, the Bad, and the Ugly

O3 -The Good

(15 - 40 km) blocks solar UV<290 nm

Beneficial Ozone that forms in the stratosphere protects life on earth by filtering out most of the incoming harmful UV radiation emitted by the sun

O3 -The Bad6-10 km : greenhouse gas absorbs IR emitted by Earth

O3 →O3 (v=1) Harmful or Photochemical ozone forms in the troposphere when various air pollutants undergo chemical reactions under the influence of sunlight. Ozone in the atmosphere near the earth’s surface damages plants, lung tissue, and some materials such as rubber. It is a strong oxidant and respiratory irritant.Ground level ozone results primarily from motor-vehicle exhaust

O3 -The Ugly

part of smog (bad, too)

18-2 Air Pollution Comes from Natural and Human Sources

Air pollution • The presence of chemicals in the atmosphere

in concentrations high enough to harm organisms, ecosystems, or human-made material.

Natural sources• Dust blown by wind• Pollutants from wildfires and volcanoes• Volatile organics released by plants • Withdrawing groundwater

Air Pollution Comes from Natural and Human Sources

Human sources: mostly in industrialized and/or urban areas• Stationary sources• Mobile sources

Sources and Types of Air Pollutants

Fig. 18-4, p. 472

Primary Pollutants

CO CO2Secondary Pollutants

SO2 NO NO2

Most hydrocarbons SO3

Most suspended particles HNO3 H2SO4

H2O2 O3 PANs

Sources Natural Stationary

Mobile

Most NO3− and SO4

2− salts

Case Study: Air Pollution in the Past: The Bad Old Days

Discovery of fire Middle Ages 1700’s - Industrial Revolution London, England• 1850s dense mixture of coal smoke and fog

• 1880- a prolonged coal fog killed an estimated 2,200 people

• 1952: yellow fog lasted for 5 days and killed 4,000- 12,000 Londoners

• Clean Air Act of 1956

Case Study: Air Pollution in the Past: The Bad Old Days (2)

United States • 1948: Donora, PA; first U.S. air pollution disaster• 1963: New York City

Global problem• Urban areas in China, India and parts of Eastern

Europe that depend on coal in industries and in some homes face air pollution levels similar to those in London and America in the 1950’s

Some Pollutants in the Atmosphere Combine to Form Other Pollutants

Primary pollutants• Are harmful chemicals emitted directly into the air from

natural processes and human activities.

Secondary pollutants• Primary pollutants react with one another and with the basic

components of air to form new harmful chemicals

Air quality improving in developed countries Much more needs to be done in developing

countries• Indoor pollution: big threat to the poor

Indoor Air Pollution

What Are the Major Outdoor Air Pollutants?

Carbon oxides • Carbon monoxide (CO)

• Colorless and highly toxic that forms during the incomplete combustion of carbon-containing materials. Reacts with hemoglobin in blood cells reduces the ability to transport oxygen.

• Sources • Motor vehicles exhaust, burning of forest and grasslands,

tobacco smoke, and open fires and inefficient stoves used for cooking.

• Carbon dioxide (CO2) • Colorless, odorless gas. • 93% result of natural carbon cycle

• Rest from burning fossil fuels and clearing CO2 absorbing forest and grasslands.

• Emissions have been rising since the industrial revolution

Nitrogen oxides (NO) and nitric acid (HNO3)

• Sources- automobiles, coal-burning plants• NO reacts with oxygen to form NO2 (reddish brown gas) NO and

NO2 are collectively called NOx

• Acid deposition• Photochemical smog• Human health and environmental impact • Nitrous oxide (N2O) a greenhouse gas that is

emitted from fertilizers and animal waste and by burning fossil fuels

Major Outdoor Pollutants

Sulfur dioxide (SO2) and sulfuric acid (H2SO4) 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.

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.

Particulates• Suspended particulate matter (SPM)• Variety of particles and droplets (aerosols) small and light enough to remain

suspended in atmosphere for short periods (large particles) to long periods

cause smoke, dust, and haze.

• 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.

• Human health and environmental impact• 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.

• Reduces visibility; acid deposition of H2SO4 droplets can

damage trees, soils, and aquatic life in lakes

Ozone (O3)• Highly reactive, irritating gas with an unpleasant odor that forms

in the troposphere as a major component of photochemical smog

• Sources Chemical reaction with volatile organic compounds (VOCs, emitted mostly by cars and industries) and nitrogen oxides to form photochemical smog

• Human and environmental impact• 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.

Volatile organic compounds (VOCs)• organic compounds (hydrocarbons) that evaporate easily,

usually aromatic

• Hydrocarbons and terpenes• Sources

• Methane, chlorofluorocarbon, benzene and proprane.• vehicles (largest source), evaporation of solvents or fossil

fuels, aerosols, paint thinners, dry cleaning

• Human and environmental impact• eye and respiratory irritants; carcinogenic; liver, CNS, or

kidney damage; damages plants; lowered visibility due to brown haze; global warming

Chemical Reactions That Form Major Outdoor Air Pollutants

Statue Corroded by Acid Deposition and Other Forms of Air Pollution, RI, U.S.

Natural Capital: Lichen Species, Vulnerability to Air Pollutants

Case Study: When is a Lichen Like a Canary

Case Study: Lead Is a Highly Toxic Pollutant

Does not break down in the environment Solid toxic metal and its compounds, emitted

into the atmosphere as particulate matter. Sources

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

Human health and environmental impact• 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. Can harm wildlife.

Case Study: Lead Is a Highly Toxic Pollutant

Reduction of lead (Pb)• Unleaded gasoline• Unleaded paint 1960

Still problems• 2007: toys with Pb paint recalled• 2007 2/3rd of red long-lasting lipstick

manufactured in the US contained surprisingly high levels of lead.

• Global ban on lead in gasoline and paint

Fig. 18-7, p. 476

SOLUTIONSLead Poisoning

Prevention ControlPhase out leaded gasoline worldwide

Replace lead pipes and plumbing fixtures containing lead solder

Phase out waste incineration

Remove leaded paint and lead dust from older houses and apartments

Ban use of lead solder

Sharply reduce lead emissions from incinerators

Ban use of lead in computer and TV monitors

Remove lead from TV sets and computer monitors before incineration or land disposal

Ban lead glazing for ceramicware used to serve food

Test for lead in existing ceramicware used to serve food

Ban candles with lead cores

Test existing candles for lead

Test blood for lead by age 1

Wash fresh fruits and vegetables

Burning Coal Produces Industrial Smog

Chemical composition of industrial smog • mixture of SO2, droplets of sulfuric acid, and a variety of

suspended solid particles emitted by burning coal

Reduction of this smog in urban cities of the United States

China and smog

How Pollutants Are Formed from Burning Coal and Oil, Leading to Industrial Smog

Fig. 18-8, p. 476

Ammonium sulfate [(NH4)2SO4]

Ammonia (NH3)

Sulfuric acid (H2SO4)

Carbon monoxide (CO) and

carbon dioxide (CO2)

Water vapor (H2O)

Sulfur trioxide (SO 3 )

Oxygen (O2)

Sulfur dioxide (SO2)

Burning coal and oil

Oxygen (O2)

Sulfur (S) in coal and oil

Carbon (C) in coal and oil

Fig. 18-8, p. 476

Burning coal and oil

Oxygen (O2)

Stepped Art

Ammonium sulfate [(NH4)2SO4]

Ammonia (NH3)

Sulfuric acid (H2SO4)

Water vapor (H2O)

Sulfur trioxide (SO 3 )

Oxygen (O2)

Sulfur dioxide (SO2)

Sulfur (S) in coal and oil

Carbon monoxide (CO) and

carbon dioxide (CO2)

Carbon (C) in coal and oil

Sunlight Plus Cars Equals Photochemical Smog

Photochemical Smog• Chemical composition

• is a mixture of air pollutants formed by the reaction of nitrogen oxides and volatile organic hydrocarbon compounds under the influence of light

VOCs + NO2 + Heat + Sunlight yields

• Ground level O3 and other photochemical oxidants

• Aldehydes• Other secondary pollutants

A Model of How Pollutants That Make Up Photochemicals Are Formed

Fig. 18-9, p. 477

PANS and other pollutantsVolatile organic compounds (VOCs)

Ozone (O3)

Oxygen (O2)

Nitric oxide (NO) +

Oxygen atom (O)

Water vapor (H2O)Hydrocarbons UV radiation

Peroxyacyl nitrates (PANs)

Nitrogen dioxide (NO2)

Oxygen (O2)

Nitric oxide (NO)

Oxygen (O2)

Nitrogen (N) in fossil fuel

Burning fossil fuels

Global Outlook: Photochemical Smog in Santiago, Chile

How can trees Contribute to Photochemical Smog?

Trees certainly have environmental benefits• Emit oxygen, absorb CO2, provide shade, and help

absorb and remove various pollutants from the air. Some trees (some oak species, sweet gums,

Poplars, and Kudzu) in and around urban areas play a large role in smog formation• They emit VOCs (like isoprene) that are ingredients

in the development of photochemical smog. • Plants in urban areas should be trees that emit low

levels of VOCs.

Several Factors Can Decrease or Increase Outdoor Air Pollution

Outdoor air pollution may be decreased by• Settling of particles due to gravity• Rain and snow• Salty sea spray from the ocean• Winds • Chemical reactions

Several Factors Can Decrease or Increase Outdoor Air Pollution

Outdoor air pollution may be increased by• Urban buildings• Hills and mountains• High temperatures• Emissions of VOCs from certain trees and plants • Grasshopper effect• Temperature inversions

A Temperature Inversion

Fig. 18-11, p. 478

Warmer air Descending warm air mass

Inversion layer Inversion layer

Sea breezeIncreasing altitude

Decreasing temperature

Animation: Formation of photochemical smog

Animation: Thermal inversion and smog

18-3 Acid Disposition Is a Serious Regional Air Pollution Problem

Acid deposition, acid rain• Local versus regional problems• Tall smokestacks reduce local air pollution by

increases region air pollution downwind• Effects of prevailing winds

• Where is the worst acid deposition?

When gas pollutants e.g. carbon dioxide, sulfur dioxide, nitrogen dioxide dissolve in rain water,

various acids are formed.

CO2 + H2O H2CO3 (carbonic acid)SO2 + H2O H2SO3 (sulfurous acid)NO2 + H2O HNO2 (nitrous acid) +

HNO3 (nitric acid)

Acid Deposition Formation

Causes of Acid Rain

Sulfur dioxide (SO2) and nitrogen oxides (NOx)

are the primary causes of acid rain.

In the US, About 2/3 of all SO2and 1/4 of all NOx comes from electric power

generation that relies on burning fossil fuels like coal.

Natural Capital Degradation: Acid Deposition, Acid Rain

pH measurements in relation to major coal-burning andindustrial plants. (Normal rain has a pH of 5.6)

Current and Possible Future Acid Rain Problem Areas

Fig. 18-13, p. 480

Potential problem areas because of sensitive soils

Potential problem areas because of air pollution: emissions leading to acid deposition

Current problem areas (including lakes and rivers)

Increased Acidity

• Dry deposited gases and particles can also be washed from trees and other surfaces by rainstorms.

• The runoff water adds those acids to the acid rain, making the combination more acidic than the falling rain alone.

Effects of Acid Rain• Has a variety of effects, including damage to

forests and soils, fish and other living things, materials, and human health.

• Also reduces how far and how clearly we can see through the air, an effect called visibility reduction.

• Effects of acid rain are most clearly seen in the aquatic environments

• Most lakes and streams have a pH between 6 and 8

http://cica.indiana.edu/projects/Biology/movies.html

Buffering Capacity• Acid rain primarily affects sensitive

bodies of water, which are located in watersheds whose soils have a limited “buffering capacity”

• Lakes and streams become acidic when the water itself and its surrounding soil cannot buffer the acid rain enough to neutralize it.

• In areas where buffering capacity is low, acid rain also releases aluminum ions from soils into lakes and streams; aluminum is highly toxic to many species of aquatic organisms referred to as acid shock.

http://home.earthlink.net/~photofish/fish_photos/sw10_thumb.jpg

Effects on Wildlife• Generally, the young of most species

are more sensitive to environmental conditions than adults.

• At pH 5, most fish eggs cannot hatch.

• At lower pH levels, some adult fish die.

• Some acid lakes have no fish.

Acid Rain and Forests

• Acid rain does not usually kill trees directly.

• Instead, it is more likely to weaken trees by damaging their leaves, limiting the nutrients available to them, or exposing them to toxic substances slowly released from the soil.

GermanyGermanyMongoliaMongolia

Effects of Acid Rain

Great Smoky Mountains, NC

Nutrients• Acidic water dissolves the nutrients and

helpful minerals in the soil and then washes them away before trees and other plants can use them to grow.

• Acid rain also causes the release of substances that are toxic to trees and plants, such as aluminum, into the soil.

Acid Deposition Has a Number of Harmful Effects

Human respiratory disorders

Aquatic ecosystems affected

Release of toxic metal• Toxic lead and mercury

Leaching of soil nutrients

Loss of crops and trees

Damage to buildings, statues, and monuments

Natural Capital Degradation: Air Pollution Damage to Trees in North Carolina, U.S.

Solutions: Acid Deposition, Prevention and Cleanup

Active Figure: Acid deposition

Video: Air pollution in China

Active Figure: Effect of air pollution in forests

18-4 Indoor Air Pollution Is a Serious Problem

Developing countries• Indoor burning of wood, charcoal, dung, crop

residues, coal in open fires or unvented or poorly vented stoves

• Poor suffer the greatest risk

Developed countries• Indoor air pollution is greater than outdoor air

pollution

Exposure

Time spent in various environments in US and less-developed countries

Indoor Air Pollution Is a Serious Problem

Why?• 11 of the common air pollutants higher inside

than outside• Greater in vehicles than outside• Health risks magnified: people spend 70–98% of

their time is indoors

Who are at greatest risk from indoor air pollution?• Children under 5 and the elderly• Sick• Pregnant women• People with respiratory disorders or heart

problems• Smokers• Factory workers

Four most dangerous indoor air pollutants• Tobacco smoke- most preventable • Formaldehyde

• Found in many building material, and household products (plywood, particle board, paneling, high-gloss wood, drapes, furniture, carpets, wallpaper, wrinkle- free coating on permanent –press clothing)

• The chemical that causes most people in developed countries difficulty

• Colorless extremely irritating chemical• Causes chronic breathing problems, dizziness, skin, eye, sinus

irritation, rash, headaches, sore throats, wheezing and nausea • EPA estimates that 1 of every 5,000 people who live in

manufactured homes for more than 10 years will develop cancer from formaldehyde exposure.

Four most dangerous indoor air pollutants (cont)

• Radioactive radon-222 gas• Seep into houses from underground rock deposits• Colorless odorless radioactive gas produced by the

natural decay of uranium-238.• lung tissue damage, lung cancer• Estimated that 7,000 to 30,000 Americans die each

year from radon-induced lung cancer• Only smoking causes more lung cancer deaths• Smokers more at risk than non-smokers

• Very small particles• Asbestos• Irritate the nose and throat, damage the lungs,

aggravate asthma and bronchitis, and shorten life.

Science: Sources and Paths of Entry for Indoor Radon-222 Gas

(From: http://www.epa.gov/iaq/radon/zonemap.html)

Zone pCi/L 1 >4 2 2 - 4 3 <2

Other possible indoor air pollutants• Pesticide residue• Pb particles• Living organisms and their excrements• E.g., Dust mites and cockroach droppings

• Airborne spores of molds and mildews

Science: Magnified View of a Household Dust Mite in a Dust Ball

Some Important Indoor Air Pollutants

Fig. 18-16, p. 484

Source: Chlorine-treated water in hot showers Possible threat: Cancer

Source: Air fresheners, mothball crystals Threat: Cancer

Source: Dry-cleaning fluid fumes on clothes Threat: Nerve disorders, damage to liver and kidneys, possible cancer

Source: Aerosol sprays Threat: Dizziness, irregular breathing

1,1,1-Trichloroethane

Source: Furniture stuffing, paneling, particleboard, foam insulation Threat: Irritation of eyes, throat, skin, and lungs; nausea; dizziness

Formaldehyde

Styrene

Nitrogen oxides Source: Carpets, plastic products Threat: Kidney and liver damage

Source: Unvented gas stoves and kerosene heaters, woodstoves Threat: Irritated lungs, children's colds, headaches

Source: Tobacco smoke, woodstoves Threat: Lung cancer

Benzo- α -pyrene

Particulates

Source: Pollen, pet dander, dust mites, cooking smoke particles Threat: Irritated lungs, asthma attacks, itchy eyes, runny nose, lung disease

Source: Radioactive soil and rock surrounding foundation, water supply Threat: Lung cancer

Radon-222

Tobacco smokeSource: Cigarettes Threat: Lung cancer, respiratory ailments, heart disease

Asbestos Carbon monoxide Methylene chlorideSource: Pipe insulation, vinyl ceiling and floor tiles Threat: Lung disease, lung cancer

Source: Faulty furnaces, unvented gas stoves and kerosene heaters, woodstoves Threat: Headaches, drowsiness, irregular heartbeat, death

Source: Paint strippers and thinners Threat: Nerve disorders, diabetes

Chloroform Para-dichlorobenzene Tetrachloroethylene

Sick Building Syndrome (SBS)Sick Building Syndrome (SBS)

Building Related Illness (BRI)Building Related Illness (BRI)

Sick Building Syndrome

• A persistent set of symptoms in > 20% population

• Causes(s) not known or recognizable• Complaints/Symptoms relieved after

exiting building • Linked to inadequate ventilation, new

buildings that contain chemicals such as formaldehyde from building products, or biological contaminants like mold or pollen.

Complaints/Symptoms

• Headaches• Fatigue• Reduced Mentation• Irritability • Eye, nose or throat

irritation

• Dry Skin• Nasal Congestion• Difficulty Breathing• Nose Bleeds• Nausea

Building Related Illness

• Clinically Recognized Disease

• Exposure to indoor air pollutants

• Recognizable Causes

Clinically Recognized Diseases

–Pontiac Fever – Legionella spp.–Legionnaire's Disease–Hypersensitivity Pneumonitis–Humidifier Fever–Asthma–Allergy–Respiratory Disease

• Chronic Obstructive Pulmonary Disease

18-5 Your Body’s Natural Defenses against Air Pollution Can Be Overwhelmed

Respiratory system protection from air pollutants• Hair in nose, cilia, mucus, sneezing, and

coughing

Effect of smoking and prolonged air pollution exposure• Chronic bronchitis• Emphysema- irreversible damage to the air sacs

in the lungs

Major Components of the Human Respiratory System

Normal Human Lungs and the Lungs of a Person Who Died of Emphysema

Air Pollution Is a Big Killer

3 Million deaths per year world-wide• Mostly in Asia• Main causes• Heart attacks, respiratory diseases, and lung

cancer

EPA: proposed stricter emission standards for diesel-powered vehicles

Link between international trade and air pollution• Cargo ships and pollution

Premature Deaths from Air Pollution in the U.S.

18-6 Laws and Regulations Can Reduce Outdoor Air Pollution (1)

United States• Clean Air Acts: 1970, 1977, and 1990

EPA • National ambient air quality standards (NAAQs)

for 6 outdoor criteria pollutants• National emission standards for 188 hazardous

air pollutants (HAPs)• Toxic Release Inventory (TRI)

Clean Air Act

Originally signed 1963• States controlled standards

1970 – Uniform Standards by Federal Govt.• Criteria Pollutants• Primary – Human health risk• Secondary – Protect materials, crops,

climate, visibility, personal comfort

Clean Air Act

1990 version • Acid rain, urban smog, toxic air pollutants, ozone

depletion, marketing pollution rights, VOC’s 1997 version• Reduced ambient ozone levels• Cost $15 billion/year -> save 15,000 lives • Reduce bronchitis cases by 60,000 per year• Reduce hospital respiratory admission 9000/year

PREVENTING AND REDUCINGAIR POLLUTION

The Clean Air Acts in the United States have

greatly reduced outdoor air pollution from

six major pollutants:• Carbon monoxide• Nitrogen oxides• Sulfur dioxides• Suspended particulate matter (less than PM-

10)• Tropospheric Ozone

Laws and Regulations Can Reduce Outdoor Air Pollution (2)

Good news in U.S.• Decrease in emissions• Use of low-sulfur diesel fuel• Cuts pollution

Developing countries• More air pollution

Case Study: U.S. Air Pollution Can Be Improved

Rely on cleanup more than prevention of pollution

Raise fuel-efficiency for cars, SUVs, and light trucks

Better regulation of emissions of motorcycles and two-cycle gasoline engines

Regulate air pollution for oceangoing ships in American ports

Case Study: U.S. Air Pollution Can Be Improved (2)

Why are airports exempt from many regulations?

Regulate greenhouse gas emissions

Ultrafine particles are not regulated

Urban O3 levels too high

Case Study: U.S. Air Pollution Can Be Improved (3)

What about indoor air pollution?

Better enforcement of the Clean Air Acts

Intense pressure needed from citizens to make improvements

We Can Use the Marketplace to Reduce Outdoor Air Pollution

Emission trading or cap-and-trade program• Mixed reactions to program

• SO2 emissions down significantly

• NO2 will be tried in the future

There Are Many Ways to Reduce Outdoor Air Pollution

1980 –2006

• SO2 emissions from U.S. electric power plants decreased by 66%

• NOx emissions by 41%

• Particulate emissions by 28%

Older plants not governed by the same regulations

New cars have better emissions

Solutions: Stationary Source Air Pollution

Prevention of Air pollution

Catalytic converter to oxidize the sulfur to yield sulfur compounds.

A lime scrubber in a smokestack may be used In a wet scrubber, a slurry of lime mixed w/

water is sprayed across the exiting gases. The sulfur mixes w/ the calcium, forming the calcium sulfate, which falls to the bottom of the smokestack as bottom ash.

Most particulates are removed post combustion

Post combustion method

Electrostatic Precipitator

Dirty gas

Dust discharge

ElectrodesCleaned gas

Cleaned gas

Dirty gas

Baghouse Filter

Dust discharge

Cyclone Separator

Dirty gas

Dust discharge

Cleaned gas

Dirty gas

Dirty water

Cleanwater

Wet Scrubber

Wetgas

Cleaned gas

Solutions: Motor Vehicle Air Pollution, Prevention and Cleanup

Reducing Indoor Air Pollution Should Be a Priority

Greater threat to human health than outdoor pollution

What can be done? • Prevention• Cleanup

Movement of Air Into / Out of Homes Amount of air available to dilute pollutants• important indicator of the likely contaminant

concentration Indoor air can mix with outside air by three

mechanisms• infiltration• natural ventilation• forced ventilation

Movement of Air Into / Out of Homes Natural ventilation• air exchange that occurs when windows or doors are

opened to increase air circulation

Forced ventilation• mechanical air handling systems used to induce air

exchange using fans and blowers

Trade-offs• cut infiltration to decrease heating and cooling costs vs.

indoor air quality problems

Solutions: Indoor Pollution, Prevention and Cleanup or Dilution

What Can You Do? Indoor Pollution: Ways to Reduce Your Exposure

Solutions: Air Pollution, Ways to Prevent It Over the Next 30–40 Years

ABC Video: Clean Air Act

Air Pollution Chapter 18 Core Case Study: South Asias Massive Brown Cloud Asian Brown Cloud Causes...

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