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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
6
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
What Are the Major Outdoor Air Pollutants?
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.
What Are the Major Outdoor Air Pollutants?
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
What Are the Major Outdoor Air Pollutants?
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.
What Are the Major Outdoor Air Pollutants?
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
Indoor Air Pollution Is a Serious Problem
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
Indoor Air Pollution Is a Serious Problem
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
Indoor Air Pollution Is a Serious Problem
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)
vsvs
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
Bags
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