Air & Air Pollution

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Air & Air Pollution

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Air & Air Pollution. See what you know. What is in the air? What is the difference between Global Warming and Climate Change? What causes Climate Change? What are the effects of Climate Change? What caused the hole in the ozone layer?. - PowerPoint PPT Presentation

Transcript of Air & Air Pollution

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See what you know

• What is in the air?• What is the difference between Global

Warming and Climate Change?• What causes Climate Change?• What are the effects of Climate Change?• What caused the hole in the ozone layer?

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Choosing sides• Whether climate change

is occurring or not, isn’t it better to be on the side that believes it is happening? How can changing our ways be a bad thing? Isn’t it better to error on the true side?

• Human-caused climate change is happening, ..It is happening faster than anyone predicted even a few years ago, and therefore we need to remind ourselves and negotiators need to remind themselves that the longer we delay, the more we will pay, both in terms of lives and in terms of money.

• - Robert Orr, a top UN official

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The A

tmosphere

Greenhouse gasses

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Atmospheric Gases

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Atmospheric pressure (millibars)

Temperature

ThermospherePressure

Mesopause

Heating via ozoneMesosphere

Stratopause

Alti

tude

(kilo

met

ers)

Stratosphere Alti

tude

(mile

s)

TropopauseOzone “layer”

Heating from the earthTroposphere

Temperature (˚C)

Pressure = 1,000 millibars at ground level

(Sea level)

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1atm = 29.92 Inches of Hg1 atm = 14.696 lb/in2

• Inches of Hg• 1 atm = 29.92 Inches

of Hg

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The Atmosphere in layersTroposphere

– Layer in which we live– Most weather occurs here– 90% of the gasses are here– 0-6 mile above N and S Pole

• Mount Everest is 5.3 miles tall– 0-10 miles above equator– is made up mostly of nitrogen

and oxygen, with smaller amounts of water vapor and CO2

• Stratosphere– 6-10 mile thick– Air traffic due to lack of

weather– Ozone layer

• Thermosphere– 50 miles to space

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“Good” Ozone Layer• Ozone (O3) is a gas that occurs both in the Earth's upper

atmosphere and at ground level. Ozone can be "good" or "bad" for your health and the environment, depending on its location in the atmosphere.

• How much of our atmosphere is ozone?• Ozone that surrounds the earth 12-35 miles above the

earth is our first line of defense of the sun’s ultraviolet radiation. UVA, UVB, UVC– This radiation can cause sunburn, skin cancer, cataracts, …

• Ozone is constantly created and destroyed

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Humans need a small amount of ultraviolet radiation to maintain health. Ultraviolet radiation activates vitamin D in the human body, which assists the intestines in absorbing minerals. Humans, as well as other life forms, can tolerate radiation through the UVA range, but radiation with shorter wavelengths, such as UVB and UVC is harmful. Oxygen molecules absorb the shortest and most harmful UVC radiation and ozone absorbs most of the remainder before it reaches the earth’s surface. Ozone, a molecule containing three oxygen atoms, is made when the shortest wavelengths of UVC are absorbed by oxygen and break apart into two oxygen atoms.

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What Happens to Solar Energy Reaching the Earth?

• Solar energy flowing through the biosphere warms the atmosphere, evaporates and recycles water, generates winds and supports plant growth.

Figure 3-8

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Why is a sunset red?Refraction – of light as it passes through atmosphere and collides with atmospheric gasses. Colors are filtered out and scattered.

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The Natural Greenhouse Effect• Three major factors shape the earth’s

climate:– The sun.– Greenhouse effect that warms the earth’s lower

troposphere and surface because of the presence of greenhouse gases.

– Oceans store CO2 and heat, evaporate and receive water, move stored heat to other parts of the world.

– Natural cooling process through water vapor in the troposphere (heat rises).

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Major Greenhouse Gases• The major greenhouse gases in the lower

atmosphere are water vapor(.04%), carbon dioxide (.0369%), methane(.00018%), and nitrous oxide(.0000315%), ozone (.000005%)– These gases have always been present in the

earth’s troposphere in varying concentrations.– Fluctuations in these gases, plus changes in solar

output are the major factors causing the changes in tropospheric temperature over the past 400,000 years.

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Greenhouse Effect• This “greenhouse

effect” is vital for our survival. Without heat trapping gasses our planet would be cold and lifeless.

• The gasses act like a car that gets hot inside.

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Albedo - %age of incoming sunlight reflected from a surface

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Air Pollution – The Big 5• Air Pollutant is defined as

any substance in the air that is concentrated enough to harm living things or to cause damage to man-made objects.

• Primary pollutants – released directly into air.

• Secondary pollutants – primary pollutants react with other components.

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Fig. 19-3, p. 442

Primary Pollutants

CO CO2 Secondary PollutantsSO2 NO NO2

Most hydrocarbons - VOCs SO3

Most suspended particles HNO3H2O2 O3 PANs

Most NO3– and SO4

2– saltsSources Natural Stationary

Mobile

H3SO4

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Point Source / Nonpoint Source

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Human Actions and Our Environment

• When the human population was low, there was very little impact to the environment.– Wind, rain, and time were the natural air

cleaners.• As the human population increased, time

could not clean the air fast enough.• Deforestation removes CO2 cleaners.

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Human Actions and Our Environment

• The burning of fossil fuels -- notably coal, oil and gas -- has accounted for about 80 percent of the rise of atmospheric carbon dioxide since the pre-industrial era. Humans have been burning fossil fuel for 400 years adding an enormous unnatural amount of carbon dioxide and other gases in the air.

• The human impact has changed three major ecosystem cycles.

1. The chemical cycles– Carbon Cycle– Nitrogen Cycle– Sulfur Cycle

– By adding more chemicals we change the cycle

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Air Pollution – The Big 51. Carbon oxides

• High levels can suffocate you blood• Put out by automobiles and fires

2. Unburned Hydrocarbons - VOCs• Combustion of gas• Oil based paint, dry cleaning fluids, petroleum fuels• Methane stores 25 x more energy than CO2.

3. Nitrogen Oxides• Nitrogen alone is Ok, but at high temps. It reacts with oxygen to

form NOx• Makes the sky Brown in smog• Photchemical smog – nitrogen and light form “bad “ozone”• PANs – Peroxyacyl nitrates

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Air Pollution – The Big 5

• 4. Sulfur Oxides– Naturally occurring

• Volcanoes– Burning of coal, oil, gas (cars)– Cause Lung damage, asthma, and bronchitis– Combines with hydrogen to make Sulphuric Acid (ACID RAIN)

• 5. Particulates • - PM10 – smaller than 10 um – human hair is about 50-100 um

– Small solid particles or liquid droplets in the air• Light enough to float in air• Dust, lead, mercury, radon, ash from fires, road dust, exhaust, wind erosion,

• Lung irritant, stain buildings, reduce visibility

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Major Air Pollutants• Carbon oxides – CO , CO2:

– CO2 (10,000 ppm) will make some people feel drowsy. Exhaling into a bag is about 37,000 ppm.

– Carbon oxides are highly toxic gasses that form during the incomplete combustion of carbon-containing materials.

– 93% of carbon dioxide (CO2) in the troposphere occurs as a result of the carbon cycle.

– 7% of CO2 in the troposphere occurs as a result of human activities (mostly burning fossil fuels).

– CO2 is a greenhouse gas

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Major Air Pollutants

• Nitrogen oxides and nitric acid: – Nitrogen oxide (NOx) forms when nitrogen

and oxygen gas in air react at the high-combustion temperatures in automobile engines and coal-burning plants. NO can also form from lightening and certain soil bacteria.

– Photochemical Smog• NO reacts with air to form NO2.• NO2 reacts with water vapor in the air to form nitric

acid (HNO3) and nitrate salts (NO3-) which are

components of acid deposition.

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The Nitrogen Cycle:

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The first thing that starts the chain of events is that people start driving in the morning.  As gasoline is burned, nitrogen (N2) in the atmosphere is also burned, or oxidized, forming nitric oxide (NO)

N2 + O2=2NO Hydrocarbons and carbon monoxide (CO) will also be emitted by cars.   Hydrocarbons

are volatile organic compounds that may include acetaldehyde, formaldehyde, ethylene, and many other compounds.

In the air, nitric oxide combines with molecular oxygen to form nitrogen dioxide within a few hours.

2NO +  O2--------->2NO2Nitrogen dioxide absorbs light energy and splits to form nitric oxide and atomic oxygen:

NO2-->NO + OThen, in sunlight, the atomic oxygen combines with oxygen gas to form ozone (O3):

O+ O2--->O3 If no other factors are involved, ozone and nitric oxide then react to form nitrogen

dioxide and oxygen gas. O3 + NO<------>NO2 + O2

This last reaction can go in either direction, depending on temperature and the amount of sunlight.  If there is a lot of sunlight, the equation moves to the left, and more ozone is produced.  If nothing else gets in the way, an equilibrium is reached, and the ozone level stabilizes.

However, there is something else involved.  Remember that the cars are also emitting hydrocarbons as well as oxides of nitrogen.  Hydrocarbons are the other main ingredient in photochemical smog.  When hydrocarbons are present, nitric oxide reacts with them instead of the ozone. This reaction produces a variety of toxic products, such as a volatile compound known as PAN (peroxyacetyl nitrate).

NO + hydrocarbons----------------->PAN and various other compounds.   Also,NO2 +hydrocarbons------------------>PAN and various other compounds

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Major Air Pollutants

• Volatile organic compounds (VOCs):

– Most are hydorcarbons emitted by the leaves of many plants.

– About two thirds of global methane CH4 emissions comes from human sources.

– Other VOCs include industrial solvents such as trichlorethylene (TCE), benzene, and vinyl chloride, hundreds more.• Long-term exposure to benzene can cause cancer,

blood disorders, and immune system damage.

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Methane CH4• About 25x stronger GHG

than CO2.• 1/3rd of methane

emissions come from natural sources, mostly plants, wetlands, termites, anaerobic decomposition.

• The rest comes from human sources such as rice paddies, landfills, oil and natural gas wells, and cows (from belching or flatulence).

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Major Air Pollutants• Ozone (O3):

– “bad” ozone - found in troposphere

– Is a highly reactive gas that is a major component of photochemical smog.

– It can • Cause and

aggravate respiratory illness such as asthma

• Can aggravate heart disease.

• Damage plants

What Causes "Bad" Ozone?Ground-level or "bad" ozone is not emitted directly into the air, but is created by chemical reactions VOC + NOx + Sunlight = Ozone (O3)Emissions from industrial facilities and electric utilities, motor vehicle exhaust, gasoline vapors, and chemical solvents are some of the major sources of NOx and VOC.

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Ozone Action Days

• Usually occur days that are:– Relatively Hot– Dry– Clear– Little to no wind

• Ozone action days can be predicted

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Major Air Pollutants

• Sulfur dioxide (SO2) and sulfuric acid:– About one-third of SO2 in the troposphere

occurs naturally through the sulfur cycle.– Two-thirds come from human sources, mostly

combustion (S+ O2 SO2) of sulfur-containing coal and from oil refining and smelting of sulfide ores.

– SO2 in the atmosphere can be converted to sulfuric acid (H2SO4) and sulfate salts (SO4

2-) that return to earth as a component of acid deposition.

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Sulfur in from burning of fuels.

• Combustion of gas in automobiles releases sulfur.

• Burning of coal releases sulfur. The United States creates a great majority of its electricity by burning coal.

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The Sulfur Cycle

Figure 3-32

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ACID DEPOSITION

• Sulfur dioxides, nitrogen oxides, and particulates can react in the atmosphere to produce acidic chemicals that can travel long distances before returning to the earth’s surface.– Tall smokestacks reduce local air pollution but

can increase regional air pollution.

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Acid Deposition• AKA Acid Rain• Rain cleans the air, but pollutes the water.• Normal rainwater has a pH of 5.6 (slightly

acidic). This is because it is exposed to the carbon dioxide in the atmosphere. The carbon dioxide gets dissolved in the rainwater and forms carbonic acid (H{-2}CO{-3}). Acid Rain is anything below 5.6.

• Plants like to grown in soil with a pH of 6-7• What happens to the plants?

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Fig. 19-6, p. 448

WindTransformation to sulfuric acid (H2SO4) and nitric acid (HNO3)

Windborne ammonia gas and particles of cultivated soil partially neutralize acids and form dry sulfate and nitrate salts

Wet acid depostion (droplets of H2SO4 and HNO3 dissolved in rain and snow)Nitric oxide (NO)

Sulfur dioxide (SO2) and NO

Dry acid deposition (sulfur dioxide gas and particles of sulfate and nitrate salts)

Acid fogFarm

OceanLakes in deep

soil high in limestone are

buffered

Lakes in shallow soil low in limestone

become acidic

ACID RAIN

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ACID DEPOSITION

• pH measurements in relation to major coal-burning and industrial plants.

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ACID DEPOSITION

• Air pollution is one of several interacting stresses that can damage, weaken, or kill trees and pollute surface and groundwater.

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ACID DEPOSITION

• Acid deposition contributes to chronic respiratory disease and can leach toxic metals (such as lead and mercury) from soils and rocks into acidic lakes used as sources for drinking water.

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Fig. 19-10, p. 452

SolutionsAcid Deposition

Prevention Cleanup Reduce air pollution by improving energy efficiency

Add lime to neutralize acidified lakes

Reduce coal useAdd phosphate fertilizer to neutralize acidified lakes

Increase natural gas use

Increase use of renewable energy resources

Burn low-sulfur coal

Remove SO2 particulates & NOx from smokestack gases

Remove NOx from motor vehicular exhaust

Tax emissions of SO2

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Major Air Pollutants

• Suspended particulate matter (SPM):– Consists of a variety of solid particles and

liquid droplets small and light enough to remain suspended in the air.

– The most harmful forms of SPM are fine particles (PM-10, with an average diameter < 10 micrometers) and ultrafine particles (PM-2.5).

– According to the EPA, SPM is responsible for about 60,000 premature deaths a year in the U.S.

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SPMs• Lead• Mercury• Pollen• Soil• Liquids

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What is Happening to the "Good" Ozone Layer?

Ozone is produced naturally in the stratosphere. But this "good"ozone is gradually being destroyed by man-made chemicals referredto as ozone-depleting substances (ODS), includingchlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs),halons, methyl bromide, carbon tetrachloride, and methyl chloroform.These substances were formerly used and sometimes still are used incoolants, foaming agents, fire extinguishers, solvents, pesticides, andaerosol propellants (propane).

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Fig. 19-2, p. 440

Atmospheric pressure (millibars)

Temperature

ThermospherePressure

MesopauseHeating via ozone

Mesosphere

Stratopause

Alti

tude

(kilo

met

ers)

Stratosphere Alti

tude

(mile

s)

TropopauseOzone “layer”

Heating from the earthTroposphere

Temperature (˚C)

Pressure = 1,000 millibars at ground level

(Sea level)

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Ozone• CFC – Chlorofluorocarbons react with an

oxygen atom to break down O3 to O2.• 1 chlorine can destroy 100,000 ozone molecules• As ozone is broken down, the ozone layer gets

thinner. – This radiation that gets through can cause sunburn,

skin cancer, cataracts, …

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Fig. 20-18, p. 486

A free oxygen atom pulls the oxygen atom off the chlorine monoxide molecule to form O2.

Ultraviolet light hits a chlorofluorocarbon (CFC) molecule, such as CFCl3, breakingoff a chlorine atom and leaving CFCl2. Sun

Repeated many times

The chlorine atom and the oxygen atom join to form a chlorine monoxide molecule (ClO).

Summary of ReactionsCCl3F + UV Cl + CCl2FCl + O3 ClO + O2Cl + O Cl + O2

UV radiation

The chlorine atom attacksan ozone (O3) molecule, pulling an oxygen atom offit and leaving an oxygen molecule (O2).

Once free, the chlorine atom is off to attack another ozone moleculeand begin the cycle again.

Cl

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OZONE DEPLETION IN THE STRATOSPHERE

• Since 1976, in Antarctica, ozone levels have markedly decreased during October and November.

Figure 20-20

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Human Health• Worse sunburn• More eye cataracts• More skin cancers• Immune system suppression

Food and Forests• Reduced yields for some crops• Reduced seafood supplies from reduced phytoplankton• Decreased forest productivity for UV-sensitive tree species

Wildlife• Increased eye cataracts in some species• Decreased population of aquatic species sensitive to UV radiation• Reduced population of surface phytoplankton• Disrupted aquatic food webs from reduced phytoplankton

Air Pollution and Materials• Increased acid deposition• Increased photochemical smog• Degradation of outdoor paints and plastics

Global Warming• Accelerated warming because of decreased ocean uptake of CO2 from atmosphere by phytoplankton and CFCs acting as greenhouse gases

Effects of Ozone DepletionNatural Capital Degradation

Fig. 20-21, p. 488

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Montréal Protocol• The Montreal Protocol, adopted in 1987, required

nations to freeze production levels of CFCs. Additional agreements enacted since 1987 accelerated the CFC phase out timetable to December 31, 1995.

• Atmospheric concentrations of chlorofluorocarbons peaked in 1994 and began to decrease in 1995, marking the first time that a atmospheric concentrations of chlorine began to decrease. Chlorine concentrations in July 2002, were about 5% less than the 1994 peak. However, the amount of atmospheric bromine continues to increase, albeit at a slower rate.

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Fig. 20-23, p. 490

What Can You Do?

• Stay out of the sun, especially between 10 A.M. and 3 P.M.

• Do not use tanning parlors or sunlamps.

• When in the sun, wear protective clothing and sun– glasses that protect against UV-A and UV-B radiation.

• Be aware that overcast skies do not protect you.

• Do not expose yourself to the sun if you are takingantibiotics or birth control pills.

• Use a sunscreen with a protection factor of 15 or 30

anytime you are in the sun if you have light skin. • Examine your skin and scalp at least once a month for moles or warts that change in size, shape, or color or sores that keep oozing, bleeding, and crusting over. Ifyou observe any of these signs, consult a doctor immediately.

Reducing Exposure to UV Radiation

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Topography and Pollution• Geography can effect

pollution concentrations.

• Mountainous areas tend to trap pollution

• Flat areas tend to allow pollution to disperse

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• Forest Fires in the Los Angeles area.

• Winds carry the smoke across the ocean.

• Wind can clean the air, but it can also spread it somewhere else.

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China Air Pollution• A regions air pollution

can become a global problem.

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Temperature Inversion

• Cold air is more dense. Sometimes when it sinks below the warm air, it brings the pollution with it.

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Temperature Inversions

• Cold, cloudy weather in a valley surrounded by mountains can trap air pollutants (left).

• Areas with sunny climate, light winds, mountains on three sides and an ocean on the other (right) are susceptible to inversions.

Figure 19-5

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How does air quality effect me?

• Asthma• Emphysema• Allergies• Heart disease• Drink polluted water• Colds• Pneumonia

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National Ambient Air Quality Standards (NAAQS)

• Sets acceptable concentrations for 6 “criteria” pollutants that:– Threaten public health/the environment

over broad areas (non-point)– Are emitted in large quantities– CO, Pb, Nitrogen Oxides, Ozone,

Particulate Matter and Sulfur Dioxides

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HEALTH EFFECTS OF AIR POLLUTION

• Your respiratory system can help protect you from air pollution, but some air pollutants can overcome these defenses. Figure 19-14

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Air Pollution is a Big Killer

• Each year, air pollution prematurely kills about 3 million people, mostly from indoor air pollution in developing countries.– In the U.S., the EPA

estimates that annual deaths related to indoor and outdoor air pollution range from 150,000 to 350,000.

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HEALTH EFFECTS OF AIR POLLUTION

Normal human lungs (left) and the lungs of a person who died of emphysema (right).

Figure 19-15

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Air Pollution is a Big Killer

• Spatial distribution of premature deaths from air pollution in the United States.

Figure 19-16

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Clean Air Act• 1963 - first passage • 1970, 1977 and 1990 - amended• Involves EPA• Sets standards for acceptable levels of sulfur

oxides, nitrogen oxides, ozone, carbon monoxide, hydrocarbons, lead, PANs, particulate matter & more. Does not regulate CO2.

• Provides pollution credits (subsidies) for industries that utilize pollution-control devices+

• Bush administration has relaxed rules• Does not regulate 2&4 cycle small engines

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PREVENTING AND REDUCING AIR POLLUTION

• Environmental scientists point out several deficiencies in the Clean Air Act:– The U.S. continues to rely on cleanup rather than

prevention.– The U.S. Congress has failed to dramatically

increase fuel-efficiency standards for automobiles.– Regulation of emissions from motorcycles and two-

cycle engines remains inadequate.– There is little or no regulation of air pollution from

oceangoing ships in American ports.

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PREVENTING AND REDUCING AIR POLLUTION

• Executives of companies claim that correcting these deficiencies would cost too much, harm economic growth, and cost jobs.

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What Is Being Done About "Bad" Ozone?

Under the Clean Air Act, EPA has set protective health-based standards for ozone in the air we breathe. EPA, state, and cities have instituted a variety of multi-faceted programs to meet these healthbased standards. Throughout the country, additional programs are being put into place to cut NOx and VOC emissions from vehicles, industrial facilities, and electric utilities. Programs are also aimed at reducing pollution by reformulating fuels and consumer/commercial products, such as paints and chemical solvents, that contain VOC.

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PCBs

• Polychlorinated biphenyls (PCBs) were widely used as dielectric and coolant fluids. Due to PCBs' environmental toxicity and classification as a persistent organic pollutant, PCB production was banned by the United States Congress in 1979 and by the Stockholm Convention on Persistent Organic Pollutants in 2001.

• A number of peer-reviewed health studies have shown an association between exposure to PCBs and non-Hodgkin Lymphoma, a frequently fatal form of cancer

• Concerns about the toxicity of PCBs are largely based on compounds within this group that share a structural similarity and toxic mode of action with dioxin. Toxic effects such as endocrine disruption and neurotoxicity are also associated with other compounds within the group. 

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Solutions: Reducing Outdoor Air Pollution

• There are a of ways to prevent and control air pollution from motor vehicles.– Because of the Clean Air Act, a new car today

in the U.S. emits 75% less pollution than it did pre-1970 cars.

– There is an increase in motor vehicle use in developing countries and many have no pollution control devices and burn leaded gasoline.

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Fig. 19-19, p. 460

Solutions

Motor Vehicle Air Pollution

Prevention Cleanup Emission control devices

Mass transit

Bicycles and walking

Less polluting engines

Less polluting fuels

Improve fuel efficiency

Car exhaust inspections twice a year

Get older, polluting cars off the road

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

Stricter emission standards

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Solutions: Reducing Outdoor Air Pollution

• There are a of ways to prevent and control air pollution from coal-burning facilities.– Electrostatic precipitator: are used to attract

negatively charged particles in a smokestack into a collector.

– Wet scrubber: fine mists of water vapor trap particulates and convert them to a sludge that is collected and disposed of usually in a landfill.

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Electrostatic Precipitator• Can remove 99% of

particulate matter• Does not remove

hazardous ultrafine particles.

• Produces toxic dust that must be safely disposed of.

• Uses large amounts of electricity

Figure 19-18

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Wet Scrubber

• Can remove 98% of SO2 and particulate matter.

• Not very effective in removing hazardous fine and ultrafine particles.

Figure 19-18