Chapter 18:Chapter 18:

Air PollutionAir Pollution

Atmosphere Review

Troposphere: Layer closest to earth Most dense layer Extends only 17 km (11 miles) above

sea level at the equator and 6 km (4 miles) at the poles

Apple analogy: the troposphere would be no thicker than the apple’s skin

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Make-up of Troposphere 99% is comprised of two gasses:

Nitrogen (78%) and Oxygen (21%) Remainder:

Water vapor (0.01% at the poles, 4% in the tropics)

0.93% argon 0.040% carbon dioxide Trace amounts of dust and soot particles Trace amounts other gasses (methane,

ozone, nitrous oxide) 33

OverviewOverview Air Pollution in the Lower Air Pollution in the Lower

AtmosphereAtmosphere Controlling Common Pollutants of the Controlling Common Pollutants of the

Lower AtmosphereLower Atmosphere High Altitude Ozone DepletionHigh Altitude Ozone Depletion Indoor Air PollutionIndoor Air Pollution Controlling Indoor Air PollutionControlling Indoor Air Pollution

Air Pollution in Lower Air Pollution in Lower AtmosphereAtmosphere

A brief historyA brief history The atmosphere has long been a sink The atmosphere has long been a sink

for waste disposalfor waste disposal Long history of recognition of the Long history of recognition of the

existence of atmospheric pollutantsexistence of atmospheric pollutants Natural photochemical smog recognized Natural photochemical smog recognized

in 1550in 1550 Acid rain first described in 17Acid rain first described in 17thth century century Word smog introduced in 1905Word smog introduced in 1905

Mixture of smoke and fogMixture of smoke and fog

Does Alabama require smog emission testing for vehicles? http://dmvanswers.com/questions/34

24/What-are-the-AL-emissions-or-smog-check-requirements-for-vehicle-registration

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Two Main Sources of Pollution1. Natural releases from the environment

2. Created by humans

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Nature as a Polluter

Pollen Dust Particles Mold Spores Forest Fires Volcanic Gases Dinoflagellates – red tides – cause

respiratory distress in humans

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How Air Pollution Affects Humans Severe: can be lethal Can just be simply aggravating

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Human Pollution NOT a new phenomenon

Early man – fire Romans smelting of lead resulted in air

pollution that drifted thousands of miles from the source – has been discovered trapped in the ice of Greenland!

Industrial Revolution – large-scale production of pollutants Fossil fuel introduction into the

atmosphere1010

Terms you need to know in order to discuss pollution Primary pollutants: those that are

released directly into the lower atmosphere; these are toxic Ex: Carbon monoxide

Secondary pollutants: those that are formed by the combination of primary pollutants in the atmosphere Ex: Acid Rain – produced from the

combination of sulfur oxides and water vapor

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Sources of Pollution Stationary sources: factories or power

plants Moving sources: cars

Point source pollution: describes a specific location from which pollution is released Ex: a factory or a site where wood is being burned

Non-point source pollution: pollution that does not have a specific point of release Ex: a combination of many sources – the number of

cows releasing methane gas within a few square miles

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The Two Main Types of Air The Two Main Types of Air PollutionPollution Two categoriesTwo categories1.1. Stationary sources - those that have a Stationary sources - those that have a

relatively fixed locationrelatively fixed location Point sources Point sources

emit pollutants from controllable sitesemit pollutants from controllable sites Fugitive sources Fugitive sources

generate air pollutants from open areas exposed to generate air pollutants from open areas exposed to wind processeswind processes

Area sources Area sources well defined areas within which are several sources well defined areas within which are several sources

of air pollutantsof air pollutants

Point sourcePoint source

Examples of Stationary Examples of Stationary SourcesSources

Fugitive sourceFugitive source

Air Pollution in Lower Air Pollution in Lower AtmosphereAtmosphere

2.2. Mobile source - move from place to Mobile source - move from place to place while emitting pollutantsplace while emitting pollutants

Automobiles, trucks, buses, aircraft, Automobiles, trucks, buses, aircraft, ships, and trains.ships, and trains.

General Effects of Air General Effects of Air PollutionPollution Affects many aspects of our Affects many aspects of our

environmentenvironment Visual qualitiesVisual qualities VegetationVegetation AnimalsAnimals Soil Soil Water qualityWater quality Natural and artificial structuresNatural and artificial structures Human healthHuman health

General Effects of Air General Effects of Air PollutionPollution

Significant factor in human death Significant factor in human death rate for many large citiesrate for many large cities Athens, GreeceAthens, Greece

Number of deaths higher on bad air quality Number of deaths higher on bad air quality daysdays

HungaryHungary 1 in 17 deaths contributed to air pollution1 in 17 deaths contributed to air pollution

USUS 300,000 deaths/year, health cost $50 billion300,000 deaths/year, health cost $50 billion

ChinaChina Large cities have major air pollution issues; Large cities have major air pollution issues;

health cost $50–$100 billionhealth cost $50–$100 billion

General Effects of Air General Effects of Air PollutionPollution Affect human health in several waysAffect human health in several ways

Toxic poisoning, cancer, birth defects, Toxic poisoning, cancer, birth defects, eye irritation, and irritation of eye irritation, and irritation of respiratory systemrespiratory system

Increased susceptibility to viral Increased susceptibility to viral infections, causing pneumonia and infections, causing pneumonia and bronchitisbronchitis

Increased susceptibility to heart diseaseIncreased susceptibility to heart disease Aggravation of chronic diseases, such as Aggravation of chronic diseases, such as

asthma and emphysemaasthma and emphysema

General Effects of Air General Effects of Air PollutionPollution Many air pollutants have synergistic Many air pollutants have synergistic

effectseffects Do greater damage to the lungs than a Do greater damage to the lungs than a

combination of the two pollutants would combination of the two pollutants would be expected to do based on their be expected to do based on their separate effectsseparate effects

Air PollutantsAir Pollutants 200 air pollutants recognized and 200 air pollutants recognized and

assessed by US EPA and listed in assessed by US EPA and listed in Clean Water ActClean Water Act Primary pollutantsPrimary pollutants

Emitted directly into the airEmitted directly into the air Carbon monoxide (58%), volatile organic Carbon monoxide (58%), volatile organic

compounds (11%), nitrogen oxides (15%), compounds (11%), nitrogen oxides (15%), sulfur oxides (13%), and particulates (3%)sulfur oxides (13%), and particulates (3%)

Secondary pollutantsSecondary pollutants Produced through reactions between Produced through reactions between

primary pollutants and normal atmospheric primary pollutants and normal atmospheric compoundscompounds

Air Pollution

Primary pollutants Secondary pollutants Sulfur oxides Stationary sources Moving sources Point source pollution Non-point source pollution

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Primary and Secondary Primary and Secondary PollutantsPollutants Natural pollutants exceed anthropogenic Natural pollutants exceed anthropogenic

pollutants (other than sulfur and nitrogen pollutants (other than sulfur and nitrogen oxides)oxides) Release of sulfur dioxide from volcanic eruptions. Release of sulfur dioxide from volcanic eruptions. Release of hydrogen sulfide Release of hydrogen sulfide

Geysers and hot springs Geysers and hot springs Biological decay in bogs and marshesBiological decay in bogs and marshes

Release of ozone in the lower atmosphere as a Release of ozone in the lower atmosphere as a result of unstable meteorological conditionsresult of unstable meteorological conditions

Emission of particles from wildfires and Emission of particles from wildfires and windstormswindstorms

Natural hydrocarbon seepsNatural hydrocarbon seeps

Criteria Pollutants – “The Criteria Pollutants – “The Dirty Half Dozen”Dirty Half Dozen” There are six criteria pollutants – There are six criteria pollutants –

these do the most harm to human these do the most harm to human health and welfarehealth and welfare Sulfur dioxideSulfur dioxide Nitrogen oxidesNitrogen oxides Carbon monoxideCarbon monoxide OzoneOzone ParticulatesParticulates LeadLead

Sulfur DioxideSulfur Dioxide

SOSO22

Colorless odorless gasColorless odorless gas Once emitted can be converted to Once emitted can be converted to

sulfatesulfate Removed from atmosphere by wet or Removed from atmosphere by wet or

dry depositiondry deposition Major human sources:Major human sources:

coal power plantscoal power plants industrial processesindustrial processes

Sulfur DioxideSulfur Dioxide

Adverse effects depend on dose and Adverse effects depend on dose and concentrationconcentration Injury or death to animals and plantsInjury or death to animals and plants Corrosion of paint and metalsCorrosion of paint and metals Important precursor to acid rainImportant precursor to acid rain

Nitrogen OxidesNitrogen Oxides

Occur in many forms in the Occur in many forms in the atmosphere but largely emitted in atmosphere but largely emitted in two forms:two forms: Nitric oxide - NONitric oxide - NO Nitrogen dioxide - NONitrogen dioxide - NO22

A yellow-brown to reddish-brown gasA yellow-brown to reddish-brown gas May be converted to NOMay be converted to NO33

2-2-

Both subject to emissions regulation Both subject to emissions regulation and contribute to smogand contribute to smog

NONO22 major contributor to acid rain major contributor to acid rain

Nitrogen OxidesNitrogen Oxides

Nearly all NONearly all NO22 emitted from human emitted from human sourcessources Combustion of fossil fuelsCombustion of fossil fuels

Environmental effectsEnvironmental effects Irritate eyes and mucous membranesIrritate eyes and mucous membranes Suppress plant growthSuppress plant growth

However, when convert to nitrate may However, when convert to nitrate may promote plant growthpromote plant growth

Carbon MonoxideCarbon Monoxide

CO is a colorless, odorless gasCO is a colorless, odorless gas Even at low concentrations is extremely Even at low concentrations is extremely

toxic to humanstoxic to humans Binds to hemoglobin in bloodBinds to hemoglobin in blood

90% of CO in atmosphere comes from 90% of CO in atmosphere comes from natural sourcesnatural sources

10% comes from fires, cars, and 10% comes from fires, cars, and incomplete burning of organic incomplete burning of organic compoundscompounds

Ozone and Other Ozone and Other Photochemical OxidantsPhotochemical Oxidants Photochemical oxidants result from Photochemical oxidants result from

atmospheric interactions of nitrogen atmospheric interactions of nitrogen dioxide and sunlightdioxide and sunlight Most common is ozone - OMost common is ozone - O33

Colorless gas with slightly sweet odorColorless gas with slightly sweet odor Very active chemically, oxidizes or Very active chemically, oxidizes or

burnsburns Beneficial in the upper atmosphereBeneficial in the upper atmosphere

Ozone and Other Ozone and Other Photochemical OxidantsPhotochemical Oxidants

Because ozone is a secondary Because ozone is a secondary pollutant it is difficult to regulate.pollutant it is difficult to regulate. Health standards often exceeded in Health standards often exceeded in

urban areasurban areas Effects includeEffects include

Kills leaf tissue at high concentrationKills leaf tissue at high concentration Damage eyes and respiratory systemDamage eyes and respiratory system Even young, healthy people may Even young, healthy people may

have breathing difficulty on polluted have breathing difficulty on polluted daysdays

Particulate MatterParticulate Matter

PM10 is made up of particles less PM10 is made up of particles less than 10μm in diameterthan 10μm in diameter Present everywhere but high Present everywhere but high

concentrations and/or specific types concentrations and/or specific types dangerousdangerous

Much particulate matter easily visible as Much particulate matter easily visible as smoke, soot, or dustsmoke, soot, or dust

Includes airborne asbestos and heavy Includes airborne asbestos and heavy metalsmetals

Particulate MatterParticulate Matter

Very fine pollutants - greatest concernVery fine pollutants - greatest concern PM 2.5 - less than 2.5 PM 2.5 - less than 2.5 μμm in diameterm in diameter Easily inhaled into the lungs, then absorbed Easily inhaled into the lungs, then absorbed

into the bloodstreaminto the bloodstream Ultrafine particles- <0.18 Ultrafine particles- <0.18 μμm released by m released by

automobilesautomobiles Often referred to as Total Suspended Often referred to as Total Suspended

Particles (TSPs)Particles (TSPs) Tend to be highest in large cities in developing Tend to be highest in large cities in developing

countriescountries

Particulate MatterParticulate Matter

Recent studies estimate that 2 to Recent studies estimate that 2 to 9% of human mortality in cites is 9% of human mortality in cites is associated with PMassociated with PM Linked to both lung cancer and Linked to both lung cancer and

bronchitisbronchitis Especially hazardous to elderly and Especially hazardous to elderly and

those with asthmathose with asthma Dust can be deposited on plantsDust can be deposited on plants

Interferes with absorption of COInterferes with absorption of CO22 and and OO22 and transpiration and transpiration

Particulate MatterParticulate Matter

Block sunlight and may cause Block sunlight and may cause climate changeclimate change

Global dimmingGlobal dimming Gradual reduction in the solar energy Gradual reduction in the solar energy

that reaches the surface of Earththat reaches the surface of Earth Cools the atmosphereCools the atmosphere Lessens global warmingLessens global warming

LeadLead

Lead is constituent of auto batteries Lead is constituent of auto batteries and was once added to gasolineand was once added to gasoline Lead in gas emitted into air with Lead in gas emitted into air with

exhaustexhaust Spread widely around world in soils and Spread widely around world in soils and

water along roadwayswater along roadways Once in soil can enter the food chainOnce in soil can enter the food chain Lead now removed from gas in US, CAN, Lead now removed from gas in US, CAN,

EUEU 98% reduction in emissions since 1970s98% reduction in emissions since 1970s

Air ToxicsAir Toxics

Known/suspected to cause cancer or Known/suspected to cause cancer or other serious health problems.other serious health problems. Associated with long-term and short-Associated with long-term and short-

term exposuresterm exposures Gases, metals, and organic chemicals Gases, metals, and organic chemicals

that are emitted in relatively small that are emitted in relatively small volumesvolumes

Cause respiratory, neurological, Cause respiratory, neurological, reproductive, or immune diseasesreproductive, or immune diseases

Air ToxicsAir Toxics

Standards have been set for more Standards have been set for more than 150 air toxicsthan 150 air toxics Ex: hydrogen sulfide, hydrogen fluoride, Ex: hydrogen sulfide, hydrogen fluoride,

chlorine gases, benzene, methanol, chlorine gases, benzene, methanol, ammoniaammonia

EPA estimates that the average risk for EPA estimates that the average risk for cancer from exposure to air toxics is cancer from exposure to air toxics is about 1 in 21,000about 1 in 21,000

Hydrogen sulfideHydrogen sulfide

Highly toxic corrosive gas easily identified Highly toxic corrosive gas easily identified by its rotten egg odorby its rotten egg odor

Produced from Produced from Natural sources such as geysers, swamps, and Natural sources such as geysers, swamps, and

bogs bogs Human sources such as industrial plants that Human sources such as industrial plants that

produce petroleum or that smelt metalsproduce petroleum or that smelt metals Effects of hydrogen sulfideEffects of hydrogen sulfide

Functional damage to plants Functional damage to plants Range from toxicity to deathRange from toxicity to death

Volatile Organic Compounds Volatile Organic Compounds (VOC)(VOC)

Variety of organic compounds used Variety of organic compounds used as solvents in industrial processes as solvents in industrial processes Dry cleaning, degreasing, and graphic Dry cleaning, degreasing, and graphic

artsarts HydrocarbonsHydrocarbons

Comprise one group of VOCsComprise one group of VOCs Thousands of hydrocarbon compounds Thousands of hydrocarbon compounds

exist, including natural gas, or methane exist, including natural gas, or methane (CH(CH44); butane (C); butane (C44HH1010); and propane ); and propane (C(C33HH88))

Volatile Organic CompoundsVolatile Organic Compounds

Some VOCs react w/ sunlight to Some VOCs react w/ sunlight to produce photochemical smogproduce photochemical smog

Globally 15% of hydrocarbons Globally 15% of hydrocarbons emissions are anthropogenicemissions are anthropogenic In the US - 50%In the US - 50% Primary human source automobilesPrimary human source automobiles

BenzeneBenzene

Additive in gasoline and an Additive in gasoline and an important industrial solventimportant industrial solvent

Produced during incomplete Produced during incomplete combustioncombustion Also component of cigarette smokeAlso component of cigarette smoke Major environmental source on and off Major environmental source on and off

road vehiclesroad vehicles

ArcoleinArcolein

A volatile hydrocarbon that is A volatile hydrocarbon that is extremely irritating to nose, eyes, extremely irritating to nose, eyes, and respiratory systemand respiratory system

Produced fromProduced from Manufacturing processes that involve Manufacturing processes that involve

combustion of petroleum fuelscombustion of petroleum fuels Component of cigarette smokeComponent of cigarette smoke

Urban Air PollutionUrban Air Pollution

SmogSmog Term first used in 1905 as mixture of Term first used in 1905 as mixture of

smoke and fog that produced unhealthy smoke and fog that produced unhealthy airair

Two major typesTwo major types Photochemical smog (LA type smog or Photochemical smog (LA type smog or

brown air)brown air) Directly related to automobile useDirectly related to automobile use

Sulfurous smog (London type smog, Sulfurous smog (London type smog, gray air, or industrial smog)gray air, or industrial smog)

Produced by combustion of coal or oil Produced by combustion of coal or oil

Urban Air PollutionUrban Air Pollution

Whether air pollution develops Whether air pollution develops depends on topography and depends on topography and meteorological conditionsmeteorological conditions Determine whether air pollution is a Determine whether air pollution is a

nuisance or major health problemnuisance or major health problem Primary adverse effectPrimary adverse effect

Damage to green plants and Damage to green plants and aggravation of chronic diseaseaggravation of chronic disease

Usually low-level over long period of Usually low-level over long period of timetime

However major disaster have occurredHowever major disaster have occurred

Urban Air PollutionUrban Air Pollution

In the lower atmosphere, restricted In the lower atmosphere, restricted circulation associated with inversion circulation associated with inversion layers may lead to pollution eventlayers may lead to pollution event

Atmospheric inversionAtmospheric inversion Occurs when warmer air is found above Occurs when warmer air is found above

cooler aircooler air

Occurs primarily in summer and fall

Occurs when cloud cover associated with stagnant air

Urban Air PollutionUrban Air Pollution

Cities situated in a valley or Cities situated in a valley or topographic bowl are more topographic bowl are more susceptible to smog problemssusceptible to smog problems Surrounding mountains and inversions Surrounding mountains and inversions

prevent pollutants from being prevent pollutants from being transported by wind or weather systemstransported by wind or weather systems

Ex: Los AngelesEx: Los Angeles

Potential for Urban Air Potential for Urban Air PollutionPollution

Determined by the following Determined by the following factors:factors:

1.1. Rate of emission of pollutants per unit Rate of emission of pollutants per unit areaarea

2.2. Downwind distance that a mass of air Downwind distance that a mass of air moves through an urban areamoves through an urban area

3.3. Average speed of the windAverage speed of the wind

4.4. Elevation to which potential pollutants Elevation to which potential pollutants can be thoroughly mixed by naturally can be thoroughly mixed by naturally moving air in the lower atmospheremoving air in the lower atmosphere

Urban Air PollutionUrban Air Pollution Concentration of pollutants in the air Concentration of pollutants in the air

is directly proportional to the first is directly proportional to the first two factorstwo factors As either emission rate or down wind As either emission rate or down wind

travel distance increase, so will the travel distance increase, so will the concentration of pollutantsconcentration of pollutants

City air pollution decreases with City air pollution decreases with increases in third and forth factorsincreases in third and forth factors The stronger the wind and the higher The stronger the wind and the higher

the mixing layer, the lower the pollutionthe mixing layer, the lower the pollution

Clean Air Act Amendments of Clean Air Act Amendments of 19901990 Regulations enacted by the U.S. Regulations enacted by the U.S.

Congress that address Congress that address Acid rainAcid rain Toxic emissionsToxic emissions Ozone depletionOzone depletion Automobile exhaustAutomobile exhaust Buying and selling of sulfur dioxide Buying and selling of sulfur dioxide

emissionsemissions Nitrogen dioxides- reduced by 10 million Nitrogen dioxides- reduced by 10 million

tonstons Toxins- especially those causing cancerToxins- especially those causing cancer

Air Quality IndexAir Quality Index

Used to describe air pollution on a Used to describe air pollution on a given daygiven day

Determined from measurements of Determined from measurements of the concentration of five major the concentration of five major pollutants:pollutants: Particulate matter, sulfur dioxide, Particulate matter, sulfur dioxide,

carbon monoxide, ozone, and nitrogen carbon monoxide, ozone, and nitrogen dioxide. dioxide.

Air Quality IndexAir Quality Index AQI = 100AQI = 100

Air is unhealthyAir is unhealthy AQI greater than 200AQI greater than 200

Air pollution alert is issued Air pollution alert is issued AQI exceeds 300AQI exceeds 300

Air pollution warning is issued - hazardous to Air pollution warning is issued - hazardous to all people. all people.

AQI exceeds 400AQI exceeds 400 Air pollution emergency is declared, and Air pollution emergency is declared, and

people are requested to remain indoors and people are requested to remain indoors and minimize physical exertionminimize physical exertion

Cost of Outdoor Air Pollution Cost of Outdoor Air Pollution ControlControl

Fossil fuel-burning pollution controlFossil fuel-burning pollution control A few hundred dollars per additional ton A few hundred dollars per additional ton

of particulates removedof particulates removed Aluminum plantAluminum plant

May be several thousand per tonMay be several thousand per ton Cost benefit must be consideredCost benefit must be considered

Ozone Depletion Ozone Depletion

Ozone (OOzone (O33) ) Triatomic form of oxygen in which three Triatomic form of oxygen in which three

atoms of oxygen are bondedatoms of oxygen are bonded Strong oxidant and chemically reacts Strong oxidant and chemically reacts

with many materials in the atmospherewith many materials in the atmosphere In the lower atmosphere, ozone is a In the lower atmosphere, ozone is a

pollutantpollutant Highest concentration of ozone in the Highest concentration of ozone in the

stratospherestratosphere

Measurement of Measurement of Stratospheric OzoneStratospheric Ozone First measured in 1920s using Dobson First measured in 1920s using Dobson

ultraviolet spectrometer.ultraviolet spectrometer. Dobson unit (DU) - 1DU = 1 ppb ODobson unit (DU) - 1DU = 1 ppb O33

Now have measurements from all over the Now have measurements from all over the world for 30 yearsworld for 30 years

Ground based measurements first Ground based measurements first identified ozone depletion over the identified ozone depletion over the AntarcticAntarctic Concentrations have been decreasing since Concentrations have been decreasing since

the mid-1970sthe mid-1970s ““Ozone hole”Ozone hole”

Ozone Depletion and CFCsOzone Depletion and CFCs

Hypothesis that ozone in the Hypothesis that ozone in the stratosphere is being depleted by stratosphere is being depleted by CFCsCFCs Based on physical and chemical Based on physical and chemical

properties of CFCs and knowledge properties of CFCs and knowledge about atmospheric conditionsabout atmospheric conditions

Vigorously debated by scientists, Vigorously debated by scientists, companies producing CFCs, and other companies producing CFCs, and other interested partiesinterested parties

Ozone Depletion and CFCsOzone Depletion and CFCs

The major features of the hypothesis:The major features of the hypothesis: CFCs emitted in the lower atmosphere CFCs emitted in the lower atmosphere

are extremely stable and therefore have are extremely stable and therefore have a very long residence time (about 100 a very long residence time (about 100 years)years)

CFCs eventually wander upward and CFCs eventually wander upward and enter the stratosphereenter the stratosphere

Once above the stratospheric ozone, Once above the stratospheric ozone, they may be destroyed by UV radiation, they may be destroyed by UV radiation, releasing chlorine, a highly reactive atomreleasing chlorine, a highly reactive atom

Ozone Depletion and CFCsOzone Depletion and CFCs

The chlorine released then depletes the The chlorine released then depletes the ozoneozone

Depletion increases the amount of UVB Depletion increases the amount of UVB radiation that reaches Earth’s surfaceradiation that reaches Earth’s surface

UVB is a cause of human skin cancers UVB is a cause of human skin cancers and is also thought to be harmful to the and is also thought to be harmful to the human immune systemhuman immune system

Emissions and Uses of Emissions and Uses of Ozone Depleting ChemicalsOzone Depleting Chemicals CFCs have been usedCFCs have been used

As aerosol propellants in spray cansAs aerosol propellants in spray cans Working gas in refrigeration and ACWorking gas in refrigeration and AC Production of StyrofoamProduction of Styrofoam

No longer used in spray cans but use No longer used in spray cans but use has increased in refrigerantshas increased in refrigerants

Simplified Stratospheric Simplified Stratospheric Chlorine ChemistryChlorine Chemistry CFCs are CFCs are

transparent to sunlight,transparent to sunlight, essentially insolubleessentially insoluble Non-reactive in the oxygen-rich lower Non-reactive in the oxygen-rich lower

atmosphereatmosphere When CFCs reach the stratosphere, When CFCs reach the stratosphere,

reactions do occurreactions do occur UVC splits up the CFC releasing chlorine, UVC splits up the CFC releasing chlorine,

the following two reactions can take place:the following two reactions can take place:Cl + O3 Cl + O3 →→ ClO + O2 ClO + O2ClO + O ClO + O →→ Cl + O2 Cl + O2

Simplified Stratospheric Simplified Stratospheric Chlorine ChemistryChlorine Chemistry This series of reactions is what is This series of reactions is what is

known as a catalytic chain reactionknown as a catalytic chain reaction Chlorine is not removedChlorine is not removed Reappears in the second reactionReappears in the second reaction Repeated over and overRepeated over and over

Process considerably more complexProcess considerably more complex Chain can be interrupted and Cl Chain can be interrupted and Cl

stored in other reactions stored in other reactions

The Antarctic Ozone HoleThe Antarctic Ozone Hole

Since 1958 ozone depletion has been Since 1958 ozone depletion has been observed in the Antarctic every observed in the Antarctic every October.October. Thickness decreasing and geographic Thickness decreasing and geographic

area increasingarea increasing Polar Stratospheric CloudsPolar Stratospheric Clouds

Form during the polar winter (polar night)Form during the polar winter (polar night) Air circulates about the pole in Antarctic Air circulates about the pole in Antarctic

polar vortex. polar vortex. Forms as the isolated air mass cools, Forms as the isolated air mass cools,

condenses, and descends.condenses, and descends.

An Arctic Ozone Hole?An Arctic Ozone Hole?

Polar vortex also forms over the Polar vortex also forms over the North Pole North Pole Weaker and does not last as long as Weaker and does not last as long as

AntarcticAntarctic Ozone depletion does occur at the NPOzone depletion does occur at the NP Major concern is ozone-deficient air Major concern is ozone-deficient air

moving southward over population moving southward over population centers.centers.

Environmental EffectsEnvironmental Effects

Several serious potential Several serious potential environmental effectsenvironmental effects Damage to food chain on land and in Damage to food chain on land and in

oceans (loss of primary production )oceans (loss of primary production ) Damage to human health (skin Damage to human health (skin

cancers, cataracts, and suppression cancers, cataracts, and suppression of immune system)of immune system)

UV Index measure of UV radiation on a UV Index measure of UV radiation on a given daygiven day

Environmental EffectsEnvironmental Effects

Reduce the risk of skin cancer and other Reduce the risk of skin cancer and other skin damage from UV exposure by:skin damage from UV exposure by: Limit exposure to the sun between the hours Limit exposure to the sun between the hours

of 10 A.M.and 4 P.M. of 10 A.M.and 4 P.M. Use a sunscreen with an SPF of at least 30Use a sunscreen with an SPF of at least 30 Wear a wide-brimmed hat and, where possible, Wear a wide-brimmed hat and, where possible,

tightly woven full-length clothingtightly woven full-length clothing Wear UV-protective sunglassesWear UV-protective sunglasses Avoid tanning salons and sunlampsAvoid tanning salons and sunlamps Consult the UV Index before going outConsult the UV Index before going out

Future of Ozone DepletionFuture of Ozone Depletion

The Montreal ProtocolThe Montreal Protocol Outlined a plan for the eventual Outlined a plan for the eventual

reduction of global emissions of CFCs to reduction of global emissions of CFCs to 50% of 1986 emissions50% of 1986 emissions

Elimination of the production of CFCs by Elimination of the production of CFCs by 19991999

Assessment of the protocol suggest that Assessment of the protocol suggest that CFCs will return to pre-1980 levels by CFCs will return to pre-1980 levels by 20502050

Future of Ozone DepletionFuture of Ozone Depletion Substitutes for CFCsSubstitutes for CFCs

Hydrofluorocarbons (HFCs) Hydrofluorocarbons (HFCs) Do not contain chlorineDo not contain chlorine Fluorine atoms participate in reactions Fluorine atoms participate in reactions

similar to those of chlorine - 1,000 times similar to those of chlorine - 1,000 times less efficient in those reactionsless efficient in those reactions

Hydrochlorofluorocarbons (HCFCs). Hydrochlorofluorocarbons (HCFCs). Contain an atom of hydrogen in place of Contain an atom of hydrogen in place of

one chlorine atom one chlorine atom Can be broken down in the lower Can be broken down in the lower

atmosphereatmosphere Still causes ozone depletion if they do reach Still causes ozone depletion if they do reach

the stratosphere before being broken downthe stratosphere before being broken down

Sources of Indoor Air Sources of Indoor Air PollutionPollution Secondhand smokeSecondhand smoke

Most hazardous common indoor air Most hazardous common indoor air pollutantpollutant

Legionella pneumophilaLegionella pneumophila Bacterium that causes a type of Bacterium that causes a type of

pneumonia called Legionnaires’ pneumonia called Legionnaires’ disease when inhaleddisease when inhaled

Some molds (fungal growths) in Some molds (fungal growths) in buildings release toxic sporesbuildings release toxic spores Cause chronic inflammation and Cause chronic inflammation and

scarring of lungsscarring of lungs

Sources of Indoor Air Sources of Indoor Air PollutionPollution Radon gas Radon gas

Seeps up naturally from soils and rocks below Seeps up naturally from soils and rocks below buildings buildings

Thought to be the second most common cause Thought to be the second most common cause of lung cancerof lung cancer

Pesticides Pesticides Deliberately or inadvertently applied in Deliberately or inadvertently applied in

buildings to control pestbuildings to control pest Toxic to people as wellToxic to people as well

Some varieties of asbestosSome varieties of asbestos Known to cause a particular type of lung Known to cause a particular type of lung

cancercancer

Sources of Indoor Air Sources of Indoor Air PollutionPollution Formaldehyde Formaldehyde

A VOC, used in many materials found in A VOC, used in many materials found in homes and offices homes and offices

Dust mites and pollen Dust mites and pollen Irritate the respiratory system, nose, eyes, Irritate the respiratory system, nose, eyes,

and skin of people who are sensitive to and skin of people who are sensitive to themthem

Sources of Indoor Air Sources of Indoor Air PollutionPollution Common indoor air pollutants are Common indoor air pollutants are

often highly concentrated compared often highly concentrated compared with outdoor levels with outdoor levels Many potential indoor sources of Many potential indoor sources of

pollutants. pollutants. Effectiveness of the steps we have Effectiveness of the steps we have

taken to conserve energy in buildings taken to conserve energy in buildings has led to the trapping of pollutants has led to the trapping of pollutants insideinside

Pathways, Processes, and Pathways, Processes, and Driving ForcesDriving Forces Many air pollutants originate within Many air pollutants originate within

buildings and may be concentrated buildings and may be concentrated there because of lack of proper there because of lack of proper ventilationventilation

Other air pollutants may enter by Other air pollutants may enter by infiltration,infiltration, Through cracks and other openings in Through cracks and other openings in

the foundations and walls the foundations and walls Or by way of ventilation systemsOr by way of ventilation systems

Pathways, Processes, and Pathways, Processes, and Driving ForcesDriving Forces Both natural and human processes Both natural and human processes

create differential pressures that create differential pressures that move air and contaminants from one move air and contaminants from one area to anotherarea to another Areas of high pressure may develop on Areas of high pressure may develop on

the windward side of a building, drawing the windward side of a building, drawing air inair in

Pressure is lower on the leeward, or Pressure is lower on the leeward, or protected, sideprotected, side

Pathways, Processes, and Pathways, Processes, and Driving ForcesDriving Forces

A chimney effect (or stack effect) A chimney effect (or stack effect) Occurs when there is a temperature Occurs when there is a temperature

differential between the indoor and differential between the indoor and outdoor environmentsoutdoor environments

Warmer air rises in the building to the Warmer air rises in the building to the upper levels, it is replaced in the lower upper levels, it is replaced in the lower portion of the building by outdoor airportion of the building by outdoor air

Secondhand smoke, may also be drawn Secondhand smoke, may also be drawn into a building by the chimney effect.into a building by the chimney effect.

Heating, Ventilation, and Air-Heating, Ventilation, and Air-Conditioning SystemsConditioning Systems

Systems are designed to provide a Systems are designed to provide a comfortable indoor environment for peoplecomfortable indoor environment for people

Design depends on a number of variablesDesign depends on a number of variables Including the activity of people in the building, Including the activity of people in the building,

air temperature and humidity, and air quality. air temperature and humidity, and air quality. If designed correctly, the system willIf designed correctly, the system will

Provide thermal comfort for people inhabiting Provide thermal comfort for people inhabiting the buildingthe building

Provide the necessary ventilation (utilizing Provide the necessary ventilation (utilizing outdoor air)outdoor air)

Remove common air pollutants via exhaust Remove common air pollutants via exhaust fans and filtersfans and filters

Environmental Tobacco Environmental Tobacco SmokeSmoke Environmental tobacco smoke (ETS)Environmental tobacco smoke (ETS)

Secondhand smokeSecondhand smoke Comes from two sources: Comes from two sources:

smoke exhaled by smokers smoke exhaled by smokers smoke emitted from burning tobacco in smoke emitted from burning tobacco in

cigarettes, cigars, or pipes. cigarettes, cigars, or pipes. People who are exposed to ETS are People who are exposed to ETS are

referred to as passive smokers.referred to as passive smokers.

Environmental Tobacco Environmental Tobacco SmokeSmoke

It is hazardous for the following reasons:It is hazardous for the following reasons: Tobacco smoke contains several thousand Tobacco smoke contains several thousand

chemicals, many of which are irritants. chemicals, many of which are irritants. Studies of nonsmoking workers exposed to ETS Studies of nonsmoking workers exposed to ETS

found that they have reduced airway found that they have reduced airway functions, suffer more illnesses, and lose more functions, suffer more illnesses, and lose more work time than those not exposed to ETSwork time than those not exposed to ETS

3,000 deaths from lung cancer and 40,000 3,000 deaths from lung cancer and 40,000 deaths from heart disease a year are thought deaths from heart disease a year are thought to be associated with ETS (in US0to be associated with ETS (in US0

Radon GasRadon Gas Radon is a naturally occurring Radon is a naturally occurring

radioactive gas radioactive gas Colorless, odorless, and tasteless. Colorless, odorless, and tasteless. Radioactive decay chain from Radioactive decay chain from

radiogenic uranium to stable lead radiogenic uranium to stable lead Radon-222 has a half-life of 3.8 days, is Radon-222 has a half-life of 3.8 days, is

the product of radioactive decay of the product of radioactive decay of radium-226. radium-226.

Radon decays with emission of an alpha Radon decays with emission of an alpha particle to polonium-218, which has a particle to polonium-218, which has a half-life of ~ 3 minuteshalf-life of ~ 3 minutes

Geology and Radon GasGeology and Radon Gas

The concentration of radon gas can The concentration of radon gas can enter our dwellings depends on enter our dwellings depends on concentration of radon in the rocks concentration of radon in the rocks and soil and soil Some regions in the United States Some regions in the United States

contain bedrock with an above-average contain bedrock with an above-average natural concentration of uraniumnatural concentration of uranium

How Does Radon Gas Enter How Does Radon Gas Enter Building?Building?

Three main ways:Three main ways:1.1. Migration from soil and rock into Migration from soil and rock into

basements and lower floorsbasements and lower floors

2.2. Dissolved in groundwater, it is pumped Dissolved in groundwater, it is pumped into wells and then into homesinto wells and then into homes

3.3. Radon-contaminated materials, such Radon-contaminated materials, such as building blocks, are used in as building blocks, are used in constructionconstruction

Sick BuildingsSick Buildings

There are two types of sick buildings:There are two types of sick buildings: Buildings with identifiable problemsBuildings with identifiable problems

Occurrences of toxic molds or bacteria Occurrences of toxic molds or bacteria known to cause diseaseknown to cause disease

Diseases are known as building-related Diseases are known as building-related illnesses (BRI)illnesses (BRI)

Buildings with sick building syndrome Buildings with sick building syndrome (SBS)(SBS)

Symptoms people report cannot be traced Symptoms people report cannot be traced to any one known causeto any one known cause

Sick BuildingsSick Buildings

When the cause is not detected. A number When the cause is not detected. A number of things may be happening:of things may be happening: The complaints result from the combined The complaints result from the combined

effects of a number of contaminants present in effects of a number of contaminants present in the buildingthe building

Environmental stress from another source is Environmental stress from another source is responsibleresponsible

Employment-related stress may be leading to Employment-related stress may be leading to the symptoms reportedthe symptoms reported

Pollutants or toxins may be present but not Pollutants or toxins may be present but not identifiedidentified

Control of Indoor Air Control of Indoor Air PollutionPollution Strong financial incentives to provide Strong financial incentives to provide

workers with a clean air environmentworkers with a clean air environment Meet minimum indoor air quality Meet minimum indoor air quality

standardsstandards Including increase in the inflow of fresh Including increase in the inflow of fresh

air through ventilationair through ventilation

Control of Indoor Air Control of Indoor Air PollutionPollution

One of the principal means for controlling One of the principal means for controlling quality is by dilutionquality is by dilution Fresh outdoor air mixed Fresh outdoor air mixed

Ventilating air-conditioning systemVentilating air-conditioning system Windows that can be openedWindows that can be opened

Various types of air-cleaning systems Various types of air-cleaning systems reduce potential pollutantsreduce potential pollutants Particles, vapors, and gasesParticles, vapors, and gases Can be installed as part of the heating, Can be installed as part of the heating,

ventilation, and AC system or as stand-alone ventilation, and AC system or as stand-alone appliancesappliances

Control of Indoor Air Control of Indoor Air PollutionPollution

Education also plays an important role Education also plays an important role May involve deciding not to install unvented or May involve deciding not to install unvented or

poorly vented appliances.poorly vented appliances. Educated people are more aware of their legal Educated people are more aware of their legal

rights with respect to product liability and rights with respect to product liability and safety. safety.

Education provides people with the information Education provides people with the information necessary to make decisions concerning necessary to make decisions concerning exposure, and strategies to avoid potentially exposure, and strategies to avoid potentially hazardous conditions in the home and hazardous conditions in the home and workplace.workplace.