Chapter 20Chapter 20Air PollutionAir Pollution

Overview of Chapter 20Overview of Chapter 20o Atmosphere as a ResourceAtmosphere as a Resourceo Types and Sources of Air PollutionTypes and Sources of Air Pollution

• Major Classes of Air PollutantsMajor Classes of Air Pollutants• Sources of Outdoor Air PollutantsSources of Outdoor Air Pollutants• Urban Air PollutionUrban Air Pollution

o Effects of Air PollutionEffects of Air Pollutiono Controlling Air Pollution in the USControlling Air Pollution in the US

Atmosphere as a ResourceAtmosphere as a Resourceo Atmospheric Atmospheric

CompositionComposition• Nitrogen 78.08%Nitrogen 78.08%• Oxygen 20.95%Oxygen 20.95%• Argon 0.93%Argon 0.93%• Carbon dioxide 0.04%Carbon dioxide 0.04%

o Ecosystem servicesEcosystem services• Blocks UV radiationBlocks UV radiation• Moderates the Moderates the

climateclimate• Redistributes water in Redistributes water in

the hydrologic cycle the hydrologic cycle

Types and Sources of Air Types and Sources of Air PollutionPollution

o Air PollutionAir Pollution• Chemicals added to the atmosphere by Chemicals added to the atmosphere by

natural events or human activities in high natural events or human activities in high enough concentrations to be harmful enough concentrations to be harmful

o Two categoriesTwo categories• Primary Air PollutantPrimary Air Pollutant

• Harmful substance that is emitted directly into Harmful substance that is emitted directly into the atmosphere the atmosphere

• Secondary Air PollutantSecondary Air Pollutant• Harmful substance formed in the atmosphere Harmful substance formed in the atmosphere

when a primary air pollutant reacts with when a primary air pollutant reacts with substances normally found in the atmosphere or substances normally found in the atmosphere or with other air pollutants with other air pollutants

Major Air PollutantsMajor Air Pollutants

Major Classes of Air PollutantsMajor Classes of Air Pollutantso Particulate MaterialParticulate Materialo Nitrogen OxidesNitrogen Oxideso Sulfur OxidesSulfur Oxideso Carbon OxidesCarbon Oxideso HydrocarbonsHydrocarbonso OzoneOzone

Particulate MaterialParticulate Materialo Thousands of different solid or liquid Thousands of different solid or liquid

particles suspended in airparticles suspended in air• Includes: soil particles, soot, lead, asbestos, Includes: soil particles, soot, lead, asbestos,

sea salt, and sulfuric acid droplets sea salt, and sulfuric acid droplets o Dangerous for 2 reasonsDangerous for 2 reasons

• May contain materials with toxic or May contain materials with toxic or carcinogenic effectscarcinogenic effects

• Extremely small particles can become Extremely small particles can become lodged in lungslodged in lungs

Nitrogen and Sulfur OxidesNitrogen and Sulfur Oxideso Nitrogen OxidesNitrogen Oxides

• Gases produced by the chemical Gases produced by the chemical interactions between atmospheric nitrogen interactions between atmospheric nitrogen and oxygen at high temperatureand oxygen at high temperature

• ProblemsProblems• Greenhouse gases Greenhouse gases • Cause difficulty breathingCause difficulty breathing

o Sulfur OxidesSulfur Oxides• Gases produced by the chemical Gases produced by the chemical

interactions between sulfur and oxygen interactions between sulfur and oxygen • Causes acid precipitationCauses acid precipitation

Carbon Oxides and Carbon Oxides and HydrocarbonsHydrocarbons

o Carbon OxidesCarbon Oxides• Gases carbon monoxide (CO) and carbon Gases carbon monoxide (CO) and carbon

dioxide (COdioxide (CO22) ) • Greenhouse gasesGreenhouse gases

o HydrocarbonsHydrocarbons• Diverse group of organic compounds that Diverse group of organic compounds that

contain only hydrogen and carbon (ex: CHcontain only hydrogen and carbon (ex: CH44- - methane)methane)

• Some are related to photochemical smog Some are related to photochemical smog and greenhouse gasesand greenhouse gases

OzoneOzoneo Tropospheric OzoneTropospheric Ozone

• Man- made pollutant in the lower atmosphereMan- made pollutant in the lower atmosphere• Secondary air pollutantSecondary air pollutant• Component of photochemical smogComponent of photochemical smog

o Stratospheric OzoneStratospheric Ozone• Essential component that screens out UV Essential component that screens out UV

radiation in the upper atmosphereradiation in the upper atmosphere• Man- made pollutants (ex: CFCs) can destroy Man- made pollutants (ex: CFCs) can destroy

itit

Sources of Outdoor Air PollutionSources of Outdoor Air Pollutiono Two main Two main

sourcessources• TransportationTransportation• IndustryIndustry

o Intentional forest Intentional forest fires is also highfires is also high

Urban Air PollutionUrban Air Pollutiono Photochemical Smog (ex: Los Angeles below)Photochemical Smog (ex: Los Angeles below)

• Brownish-orange haze formed by chemical reactions Brownish-orange haze formed by chemical reactions involving sunlight, nitrogen oxide, and hydrocarbons involving sunlight, nitrogen oxide, and hydrocarbons

Formation of Photochemical Formation of Photochemical SmogSmog

Sources of Smog in Los AngelesSources of Smog in Los Angeles

Case-In-Point Air Pollution in Beijing Case-In-Point Air Pollution in Beijing and Mexico Cityand Mexico City

o Beijing (left)Beijing (left)o Mexico City (above)Mexico City (above)

Effects of Air PollutionEffects of Air Pollutiono Low level exposureLow level exposure

• Irritates eyesIrritates eyes• Causes inflammation of respiratory tractCauses inflammation of respiratory tract

o Can develop into chronic respiratory Can develop into chronic respiratory diseasesdiseases

Health Effects of Air PollutionHealth Effects of Air Pollutiono Sulfur Dioxide and Particulate materialSulfur Dioxide and Particulate material

• Irritate respiratory tract and impair ability of Irritate respiratory tract and impair ability of lungs to exchange gaseslungs to exchange gases

o Nitrogen DioxidesNitrogen Dioxides• Causes airway restrictionCauses airway restriction

o Carbon monoxideCarbon monoxide• Binds with iron in blood hemoglobinBinds with iron in blood hemoglobin• Causes headache, fatigue, drowsiness, deathCauses headache, fatigue, drowsiness, death

o OzoneOzone• Causes burning eyes, coughing, and chest Causes burning eyes, coughing, and chest

discomfortdiscomfort

Children and Air PollutionChildren and Air Pollutiono Greater health threat to children than Greater health threat to children than

adultsadults• Air pollution can restrict lung developmentAir pollution can restrict lung development• Children breath more often than adultsChildren breath more often than adults

o Children who live in high ozone areas Children who live in high ozone areas are more likely to develop asthmaare more likely to develop asthma

Controlling Air Controlling Air Pollution in USPollution in US

o Smokestacks with Smokestacks with electrostatic precipitator electrostatic precipitator (right)(right)

Without Without Electrostatic Electrostatic precipitatorprecipitator

With Electrostatic With Electrostatic precipitatorprecipitator

Controlling Air Controlling Air Pollution in the USPollution in the US

o Smokestacks with Smokestacks with scrubbers (right)scrubbers (right)

o Particulate material Particulate material can also be controlled can also be controlled by proper excavating by proper excavating techniquestechniques

Controlling Air Pollution in the Controlling Air Pollution in the USUS

o Phase I Vapor Recovery System for Phase I Vapor Recovery System for gasolinegasoline

The Clean Air ActThe Clean Air Acto Authorizes EPA to Authorizes EPA to

set limits on amount set limits on amount of specific air of specific air pollutants permittedpollutants permitted

o Focuses on 6 Focuses on 6 pollutants:pollutants:• lead, particulate lead, particulate

matter, sulfur matter, sulfur dioxide, carbon dioxide, carbon monoxide, nitrogen monoxide, nitrogen oxides, and ozoneoxides, and ozone

o Act has led to Act has led to decreases!decreases!

Other Ways to Improve Air QualityOther Ways to Improve Air Quality

o Reduce sulfur content in gasoline from Reduce sulfur content in gasoline from its current average of 330 ppm to 30 its current average of 330 ppm to 30 ppmppm• Sulfur clogs catalytic convertersSulfur clogs catalytic converters

o Require federal emission standards for Require federal emission standards for all passenger vehiclesall passenger vehicles• Including SUVs, trucks and minivansIncluding SUVs, trucks and minivans

o Require emission testing for all vehiclesRequire emission testing for all vehicles• Including dieselIncluding diesel

Ozone Depletion in StratosphereOzone Depletion in Stratosphereo Ozone Protects earth from UV radiationOzone Protects earth from UV radiation

• Part of the electromagnetic spectrum with Part of the electromagnetic spectrum with wavelengths just shorter than visible light wavelengths just shorter than visible light

Ozone Depletion in StratosphereOzone Depletion in Stratosphereo Ozone thinning/holeOzone thinning/hole

• First identified in 1985 First identified in 1985 over Antarcticaover Antarctica

o Caused by Caused by • human-produced human-produced

bromine and chlorine bromine and chlorine containing chemicalscontaining chemicals

• Ex: CFCsEx: CFCs

Ozone Depletion in StratosphereOzone Depletion in Stratosphereo Hole over Antarctica requires two Hole over Antarctica requires two

conditions:conditions:• Sunlight just returning to polar regionSunlight just returning to polar region• Circumpolar vortex- a mass of cold air that Circumpolar vortex- a mass of cold air that

circulates around the southern polar region circulates around the southern polar region • Isolates it from the warmer air in the rest of the Isolates it from the warmer air in the rest of the

planet planet o Polar stratospheric clouds formPolar stratospheric clouds form

• Enables Cl and Br to destroy ozoneEnables Cl and Br to destroy ozone

Effects of Ozone DepletionEffects of Ozone Depletiono Higher levels of UV-Higher levels of UV-

radiation hitting the radiation hitting the earthearth• Eye cataractsEye cataracts• Skin cancer (right)Skin cancer (right)• Weakened immunityWeakened immunity

o May disrupt May disrupt ecosystemsecosystems

o May damage crops May damage crops and forestsand forests

Recovery of Ozone LayerRecovery of Ozone Layero Montreal Protocol (1987)Montreal Protocol (1987)

• Reduction of CFCsReduction of CFCs• Started using HCFCs (greenhouse gas)Started using HCFCs (greenhouse gas)

o Phase out of all ozone destroying Phase out of all ozone destroying chemicals is underway globallychemicals is underway globally

o Satellite pictures in 2000 indicated that Satellite pictures in 2000 indicated that ozone layer was recoveringozone layer was recovering

o Full recovery will not occur until 2050Full recovery will not occur until 2050

Acid DepositionAcid Depositiono Sulfur dioxide and nitrogen dioxide Sulfur dioxide and nitrogen dioxide

emissions react with water vapor in the emissions react with water vapor in the atmosphere and form acids that return atmosphere and form acids that return to the surface as either dry or wet to the surface as either dry or wet deposition deposition

o pH scalepH scale

How Acid Deposition DevelopsHow Acid Deposition Develops

Effects of Acid DepositionEffects of Acid Depositiono Declining Aquatic Declining Aquatic

Animal PopulationsAnimal Populationso Thin-shelled eggs Thin-shelled eggs

prevent bird prevent bird reproductionreproduction• Because calcium is Because calcium is

unavailable in acidic unavailable in acidic soilsoil

o Forest declineForest decline• Ex: Black forest in Ex: Black forest in

Germany (50% is Germany (50% is destroyed)destroyed)

Acid Deposition and Forest Acid Deposition and Forest DeclineDecline

Air Pollution Around the WorldAir Pollution Around the Worldo Air quality is deteriorating Air quality is deteriorating

rapidly in developing countriesrapidly in developing countrieso Shenyang, ChinaShenyang, China

• Residents only see sunlight a few Residents only see sunlight a few weeks each yearweeks each year

o Developing countries have Developing countries have older carsolder cars• Still use leaded gasolineStill use leaded gasoline

o 5 worst cities in world5 worst cities in world• Beijing, China; Mexico City, Beijing, China; Mexico City,

Mexico; Shanghai, China; Tehran, Mexico; Shanghai, China; Tehran, Iran; and Calcutta, India Iran; and Calcutta, India

Long Distance Transport of Air Long Distance Transport of Air PollutantsPollutants

Indoor Air Indoor Air PollutionPollution

o Pollutants can Pollutants can be 5-100X be 5-100X greater than greater than outdoorsoutdoors

o Most common:Most common:• Radon, cigarette Radon, cigarette

smoke, carbon smoke, carbon monoxide, monoxide, nitrogen dioxide, nitrogen dioxide, formaldehyde formaldehyde pesticides, lead, pesticides, lead, cleaning cleaning solvents, ozone, solvents, ozone, and asbestos and asbestos

Indoor Air Pollution - RadonIndoor Air Pollution - Radon