ATMOSPHERIC POLLUTIONChapter 211Donora Pennsylvania, Oct 26,1948

2Air-pollution essentials3Constituents of the atmosphereN278.08%

O2 20.95%

Ar 0.93%

CO2 0.03%

Water vapor 0 4%

40 trace gases (O3, He, H, NOx, SO2, Ne)

Aerosol, dust, C particles, pollen, sea salts, microorganisms

4Air pollutantsSubstances in the atmosphere that have harmful effects. Depends on:

Amount of pollutantAmount of spaceMechanism that removes the pollutant from air

5Atmospheric cleansingThree natural occurring cleansers:

Hydroxyl radical (OH)Sea saltsMicroorganisms6Atmospheric cleansing: hydroxyl radical (OH)

7Appearance of smogIndustrial smog: A combination of smoke and fogAn irritating grayish mixture of soot, sulfurous compounds and water vapor

8Appearance of smogPhotochemical smogBrownish irritating hazeProduced when several pollutants from automobile exhausts react with sunlight

9Temperature Inversions

10Impact of SmogLong term temperature inversions can produce a build up of pollutants to dangerous levels

Smog causes headaches, nausea, eye and throat irritation and aggravate preexisting respiratory conditions

Air pollution affects trees and plants

Accelerates metal corrosion and the deterioration of rubber, fabrics and other materials.

11Major air pollutants and their sources12Types of air pollutantsPrimary pollutantsCombustion of coal, gasoline, other liquid fuels and refuseCH4 + 2O2 CO2 + 2 H2OEvaporation and strong winds

Secondary pollutants

13Primary PollutantsSymbolSuspended particulate matterPMVolatile organic compoundsVOCCarbon monoxideCONitrogen oxideNOxSulfur oxideSOxLeadPbAir toxicsVariousRadonRnSecondary PollutantsSymbolOzoneO3Peroxyacetyl nitratesPAN57814U.S. emissions of five primary air pollutants (2001)

15Clean Air Act impacts

16How ozone and other photochemical oxidants form?In the absence of VOCs

NO2 NO +O

O + O2 O3

NO + O3 NO2 + O2

17How ozone and other photochemical oxidants form?With VOCs

NO2 NO +O

O + O2 O3

NO + VOCs PANs

VOCs + O Aldehydes, ketones

Accumulation of ozone, VOCs, aldehydes and ketones

18Acid deposition

Acid precipitationAny precipitation that is more acidic than usual

Acid depositionCombination of precipitation and dry particle fallout19Acids and basespH: concentration of hydrogen ions

Acid: any chemical that releases hydrogen ions when dissolved in waterHCl, H2SO4, HNO3, H2CO3

Base: any chemical that releases hydroxide ionsNaOH, Ca(OH)2, KOH, NH4OH

20Extent and potency of acid precipitationRainfall pH 5,6

CO2 + H2O H2CO3

Acid precipitation pH 5,5 or less

SO2 + OH- H2SO4NOx + OH- HNO321Natural vs anthropogenic sourcesAnthropogenic sourcesIndustryTransportationFossil fuel and Coal burning electric utility plantsNatural sourcesSulfur dioxidesVolcanoesSea sprayMicrobial processesNitrogen oxidesLightingBurning biomassMicrobial processes

22Impacts of air pollutantsHealth and Environment23

Effects on human healthChronic effects:Long term exposure to SO2 bronchitisInhalation of ozone inflammation / fibrosis of lungsCO reduced capacity of the blood to carry oxygen and heart diseaseNOx impairs lung function/ affects the immune systemParticulate matter respiratory and cardiovascular pathologies. Allergens and other compounds in polluted air AsthmaLead mental retardation, high blood pressure (banned on 1996)24Effects on human healthAcute effectsIn severe cases air pollution may cause deathAir pollution may increase pre-existing symptoms.

25Effects on human healthCarcinogenic effectsOne major source of carcinogens is diesel exhausts. SootBenzeneFound in motor fuels, manufacture of detergents, explosives and pharmaceuticals, tobacco smokeCauses leukemia and other blood disorders and damage to the immune system.

26Effects on the environmentCrop damage

Forest damage

27Effects on the environmentMaterials and aesthetics

Visibility

28Effects on the environmentAcid deposition in aquatic ecosystemsHigher organisms die offLeach aluminum and various heavy metals from the soil

29Buffering capacity of aquatic ecosystemsBuffer: a substance that, when present in a solution, has a large capacity to absorb hydrogen ions and thus maintain the pH at a relatively constant value.

30Bringing air pollution under control31Clean air act (1970)Law administered by the EPA

Foundation of U.S. air pollution control efforts

Calls for identifying the most widely spread pollutantsSetting ambient standardsEstablishing control methods and timetables to meet standards. 32National Ambient Air Quality Standards (NAAQS)Standards for primary pollutants known as criteria pollutants

Primary standard is based on the presumed highest level that can be tolerated by humans without noticeable ill effects minus a 10% to 50% margin of safety

Short term standards are set to protect against acute effects

Long term standards are set to protect against chronic effects. 33National ambient air quality standards for criteria pollutantsPollutantAveraging timePrimary StandardPM10 particulates1 year24 hours50 ug/m3150 ug/m3PM2,5 particulates1 year24 hours15 ug/m365 ug/m3Sulfur dioxide1 year24 hours0.03 ppm0.14 ppmCarbon monoxide8 hours1 hour9 ppm35 ppmNitrogen oxides1 year0.053 ppmOzone8 hours1 hour0.08 ppm0.12 ppmLead3 months1.5 mg/m334National Emission Standards for Hazardous Air Pollutants (NESHAPs)Issued for eight toxic substancesArsenicAsbestosBenzeneBerylliumCoke-oven emissionsMercuryRadionuclidesVinyl chloride

The clean air act of 1990 extended this section naming 188 toxic air pollutants for the agency to track and regulate.35

Control strategiesCommand and control

Industry was given regulations to achieve a set of limits on each pollutant

A local government agency would be in control

Difficult to implement

Total air pollutants were reduced by 48%36

Control strategiesReducing particulates

The CAA mandated a phase-out of open burning of refuse and required that particulates from industrial stacks be reduced to no visible emissions

To reduce PM industries were required to install filters, electrostatic precipitators and other devices.

In 1997 the EPA added a new ambient air quality standard for particulates (PM2.5)

1990 Clean Air Act Amendments (CAAA) target specific pollutants under the control of a State Implementation Plan (SIP). Polluters obtain a permit that identifies the type of pollutant released, quantities and steps taken to reduce pollution. Permit fees provide funds for States to use in their air-pollution control activities.

Under the CAAA, states that fail to attain the required levels must submit attainment plants based on reasonably available control technology (RACT) measures

37Limiting pollutants from motor vehiclesCAA mandated a 90% reduction of emissions by 1975

A new car emits today 75% less pollution that pre-1970 cars

38How are pollutants limited in motor vehicles?Reduction in the size of passenger vehiclesPollution control devicesCatalytic converter

39CAAA changes for motor vehiclesNew cars sold in 1994 and thereafter were required to emit 30% less VOCs and 60% less NOx that cars sold in 1990

Starting in 1992 in regions with continuing carbon monoxide problems, oxygen was to be added to gasoline

Initiate inspection and maintenance programs in metropolitan areas

40Managing ozoneThe best way to reduce ozone levels is to reduce the emissions of VOCsMotor Vehicles (50%)Point sources: industries (30%)Area sources: dry cleaners, print shops, household products (20%)

VOC emissions have declined 35%

A reduction of NOx levels should remove the ozone further.

41Controlling toxic chemicals in the airUnder the CAAA, 188 toxic pollutants were identified

EPA was in charge to identify sources and develop maximum achievable control technology (MACT) standards.Options for substituting nontoxic chemicalsGiving industry some flexibility to achieve goalsGiving the state and local authorities the responsibility of controlRequiring cleaner burning fuels in urban areas

42Coping with acid depositionPolitical developments

States where coal-burning power plants produced most of their electrical power blocked attempts to pass a legislation to take action on acid deposition

Other states, the scientific community and Canadas diplomacy put pressure toward a resolution.

43Coping with acid depositionPolitical developments

As a result the Title IV of the CAAA was passed

Mandates a reduction in both sulfur dioxide and nitrogen oxide levels

Provides emission allowances regulated by the EPA

44Coping with acid depositionAccomplishments of Title IV

Many utilities are switching to low sulfur coal

Many utilities are adding scrubbers (liquid filters)

Many utilities are trading their emission allowances

45Unresolved issues46

Cost vs benefitMeasures taken to reduce air pollution carry an economic costThe Office of Management and Budget (OMB) found that the yearly benefits of environmental regulations ranged from $121 to $193 billion, while the costs ranged from $37 to $43 billion

New source reviewCAA requires all power plants and other polluting industrial facilities built after 1970 to incorporate best available pollution control technology.New facilities and upgrades must obtain permits before construction through the New source review program.Routine maintenance is permitted with no new technology required.

47Clear skies actAddresses three major pollutants simultaneously: SO2, NOx and mercuryApplies a cap and trade strategy:Cut SO2 emissions to a cap of 3 million tonsNO x emissions to a cap of 1.7 million tonsMercury to a cap of 15 tonsProposes a complete phase out to be achieved by 2018

48Getting aroundHalf of the major air pollutants come from vehiclesRaising CAFE standards would help to address:Dependence on imported oil Health issues from smog and particulatesCarbon dioxide emissions and global climate changeAuto industry, fossil fuel industry and politicians continue to resist raising CAF mileage requirementsOptions considered to reduce automobile emissions includeEmission free vehicles: powered by electricityHybrid carsPartial zero-emission vehicle: uses super clean gasolineMass transit ridership

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