Unit 7: Chapter 18
Chapter 12 Reading QuizWhich layer of the atmosphere is closest
to earth? ThermosphereMesosphereTroposphereStratosphereHow are
primary pollutants and secondary pollutants related?Which of the
following is/are NOT common air pollutant(s)?CO2, SO2, O2, NO2, O3,
H2OA photochemical reaction is a chemical reaction activated by
_____________.What is the gas that constitutes the majority of
photochemical smog?Air & Air PollutionChapter 12The
AtmosphereLayers:TroposphereStratosphereMesosphereThermosphere
Temperature & Pressure relationships
This course will focus mostly on the 2 closest to earth (Trop
& Strat)p. 2783Troposphere1st layer of atmosphereHas 75% mass
of earths airConsists of 99% dry air (mostly N & O) Varying
amounts water vaporPressure decreases with altitudeExtends 11 miles
above sea level (as thick as an apples skin if the earth were an
apple)Thinner at the poles (~5 miles)
78% N, 21% OVapor varies (.01% at poles, 4% in tropics)Argon
1%CO2 .037%Trace amounts of others4Stratosphere2nd layer of
atmosphereContains much less matter than troposphere, but
composition is similarVolume of water vapor is less Volume of ozone
is much greaterOur health depends on having enough ozone in
stratosphere and little introposphere.
Extends 11-30 miles above sea level (~twice as thick as
troposphere)
1/1000 water vapor
Ozone = O3, produced when O2 reacts with UV sunlightglobal
sunscreen keeps out 95% of harmful radiation
5
Are we (humans) decreasing good ozone and increasing bad
ozone?
Bad nearby, good up highGRAPH P. 279 (top)6Air PollutionPresence
of one or more chemicals in the atmosphere in quantities and
duration that cause harm to humans, other forms of life, and
materials. Primary PollutantsEmitted directly into
troposphereNatural and anthropogenic sourcesnatural events: dust
storms, volcanic eruptions, firesanthropogenic: emissions from
cars, smokestacks in power plants & factoriesstationary vs.
mobileCan combine (with each other or other components of air) to
form secondary pollutantsNatural sources are usually spread out and
rarely reach harmful levels (except some major volcanoes)Most
ambient air pollution in urban areas is from the burning of fossil
fuels8Air Pollutants Commonly Found in Ambient AirCarbon
oxidesSulfur oxidesNitrogen oxidesVOCsSPMPhotochemical
oxidantsRadioactive substancesHAPs
p. 280Ambient = outdoor
CO, CO2SO2, SO3NO, NO2, N2O (NOX needed to form ozone limit NOX
= limit ozone)Volatile Organic Compounds = CH4, CFCs (precursor to
ozone limit VOCs = limit ozone)Suspended Particulate Matter = dust,
soot, lead, etc. (clog alveoli in lungs)O3Radon, plutoniumHazardous
Air Pollutants = carbon tetrachloride, etc.
9
Primary PollutantsStationaryMobileNaturalMost hydrocarbonsMost
suspendedparticlesSO2NONO2COCO2Secondary
PollutantsSO3HNO3H2SO4H2O2O3PANsMostNO3andSO42saltsSecondary
pollutants: ex- acid rain SO2/NOX combine with water vapor. Ex-
ozone P. 27910NAAQSGovernment mandated maximum allowable
atmospheric concentrations6 Criteria Air
PollutantsCONO2SO2Particulate matterO3LeadCongress directed the EPA
to establish National Ambient Air Quality Standards in most
developed countries there are standards like theseBUT in ING they
do not exist or are not enforcedThen, the mobile pollutant can blow
into an area with strict emissions laws
p. 281 (list of 6 criteria pollutants, sources, &
health/enviro effects)11Urban AreasCities normally have higher
levels of air pollution (compared with rural areas).Air pollution
is highly mobileCan spread via winds very easilyIndoor and outdoor
air pollution high-risk human health problems1.1 billion people
live in areas where air is unhealthy to breatheMostly cities &
developing countries
Indoor air pollution will go with risk/toxicology unit (next
unit)12Photochemical SmogMixture of primary and secondary
pollutants formed under the influence of sunlight. Dominated by
photochemical ozone. (O3)Highly reactiveHarms most living
organismsHuman sources: chemical rxn with VOCs & NOxemitted
mostly by cars/industryHealth effects: breathing problems,
coughing, ENT irritation, aggravates asthma/bronchitis/etc.More
than 100 chemicalsDiesel engines emit NOx14Photochemical
SmogFactors influencing ozone levels/PC smog:HeatHotter = Higher
levels of O3TrafficMore traffic (esp. stand still) = Higher levels
of O3SunlightClear days (few clouds) = Higher levels of O3Cities
with sunny, warm, dry climates and lots of motor vehiclesLA, U.S.;
Sydney, Asutralia; Mexico City, MexicoStand still traffic is the
worst because when a car emits the most/worst pollution when
idling. 15Industrial SmogConsists mostly of sulfur dioxide,
suspended droplets of sulfuric acid, and a variety of suspended
solid particles and droplets. Source: power plants/factories
burning large amounts of coal/heavy oil (high sulfur content)
Examples: London, England; Pittsburgh, U.S.Where is industrial smog
an issue?Industrialized urban areas of China, India, Ukraine
(anywhere large amount of coal are burned without sufficient
pollution control)Rarely a in developed countries (today)
More severe during the winter months 50+ yrs ago?
NOW, most coal/heavy oil is burned in factories/plants with
large boilers & reasonably good pollution control or tall
smokestacks-smokestacks: transfer pollutants to downwind areas not
the best solution-Boilers: scrubbers to reduce SO2 emissions;
catalysts to reduce NOx emissions
16Factors Influencing SmogLocal climate and topographyRain &
snowWindsHigh temperaturesHills & mountainsPopulation
densityUrban buildingsAmount of industryFuels used in industry,
heating, transportationRain and snow help cleanse air of
pollutantsWinds sweep pollutants away, dilute pollutants by mixing,
bring in fresh airHigh temps promote chemical reactions that lead
to PC smogHills and mountains reduce flow or air (esp in valleys) =
pollutants build up a ground level (REMOVES BENEFITS OF WINDS)Urban
buildings reduce flow or air/slow wind speed = reduce dilution and
removal of pollutants (REMOVES BENEFITS OF WINDS)
17Temperature Inversion/ Thermal InversionWhen a layer of dense,
cool air beneath can be trapped beneath a layer of less dense warm
air in an urban basin or valley. Prevents mixing/dispersion of
pollutantsSubsidence temperature inversionRadiation temperature
inversionAreas especially susceptible to prolonged temperature
inversions:Cities located in a valley OR with mountains on three
sides and an ocean on the fourthSubsidence = caving in or sinking
of an area of landSubsidence inversion = large mass of warm air
moves into a region at a high altitude/floats over mass of cold air
near ground
Radiation inversion = nighttime air near ground cools faster
than the air above it usually disappears as sun rises
Cities in valley: mountains block out sunlight needed to reverse
nightly radiation temperature inversionCities in valley: also hold
in pollutants as warm air sits on top, no where for cool air to
go
Ocean air/winds cool air near surface18Pollutantswarmaircool air
surface heated by sun warm air rises (incl. pollutants) cools off,
mixes with air of equal density & dispersescool airwarm air
(inversion layer) surface cools rapidly (night) a layer of warm air
overlays surface polluted surface air rises but cannot disperse
remains trapped19Acid Deposition: What is it?Acid Deposition is the
falling of acids and acid forming compounds from the atmosphere to
the earths surface. a.k.a. acid rain.Sources: SO2, NOx (in
emissions from coal-burning plants, mostly)Combine with water vapor
to produce acid rainnitric acid, sulfuric acid, sulfate/nitrate
saltsCan be wet, dry, or a mix
SO2/NOx are primary pollutants, acid deposition is secondary
Vapor or droplets formed, sulfate/nitrate salts are acid-forming
particles
Wet = rain, snow, fog Dry = acidic particles Mix = acid
depositionWer = takes about 4-14 days to fall (farther from source,
downwind) Dry = 2-3 days to fall (close to source)21Acid
Deposition: pHpH: measure of the concentration of hydrogen ions in
a solutionpH < 7 acidicpH = 7 neutralpH > 7 alkaline or
basicLower than 5.6 considered acid rain
Natural precipitation is slightly acidic: 5.0-5.6Typical rain in
the US is now about 10X more acidic: 4.3Can be as acidic as 2.3
(1000X more acidic than natural rainwater)22Acid Deposition:
Where?What areas are affected?Regional (as opposed to
global)Downwind coal burning power plants, factories, larger urban
areas with many motor vehicles.Plants/factories will use
smokestacks that reach above the inversion layer to release
emissionsReduces local air pollutionIncreases regional air
pollution23
Acid Deposition: Where?Many coal burning industries/factories in
Ohio Valley
p. 286 for world mapEastern US, Europe, S.E. China
MOBILE so can be transported to location where there is not
actually activity leading to acid rainEx: Southeastern Canada acid
deposition can be traced to emissions from Ohio Valley and vice
versaLICHEN ARTICLE at beginning of Ch. 12 (coal-burning facilities
in Thunder Bay, Canada harmed lichen on Isle Royale)24Acid
Deposition: EffectsEcological problems = medium risk Human problems
= high risk
Can cause serious and costly ecological and economic
effects25Acid Deposition: Ecological EffectsHow seriously
vegetation and aquatic life in lakes are affected depends mostly on
whether its soils are acidic or basicSome soils contain natural
buffers:Soils eroded from parent material with alkaline properties
(i.e. marble, limestone):Slightly basic and can (at least
partially) neutralize acid rain as it percolates through the soil
horizonsCan lose buffering capacity through prolonged acid rainIf
only thin, acidic soil:No buffering capacityBuffer or
neutralizer26Acid Deposition: Ecological EffectsTerrestrial:Hardest
hit areas - mountaintop forestsTend to have thin soils w/out much
buffering capacityExposed to acidic fog (high altitudes)Leach soil
of nutrients = difficult for plants to growTrees directly affected
damaged foliageInterferes with photosynthesisWater lossMakes trees
more susceptible to other stressesAnimal life affected cant get
food, lost habitat
Mountain top forests usually have lots of conifers, which have
acidic needles anyway
Other stresses: cold temperatures, diseases, insect attack,
drought, fungi, etc.
Promote growth of acid-loving mosses, which can kill trees and
outcompete endemic/healthy mosses
SEE FIGURE 12-11, P. 288
ALL OF THIS IN ADDITION TO HARMFUL EFFETS OF OZONE = bad news
bears27Acid Deposition: Ecological EffectsAquatic:Acidic runoff
lowers pH of lake/pondMost cannot tolerate lower than 5Acid shock
kills fishLoss of fish and other populationsEcosystem
collapseContaminate fish in some lakes with highly toxic methyl
mercury (emitted by coal burning plants)Organisms (including
humans) that eat the contaminated fish may experience negative
health effects.Neg. health effects: kidney failure, brain damage,
death
Some aquatic organisms more tolerant than others see p. 287
figure 12-10
Can add lime to neutralize acidic lakes, but not permanent (must
be done each year if the source of the problem is not addressed)
AND it can kill some species and is difficult to determine how
much/where to use
Add phosphate fertilizer to neutralize? Then what?
Eutrophication?
28Acid Deposition: Human EffectsHuman healthContributes to human
respiratory diseases (bronchitis/asthma)Can leach toxic chemicals
into drinking waterCan damage statues, buildings, metals, car
finishesDecreases visibilityLowers productivity in fisheries, farms
(due to weak soils and direct harm of foliage)Many of the same
effects as ozone29Acid Deposition: Reduction/PreventionPrevention
Solutions:Reducing energy useImproving energy
efficiencyCoal:Removing sulfur from coal before it is burned
ORBurning low sulfur coalInstalling scrubbers and catalysts in
boilers to reduce SO2 and NOxEven BETTER: Switching from coal to
Cleaner burning natural gas ORRenewable energy Tax emissionsONCE
AGAIN, the best solution is prevention as opposed to clean up
(least harmful to environment, and least costly $$)
Hard to motivate because often the effects are far from the
cause (air emissions extremely mobile via winds)Coal is a major
energy resource, especially for countries that have a lot on hand
(China, Russia, US)Expensive- especially on large scale for
industry/factories (removing sulfur, low-sulfur coal,
scrubbers/catalysts)30Preventing & ReducingAir
Pollution32LawClean Air Acts of 1970, 1977, & 1990Pollution
regulationsEPA established:National Ambient Air Quality Standards-
NAAQSCO, NO2, SO2, particulate matter, O3, leadnational maximum
emission standards for toxic air pollutants (known/suspected to
cause cancer and other adverse health effects)
33
34Law: Is it working?1970-1998: Criteria pollutant total
emissions declined even when population was increasingIncreasing
production & vehicular travel1978-1998: Lead down by 97%Get the
lead out lead banned in gasolineCO down 60%SO2 down 58%O3, SPM
down35Law: Is it working?1970-1998: NOx emissions increased
by11%World: 62 million people still live in areas where the air
still does not meet the primary standardsU.S.: about half our
population lives in an area with dangerously high smog levels
36Law: Improvements?Focus on pollution prevention (rather than
cleanup)Increase fuel efficiency standards- carsRegulate emissions
from 2-cycle enginesRequire stricter emission standards for fine
particulates
2-cycle = lawnmowers, leaf blowers, chain saws, marine engines
(boat, jet ski, etc.)1 hr. ride on jet ski air pollution > avg.
car in 1 yr. WHAT?! . And.. Oil spilled from marine engines = 15X
more/yr. Exxon Valdez37SO2 CreditsEmissions trading policy
Allowable under CAA 1990Buy & sell SO2 pollution rightsPlant
uses less than their allotted pollution rights allow?More emissions
in another facility, bank for future, or sell to another
plant/citizen/enviro. gp.Goal?Net reduction in SO2 pollution
Environmentalists want to gradually reduce the number of credits
allotted annuallyBad? Allows utilities to keep on emitting
unacceptable levels, buy their way outCHEATING- relies on
self-reporting. Need an auditing system
These types of programs suggested for NOx, particulates, and
VOCs38Reducing Outdoor Air PollutionPreventionSO2, NOx,
particulates:Burn low-sulfur coalRemove sulfur from coalConvert
coal to a liquid or gaseous fuelShift to less polluting
fuelsCleanup:Disperse emissions above thermal layer (tall
smokestacks)Remove pollutants after combustionSee p. 296 Figure
12-18Tax units of pollutionSAME as reducing acid deposition because
(some of) these primary pollutants lead to acid rain
Doing these things will also limit O3 since NOx O3
THIS IS FOR STATIONARY SOURCES
39Reducing Outdoor Air PollutionPreventionmobile
emissions:Increase use of mass transit, bicycles, walkingLess
polluting & more effifient fuels/enginesGet old cars off the
roadRestrict driving or tax emissionsCleanupEmission control
devicesEx: NOx from diesel engines
Some prevention methods are expensive = hard to motivate
individuals/industry to participate
THIS IS FOR MOBILE SOURCES
40
SCR technology is one of the most cost-effective and
fuel-efficient technologies available to help reduce diesel engine
emissions. All heavy-duty diesel truck engines produced after
January 1, 2010 must meet the new EPA standards, among the most
stringent in the world, reducing particulate matter (PM) and
nitrogen oxides (NOx) to near zero levels. SCR can reduce NOx
emissions up to 90 percent while simultaneously reducing HC and CO
emissions by 50-90 percent, and PM emissions by 30-50 percent. SCR
systems can also be combined with a diesel particulate filter to
achieve even greater emission reductions for PM. In the commercial
trucking industry, some SCR-equipped truck operators are reporting
fuel economy gains of 3-5 percent. Additionally, off-road
equipment, including construction and agricultural equipment, must
meet EPA's Tier 4 emissions standards requiring similar reductions
in NOx, PM and other pollutants. 41Protecting the AtmosphereFocus
more on pollution preventionIntegrate air-pollution,
water-pollution, energy, and land-use policiesRegulating air
quality for larger regionsImprove energy efficiencyLess FF, more
renewable energySlowing population growthDistribute cheap and
efficient or solar cookstoves in developing countriesSome places
have seen great improvements: Toyko, W EuropeOther are just as
bad/worse: urbanized areas of developing countries
air shed- so its harder to just pump your pollution somewhere
else
42Indoor Air PollutionChapter 12, Sections 5 & 6Types and
Sources of Indoor Air PollutionHigher in homes and commercial
building than outdoors, as much as 70 times.Pollution levels inside
cars in traffic clogged urban areas can be up to 18 times higher.At
greater risks are smokers, infants, children under age 5, the old,
the sick, pregnant people, people with heart problem.
ContinuedPollutants found in building to be: dizziness,
headaches, coughing, sneezing, nausea, burning eyes, chronic
fatigue, and flu like symptoms, known as sick building syndrome.New
ones are more commonly sick than old ones because of reduced air
exchange.ContinuedCan be mineral fibers falling from ceiling tiles
and blowing in from the lining of the air conditioning
ducts.Cigarette smoke, formaldehyde, asbestos, and radioactive
radon are the most dangerous.
How human health is harmed?Lung cancerAsthmaChronic bronchitis
Emphysema
What pollutants cause these problems?Suspended particulate
matter: asthma Fine particlesUltrafine particlesSulfur dioxide:
asthma/ bronchitisNitrogen oxides: asthma/ bronchitisVolatile
organic compounds: cancer
Humans Die from PollutionAnnually, U.S. estimates 65,000-200,000
premature deaths from outdoor pollutionIndoor pollution included:
150,000-350,000 premature deathsWorldwide: 2.7 million premature
deathsMillions more face illness
Reducing Indoor Air PollutantsUsing simple stoves that burn more
efficiently (reduces deforestation)Using simple solar
cookersBreathing wallAbsorbs indoor dirty airExhales clean air