Air PollutionAir Pollution

Chapter 19Chapter 19

Atmosphere QuizAtmosphere Quiz

• Name the five layers of the Name the five layers of the atmosphereatmosphere

• What are the four main gases What are the four main gases found in air other than water? found in air other than water?

• Name three primary air pollutantsName three primary air pollutants• Name three secondary air Name three secondary air

pollutantspollutants

Five layers of the Five layers of the atmosphereatmosphere

• Troposphere Troposphere – Densest, 11 miles thickDensest, 11 miles thick– Air cools with increased altitudeAir cools with increased altitude– Ozone is poisonous hereOzone is poisonous here– Planes fly herePlanes fly here– Weather occurs hereWeather occurs here

Five layers of the Five layers of the atmosphereatmosphere

• StratosphereStratosphere– From 11 miles to 30 miles up from From 11 miles to 30 miles up from

earthearth– Temperatures rise with increased Temperatures rise with increased

altitudealtitude– Contains ozone layer Contains ozone layer

Ozone layerOzone layer

• Blocks out 95% of UV radiationBlocks out 95% of UV radiation– Allows life to existAllows life to exist– Prevents sunburn/cancer of skinPrevents sunburn/cancer of skin– Prevents oxygen in troposphere from Prevents oxygen in troposphere from

converting into toxic ozoneconverting into toxic ozone

Five layers of the Five layers of the atmosphereatmosphere

• Mesosphere – middle layer, air Mesosphere – middle layer, air cools with increased altitudecools with increased altitude

• Thermosphere – air warms with Thermosphere – air warms with increased altitudeincreased altitude

• Exosphere – air cools with Exosphere – air cools with increased altitude, blends to spaceincreased altitude, blends to space

What is in airWhat is in air

• 78% nitrogen78% nitrogen• 21% oxygen21% oxygen• 1% argon1% argon• < .1% carbon dioxide< .1% carbon dioxide

What does our What does our atmosphere do?atmosphere do?

• Two main natural processesTwo main natural processes– Greenhouse effect – keeping the Greenhouse effect – keeping the

planet warm through absorbing long planet warm through absorbing long wave radiation from the planet (water, wave radiation from the planet (water, COCO22, CH, CH44))

– Ozone shield – blocking unwanted UV Ozone shield – blocking unwanted UV radiationradiation

Primary pollutantsPrimary pollutants

• CO – carbon monoxideCO – carbon monoxide

• COCO22 – carbon dioxide – carbon dioxide

• SOSO22 – sulfur dioxide – sulfur dioxide

• NO – Nitric oxideNO – Nitric oxide

• NONO22 – Nitrogen dioxide – Nitrogen dioxide

• HydrocarbonsHydrocarbons• particulatesparticulates

Primary pollutantsPrimary pollutants

• Can be natural (volcano) but most are Can be natural (volcano) but most are human releasedhuman released

• Cars, industrial plants and power plants Cars, industrial plants and power plants (especially coal) are main sources(especially coal) are main sources

• When primary pollutants mix in air some When primary pollutants mix in air some form new secondary pollutantsform new secondary pollutants

Secondary PollutantsSecondary Pollutants

• SOSO33 – sulfur trioxide – sulfur trioxide

• HNOHNO33 – nitric acid – nitric acid

• HH22SOSO44 – sulfuric acid – sulfuric acid

• HH22OO22 – hydrogen peroxide – hydrogen peroxide

• OO33 - ozone - ozone

• PANs – peroxyacyl nitratesPANs – peroxyacyl nitrates

Human impactHuman impact

• We are altering natural balance of We are altering natural balance of cycles in the atmospherecycles in the atmosphere– Add ¼ more carbon dioxide (global Add ¼ more carbon dioxide (global

warming)warming)– Burn fossil fuels and use fertilizers Burn fossil fuels and use fertilizers

releasing NOreleasing NOxx into the air creating into the air creating more acid rain (nitric acid)more acid rain (nitric acid)

– Add sulfur to air from burning coal and Add sulfur to air from burning coal and refining petroleum (sulfuric acid)refining petroleum (sulfuric acid)

That’s only the beginningThat’s only the beginning

• Heavy metalsHeavy metals– 2x the arsenic as nature releases2x the arsenic as nature releases– 7x the cadmium7x the cadmium– 17x the lead17x the lead

It is hard to judge the effect on It is hard to judge the effect on particulates, but we release large particulates, but we release large amounts of ash and dustamounts of ash and dust

Photochemical smogPhotochemical smog

• Brown smogBrown smog• Mostly Ozone, aldehydes, PANs and Mostly Ozone, aldehydes, PANs and

Nitric acid formed from NONitric acid formed from NOxx from from cars/factories and volatile organic cars/factories and volatile organic compounds (CH4, propane, compounds (CH4, propane, benzene, CFCs) mixing in the benzene, CFCs) mixing in the presence of sunlightpresence of sunlight

Smog chemistrySmog chemistry

• NN22 + O + O22 = 2NO (engine of car) = 2NO (engine of car)– Then in the airThen in the air

• 2NO + O2NO + O22 = 2NO = 2NO22 (brown haze) (brown haze)– Gives choking odorGives choking odor

• 3NO3NO22 + H + H22O = 2HNOO = 2HNO33 + NO + NO

– Produces acid rain and some NOProduces acid rain and some NO22 goes on goes on to react this wayto react this way

• NONO22 + UV = NO + O which then + UV = NO + O which then

• O + OO + O22 = O = O33 (ozone) (ozone)

More smogMore smog

• Collectively NO2, O3, and PANs are Collectively NO2, O3, and PANs are known as chemical oxidants known as chemical oxidants because they react easily with because they react easily with other compounds or in your lungsother compounds or in your lungs

• Very small (trace) amounts can Very small (trace) amounts can irritate respiratory tracts or irritate respiratory tracts or damage crops/vegetationdamage crops/vegetation

Industrial smogIndustrial smog

• Known as gray-air smogKnown as gray-air smog

• Mostly SOMostly SO22 and H and H22SOSO44 as well as as well as suspended particles (ash)suspended particles (ash)

• Mostly caused by burning coal, but Mostly caused by burning coal, but can be prevented with controls can be prevented with controls (scrubbers, etc.)(scrubbers, etc.)

When smog is a real When smog is a real problemproblem

• Thermal inversion – a layer of Thermal inversion – a layer of warm air sits on top of a cold layer warm air sits on top of a cold layer trapping pollutants that would trapping pollutants that would normally disperse. This causes air normally disperse. This causes air pollutants to rise to harmful or pollutants to rise to harmful or deadly levelsdeadly levels

Ughh!Ughh!

• Enough bad news for one day.Enough bad news for one day.

Industrial smogIndustrial smog

• C + OC + O22 = CO = CO22 and CO and soot and CO and soot

• S + OS + O22 = SO = SO22

• 2SO2SO22 + O + O22 = 2SO = 2SO33

• SOSO33 + H + H22O = HO = H22SOSO44

• HH22SOSO44 + 2NH + 2NH33 = (NH = (NH44))22SOSO44 (salt) + (salt) + soot give the gray colorsoot give the gray color

Acid depositionAcid deposition

• Acid rain – wet acidAcid rain – wet acid• Acid deposition – dry acid (solid or Acid deposition – dry acid (solid or

a gas)a gas)

• Natural rain is pH 5 – 5.6 (without Natural rain is pH 5 – 5.6 (without acid) COacid) CO22 is dissolved from air is dissolved from air forming weak carbonic acidforming weak carbonic acid

Who/Where is affected?Who/Where is affected?

• Areas that are downwind from Areas that are downwind from industrial or dense urban zones are industrial or dense urban zones are in greatest risk of damage due to in greatest risk of damage due to acid depositionacid deposition

• Vegetation and aquatic life receive Vegetation and aquatic life receive most of the damagemost of the damage

Acid protectionAcid protection

• Natural buffers in soil – Ca+ and Natural buffers in soil – Ca+ and Mg+ can react and neutralize Mg+ can react and neutralize acids.acids.

• Thin acidic soils offer no bufferingThin acidic soils offer no buffering

Acid productionAcid production

• Factories, power plants, smelters Factories, power plants, smelters and cars produce the most acidand cars produce the most acid

• Acid crosses large distances via the Acid crosses large distances via the wind and can still damage “clean” wind and can still damage “clean” nations/areasnations/areas

Acid associated problemsAcid associated problems

• Humans – respiratory (bronchitis Humans – respiratory (bronchitis and asthma)and asthma)

• Buildings – premature agingBuildings – premature aging• Trees – weakens leaves, disease Trees – weakens leaves, disease

pest can then kill treepest can then kill tree• Soil – release metals (toxic) like Soil – release metals (toxic) like

aluminum (3aluminum (3rdrd most abundant most abundant element in crust) which can kill fish element in crust) which can kill fish by producing excess mucusby producing excess mucus

Acid associated problems Acid associated problems continued…continued…

• Aquatic – release methylmercury Aquatic – release methylmercury from natural mercury which from natural mercury which accumulates to toxic levels in fishaccumulates to toxic levels in fish

Acid preventionAcid prevention

• Reduce energy useReduce energy use• Switch from coalSwitch from coal to cleaner energy to cleaner energy

sourcessources• Remove sulfur from coal before Remove sulfur from coal before

burningburning• Remove SORemove SO22, NO, NOxx and particulates and particulates

from smokestacks with scrubbersfrom smokestacks with scrubbers• Remove NORemove NO22 from car exhaust from car exhaust

More acid cleanupMore acid cleanup

• Limestone can be added to lakes to Limestone can be added to lakes to neutralize acid, but it is hard to neutralize acid, but it is hard to determine how much and liming determine how much and liming can kill some organismscan kill some organisms

Let’s step insideLet’s step inside

• Indoor air pollutionIndoor air pollution– Carbon monoxideCarbon monoxide– AsbestosAsbestos– Nitrogen oxideNitrogen oxide– Trichloroethane (aerosols, dry cleaning)Trichloroethane (aerosols, dry cleaning)– Chloroform (chlorine in hot water)Chloroform (chlorine in hot water)– Radon (gas from uranium-238)Radon (gas from uranium-238)– Tobacco smokeTobacco smoke– Formaldehyde – particle board, furnitureFormaldehyde – particle board, furniture– Styrene – carpet, plasticsStyrene – carpet, plastics

What does it doWhat does it do

• Smoke – cancer, asthma, bronchitusSmoke – cancer, asthma, bronchitus• CO – dizziness, headache, heart attackCO – dizziness, headache, heart attack• Pm10 – respiratory disease, cancerPm10 – respiratory disease, cancer• SOSO22 – restricted airway – restricted airway• NO – lung irritation, asthma, encourage NO – lung irritation, asthma, encourage

spread of cancerspread of cancer• VOCs (benzene and formaldehyde) and VOCs (benzene and formaldehyde) and

toxic particulates (lead, cadmium, PCB, toxic particulates (lead, cadmium, PCB, dioxins) – mutations, reproductive dioxins) – mutations, reproductive problemsproblems

Ozone hurts treesOzone hurts trees

• As well as harming humans in the As well as harming humans in the troposphere, ozone affects plants troposphere, ozone affects plants and trees and trees

• Damage to leaves through poresDamage to leaves through pores• Reduced wax coatingReduced wax coating• Reduced photosynthesisReduced photosynthesis• Reduced nutrient uptakeReduced nutrient uptake

Regulation/protectionRegulation/protection

• Clean air actClean air act– Sets nation limits for seven pollutants Sets nation limits for seven pollutants

– pm10, SO2, CO, Nox, O3, VOCs, and – pm10, SO2, CO, Nox, O3, VOCs, and leadlead

– Also prevents significant deterioration Also prevents significant deterioration in any areain any area

– EPA set levels for 302 individual EPA set levels for 302 individual compounds and 20 categories of toxic compounds and 20 categories of toxic compoundscompounds

Improving the LawsImproving the Laws

• Switch from cleanup to preventionSwitch from cleanup to prevention• Conservation/alternate energy Conservation/alternate energy

sources (no fossil fuels)sources (no fossil fuels)• Stricter emission standardsStricter emission standards• Eliminate trash incinerationEliminate trash incineration

Emission controls for Emission controls for smokestackssmokestacks

• Electrostatic precipitatorElectrostatic precipitator• Baghouse filter – good for pm10Baghouse filter – good for pm10• Cyclone separatorCyclone separator• Wet scrubberWet scrubber

• All collect toxic solids which then All collect toxic solids which then must be disposed of as hazardous must be disposed of as hazardous wastewaste

Reducing indoor air Reducing indoor air pollutionpollution

• Better ventingBetter venting• In developing countries – better In developing countries – better

stoves, no smoke in the housestoves, no smoke in the house• Use natural fibersUse natural fibers• Reduce use of household cleaners Reduce use of household cleaners

with harsh chemicalswith harsh chemicals• No dry cleaningNo dry cleaning