Lecture 11 Air Pollution

8/10/2019 Lecture 11 Air Pollution

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Air & Noise Pollution


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At the end of this lecture students should be able to:

1. Describe the five-layered structure of the atmosphere and the

% composition of gases within it.

2. List and describe the six major types of air pollutants,

distinguishing between primary and secondary air pollutants.

3. Explain the occurrence of urban smog and the impact of

topography and climate on it.

4. List indoor sources of air pollution.5. Describe the effect of air pollution on the ecosystem through

acid deposition, global warming and ozone depletion.

6. Explain how air pollution can be mitigated.


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- thin, gaseous envelopeof airaround Earth

- we liveat the bottomof this sea of air


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The atmosphereis dividedinto the:


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-atmospheres inner layer

- contains mostof Earths air

- N2( 78%), O2 ( 21%), CO2 ( 0.04%)

- weatheroccurs here

- temperaturedropswith an increasein altitude


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- layer abovetroposphere

- temperature riseswith altitude

- our global sunscreen


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- one or more chemicalsin highenough concentrationsin the airto:

1) harmorganismsor materials

2) alter climate


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Excess heatand noiseare also considered formsof air pollution.

Such chemicalsor physicalconditions are called air pollutants.


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Primary Pollutant- chemical, that occurs in a harmful concentration, addeddirectlyto the airby natural events or human activities


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Secondary Pollutant- harmful chemical formedin atmosphere when a primary airpollutantreacts with the normal air componentsor with otherair pollutants

eg. ozone, sulphur trioxide


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1.Natural events(eg, volcanic eruptions, dust storms)

2. Human activities(eg, emissions from carsand smokestacks)


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1. Carbon Oxides- eg, CO & CO2

2. Sulfur Oxides

- eg, sulfur dioxide (SO2), sulfur trioxide (SO3)


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3. Nitrogen Oxides- eg, nitric oxide (NO), nitrogen dioxide (NO2), nitrous oxide

(N2O)


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4. Volatile Organic Compounds- eg, methane, propane, benzene, chlorofluorocarbons (CFCs)


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5. Suspended Particles- eg, solid particles (dust, asbestos, soot)

- eg, liquid droplets (pesticides, sulfuric acid)


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6. Photochemical Oxidants- eg, ozone, hydrogen peroxide

7. Radioactive Substances

- eg, radon-222, plutonium-239

8. Toxic Compounds

- eg, traceamounts of at least 600 toxicsubstances, 60ofthem are carcinogens

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Smog

- originallya combination of smoke& fog

- nowdescribes other mixturesin the atmosphere

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Industrial Smog

- consists mainlyof a mixtureof sulfur dioxide, suspendeddropletsof sulfuric acid and a variety of suspendedsolidparticles

- found in citiesthat burn large amounts of coaland heavyoilwhich contain sulfur impurities

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Photochemical Smog

- mixtureof primary& secondarypollutants

- formed when hydrocarbonsand nitrogen oxidesreact under the influence of sunlight. Dominated by ozone

- found in almost all modern cities


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*Areas with high average annual precipitation, help cleansetheair of pollutants.

*Windshelp sweep pollutantsaway and bring in fresh air.

*Hills& mountainsreducethe flowof airin valleysbelow andallow pollutant levelsto build upat ground level.

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*Buildingsin cities slow wind speed& reduce dilutionandremoval of pollutants.

*The processofhot air risingand cold air sinkingcausing

continual mixing ofair, helps keep pollutants from reachingdangerous levelsnear the ground.

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- also called thermal inversion

- layerof dense, cool airtrapped under a layerof stagnant, lessdense warm air

- in a prolonged inversion, air pollutionin the trapped layer maybuild upto harmful levels

- enhances harmful effectsof urban heat islandsand dust domes

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- build-up of heatin the atmosphere above an urban area

- heatis producedby the large concentrations of cars, buildings,factoriesand other heat-producing activities


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http://healthandenergy.com/images/mold_spore_with_single_hyphae.jpg


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1. Cigarette Smoke- causes heart disease, lung& other cancers, bronchitis,stroke

- avoidable

- most preventable major causeof deathand sufferingamong adults


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Normal Lung Smoke-Damaged

Lung

Happy Smoker?

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2. Radioactive radon-222 gas

- produced when underground uraniumin rockand soildecaysand enters homesthrough cracks, drainsand hollowconcrete blocks

- colourless, odourless, tasteless

- naturally occurring radioactive gas

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3. Asbestos

- sprayed on ceilingsand wallsfor soundproofing,fireproofingand insulation

- once used in brake linings

(replaced by aramid)

- can cause asbestiosis and cancers

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4. Formaldehyde- colourless, irritating gas

- found in fingernail hardener, plywood, particleboard,paneling, drapes, upholstery, and fiberboard

- used in countertops, kitchen cabinets& 90% of USfurniture

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- the fallingof acidsand acid-forming compoundsfrom theatmosphereto the earths surface

- commonly known as acid rain

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- refers onlyto wetdepositionof dropletsof acidsand acid-forming compounds

- natural precipitationis slightly acidic(pH 5.0-5.6)

- acid raincan have a pHof 4.3or 3(as acidic as vinegar)

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- contributes to human respiratory diseases

- damages foliageand weaken trees

- kills fishes (prevents eggs hatching below pH 5)

- damages statues, buildings, metals, & car finishes

- releases aluminium ionswhich damage tree roots

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- natural effectthat traps heatin the troposphere

- some of the heatflowing back toward spacefrom Earths surfaceis absorbed, by H2O vapour, CO2, O3and other gases, then

radiated backtoward Earths surface


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- gasesin the tropospherethat causethe greenhouse effect- include:

carbon dioxide

chlorofluorocarbons

ozone

methane

water vapour

nitrous oxide

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- warmingof atmospheredue to increasesin the concentrationsofone or more greenhouse gasesprimarily as a result of humanactivities, mainly:

burning of fossil fuelsuse of CFCs

agriculture

deforestation

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In recent decades certain greenhouse gases have increasedinconcentration:

carbon dioxide

methane

nitrous oxide

CFCs

CO2contributes to ~ 55%of global warming.


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- Global warming is expected to result in climate change. It ispossible that there will be:

- 2-3 degree centigrade rise in temperature by 2080

- Decreased rainfall between June and August

- Sea level rise 0.2-0.5 metres by 2090

- Increased frequency and intensity of hurricanes

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- Warmer winters may result in less tourists

- Climatic conditions may change faster than some speciescouldadapt resulting in extinction

- Food-growing areas may change

- It is estimated that a 2 degree centigrade rise in temperature willreduce output of some crops such as kidney beans by 14-20%.

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- There may be longer periods of drought

- Increased temperatures will cause coral bleaching

Rising sea levels may:

- flood coastal settlements- result in beach erosion

-raise the salinity of low lying areas reducing productivity

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- more frequentand fiercerhurricanes

- disastrous for economicand social systems

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- The ozone layer is a layer of gaseous ozonelocated in thestratosphere

- The stratosphere contains O3good ozone

- The ozone layer prevents99%of harmfulultravioletradiationfrom reaching Earths surface

- It is being depleted by CFCs, halonsand other chemicals

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O3s filtering action protects us from:

* increased sunburn

* skin& eyecancer

* cataracts

* damage to our immune system

* damageto aquaticand landorganisms

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- Chlorofluorocarbons

- used in air conditioners, refrigerators, aerosol spray cans,cleanersfor electronic parts, hospital sterilants, fumigants,

plastic foam

- ozone eaters

- halons

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- increased cases of cancer& cataracts

- suppression of human immune system

- lowers crop yield

- degradation of materials

- reduction in phytoplankton

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- any unwanted, disturbingor harmfulsoundthat impairsorinterfereswith hearing, causes stress, hampers concentrationand work efficiencyor causes accidents

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-permanent hearing loss-hypertension

-insomnia

-irritability

-migraine headaches

-muscle tension

-gastric (stress)ulcers

-psychological disorders (eg, increased aggression)

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-enforceair& noisepollution laws-use emission control devices

-banor limit smokingto well-ventilated areas

-tax each unitof pollution produced

-use office machinesin well-ventilated areas

-shift to less polluting energy sources

-increase intakeof outdoor air

car exhaust inspections

Lecture 11 Air Pollution

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