Chapter 17: Atmospheric Science and Air Pollution www.aw-bc.com/Withgott

Atmosphere

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 surrounds earth mostly of N
2
, O
2
, Ar today's altering molecules consist of CH
4
, O
3
, CO
2 made up of layers ozone layer www.aw-bc.com/Withgott

Other Atmospheric Properties
 atmospheric pressure
– force per unit of area that air exerts on the surface of Earth
– declines with altitude
 atmospheric humidity
– ratio of water vapor contained in a given volume of air in relation to it's maximum amount possible
– the more humidity the hotter it seems

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Seasons

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 determined by the positioning in relation to the sun atmosphere absorbs 70% of the energy the shorter the distance, the more intense the sun rays solar radiation intensity is lower at the poles and higher at the equator tilting of the planet causes the seasons to occur

Air Circulation
 known as convective circulation
 caused by differences in humidity and temperature
 warm air rises as it is less dense
 cold air descends becoming denser www.aw-bc.com/Withgott

Weather & Climate
 Weather specifies atmospheric conditions over short periods of time and related to relatively small areas
 Climate describes patterns of atmospheric conditions across large regions and over long periods of time

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Weather
 depends on the fronts
–
– cold → thunderstorms warm → light rain
 affected by the pressure systems
–
– high → fair to dry weather low → results in clouds and precipitation

Thermal Inversion
 cooler air appears under warmer air
 prevents normal convective circulation to occur
 pollution is trapped under the inversion layer creating health problems like asthma
–
– killer smog in London asthma in San Joaquin valley

Global Climate Patterns
 Hadley cells: between equator and 30 º
–
– heavy rain at the equator arid at 30º www.aw-bc.com/Withgott

Global Climate Patterns
 Ferrer cells and polar cells lift air creating rain at ~60 º www.aw-bc.com/Withgott

Wind Patterns
 caused by the interaction of Hadley and
Ferrer cells and Earth's rotation
 Coriolis effect : winds are curved www.aw-bc.com/Withgott

Outdoor Air Pollution
 air pollutants
– natural sources
– human made sources

Natural Pollutants

–
–
–
–
– we have no control, occur naturally volcano eruptions
 Mt. Pinatubo produces particles circle the globe and remain in suspension for months acid rain affect temperature

Natural Pollutants
 dust storms
Texas dust storm 1930's
Arthur Rothstein, photographer, April, 1936. (Library of Congress)
Dallas dust storm 2007 www.panoramio.com

Natural Pollutants
 Fires
– soot and gases
–
– fuel buildup
T slash-and-burn
– in tropics
El Ni ño www.gsfc.nasa.gov
TX
Gulf Coast
LA
2000

Human Created Outdoor Pollution
 primary pollutants
– emitted directly to the troposphere
–
– can be harmful to the environment can form chemicals harmful to the environment
 secondary pollutants
– react with constituents of the atmosphere

Clean Air Act
 1970
– set stricter standards for air quality
–
– imposed limits to emissions funds for pollution control research
 1990
– strengthen air quality standards
–
– emission trading program for sulphur dioxide other emission trading programs developed

EPA Standards
 carbon monoxide (CO)



 sulphur dioxide (SO
2
) nitrogen dioxide (NO
2
) tropospheric ozone (O
3
) particulate matter
 lead (Pb)

Carbon Monoxide
 colorless
 odorless
 incomplete combustion
 in the U.S. 78% of it comes from vehicles
 small concentrations can be lethal to most living organisms

Sulphur Dioxide
 colorless
 pungent odor
 power plants of coal
London 1952

 once in the atmosphere SO
2
SO
3 and later forming H
2
SO
4 reacts forming
H
2
SO
4 forms acid rain

www.epa.gov
Nitrogen Oxides
Los Angeles
 contributes to smog



NO
2 is foul smelling, redish brown gas
NO x cause acid rain product of combustion engines

 vehicles produce 50% of the U.S. NO
X electricity production and industry the rest

Ozone



 product of sunlight + heat + NO
X
+ carbon chemicals health risk because of its instability →
O
2
+ Oxygen ion oxygen ion can cause tissue damage tissue damage can cause respiratory problems www.epa.gov
Los Angeles

Particulate Matter
 particles suspended in air
–
– primary pollutants → dust and soot secondary pollutants → sulphates and nitrates
 can damage respiratory tissues
 wind-blown result of human activities

Lead

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
 particulate matter enters food chain can cause nervous system malfunction
–
– present in gasoline to improve performance industrialized nations phased out leaded gasoline industrial metal smelting is the problem now

VOCs
 volatile organic compounds
 hydrocarbons
– methane forms part of natural gas
– propane used as portable fuel
– butane used in portable lighters
– octane component of gasoline

Pollutants in the U.S.
 2006
 137 trillion tons
 EPA data www.epa.gov

Pollution Decreased since 1970
 emissions declined 53% since 1970
– cleaner burning vehicles
–
– catalytic converter clean coal technology
– baghouse filters
– electrostatic precipitators
– scrubbers
– phase-out of lead in gasoline www.aw-bc.com/Withgott

Toxic Pollutants


188 toxic pollutants identified by the Clean Air Act in
1990 effects on people
–
–
–
–
–
– cancer reproductive defects neurological problems developmental problems affect the immune system respiratory diseases

Policy: Bush Administration



 elimination of new source review of 1977
–
–
– new pollution targets retrofitting aging plants with new technologies industry protested: too costly
Bush Administration exempted older plants allowed installing only "the best available" technology IF they ever upgraded the plant
Clear Skies (stopped by the Senate in 2005)
– from command-and-control to a market-based cap-andtrade

Smog
 fogs polluted by smoke= smog
– industrial smog
– photochemical smog

Industrial smog





 gray-air smog coal or oil burning
CO, CO
2
, soot mercury and sulfur in the carbon sample sulfur reacts forming SO
2
– sulphuric acid
– ammonium sulphate
Problems today: China, India, Eastern Europe
London 1952

Photochemical smog




 requires light brown-air smog
–
–
– ozone
NO x
VOCs irritates eyes, nose, throat
Houston 2000 car inspections reduction of vehicles driven per day
–
– allow certain cars to drive certain days of the week promote mass transit

Problems at Rural Areas
 airborne pesticides
 industrial pollutants from cities, factories and power plants migrate
 methane from cattle (18%)
 feedlots

– CH
4
, dust, NH
4
, SO x can cause respiratory problems

China
Industrialization




 is worsen air quality caused by factories and power plants emissions are released with little effort to control pollution
China & India have 58% of premature deaths worldwide (WHO)
Asian brown cloud
–
– reduces sunlight decreases productivity

Synthetic Chemicals
 CFCs (chlorofluorocarbons)
Arctic hole
 affects the ozone layer
 creating the ozone hole in Antarctica
 increases UV radiation
 leads to more skin cancer
 ecological effects still unknown
 hole in the arctic

Montreal Protocol of 1987
 addressed ozone depletion
 180 nations agreed to cut CFCs production in half
 production and use has dropped by 95%
 alternative chemicals
 CFCs take very long to brake down
 www.epa.gov/cppd

Acid Deposition www.aw-bc.com/Withgott




 originates with the NO
– x and SO x forms of precipitation known as acid rain
– fog
– dry particles pollutants react with water, O
2
, oxidants produce compounds of low pH (acids) these are suspended in the troposphere before falling as rain can cause political bickering

Acid Rain

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
 alters soil composition because: leaches chemicals from the soil harming plants and soil organisms also mobilizes toxic chemicals converts them to soluble forms affects agriculture affect lakes and rivers
 causing high mortality in fishes and amphibians

Acid Rain
 erosion of buildings
 corrodes cars
 erosion of statues and obelisks www.aw-bc.com/Withgott
 has not been reduced as expected in 1990
 more reduction of sulphur oxides and nitrogen oxides need to occur

Indoor Air Pollution
 higher concentration of pollutants indoor than outdoor
 workplaces, schools, homes
 volatile chemicals in the air
– insecticides
– cleaning fluids
– plastics
– chemically treated wood

Other Sources
 wood burning
– chimneys
– cooking
 tobacco smoking
 radon www.aw-bc.com/Withgott

Indoor VOC Pollution
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 perfumes paints plastics oils/candles cleaning fluids adhesives (glues) pesticides and insecticides ink (fax, photocopiers, printers) color films

Living Organisms also Pollute
 dust mites
 animal dander
 mold
 bacteria
 THE END