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Air Pollution
Review
• Name the bottom two layers of the atmosphere
– Troposphere, stratosphere
• 75-80% of atmosphere’s mass is in the __
– Troposphere
• Distinguish between good and bad ozone
– good: stratosphere, UV; bad: troposphere, lungs
Pollution
• The term “Smog” (smoke and fog) was first used
in 1905 to describe sulfur dioxide emission
Thorpe, Gary S., M.S., (2002). Barron’s How to prepare for the AP Environmental Science Advanced Placement Exam
• In 1952, severe pollution took the lives of 5000
people in London
• “It isn’t pollution that’s harming the
environment. It’s the impurities in our air and
water that are doing it.”
Former U.S. Vice President Dan Quayle
www.aqmd.gov/pubinfo/ 97annual.html
• Salt Lake City on a
smoggy day
Killer London smog, 1952
• December
• Very cold for several
days
• People burned more
coal
• Sulfur dioxide,
particulates
Deaths during ’52 killer smog
•
London smogs
•
• Picadilly circus,
London, winter,
1955
• NOON
1948: Air pollution inversion (cool air trapped by warm air above it keeps
pollution from dispersing) in Donora, Pennsylvania, kills 20 people and makes
40 percent of the town's 14,000 inhabitants ill.
1952: Sulfur-laden smog covers London and is responsible
for 4,000 deaths over a two-week period.
1967: Air Quality Control Act passed by Congress, setting timetables
for states to establish their own air quality standards.
1970: Congress passes the Clean Air Act, allowing the newly
created Environmental Protection Agency to set national air quality
standards. Also allowed states to establish their own stricter
standards, which California did.
Clean Air Act 1970
• Amendments to an earlier act
• ``To put the 1970 amendments in proper context, one needs to look
back at Congress' prior efforts to control air pollution, particularly the
Air Quality Act of 1967. That statute authorized the Secretary of
Health, Education, and Welfare (who then had chief responsibility for
federal environmental protection programs) to designate so-called air
quality regions throughout the country; the states were given primary
responsibility for adopting and enforcing pollution control standards
within those regions.
Some of us involved in the enactment of the 1967 statute had significant
doubts as to the viability of the regional approach to air pollution
control; after all, air contamination does not stop at neatly defined
regional boundaries. Nevertheless, Congress as a whole and American
industry were not yet convinced of the need for a national strategy for
pollution control; therefore, as a first step, the 1967 statute's regional
approach became the law of the land.’’
Paul Rogers, chair of House subcommittee on Health
and the environment
Debate on Clean Air Act, 1970
• During House floor debate:
– A representative quote a mayor: ``If you want
this town to grow, it has got to stink.’’
– A common view then
– Similar arguments continue to be made with
respect to efforts to control global warming
Clean Air Act
Requires EPA to set National Ambient Air Quality
Standards (NAAQS) for six ``criteria’’ air pollutants
• Ozone
• Sulfur dioxide
• Lead
• Carbon monoxide
• Nitrogen dioxide
• Particulate matter
Primary Pollutants
CO CO2
SO2 NO NO2
Secondary Pollutants
SO3
Most hydrocarbons
Most suspended
particles
Natural
Sources
Mobile
HNO3
H 2 O2
H2SO4
O3
PANs
–
Most NO3 and SO24 – salts
Stationary
Major Sources of Primary Pollutants
Stationary Sources
•
•
•
•
Combustion of fuels for power and heat – Power Plants
Other burning such as Wood & crop burning or forest fires
Industrial/ commercial processes
Solvents and aerosols
Mobile Sources
• Highway: cars, trucks, buses and motorcycles
• Off-highway: aircraft, boats, locomotives, farm equipment, RVs,
construction machinery, and lawn mowers
Natural air pollution
• Who said the following:
•
•
"I have flown twice over Mount St. Helens out on our west coast. I'm not a scientist
and I don't know the figures, but I have a suspicion that that one little mountain has
probably released more sulfur dioxide into the atmosphere of the world than has
been released in the last ten years of automobile driving or things of that kind that
people are so concerned about.’’
"Trees cause more pollution than automobiles do."
– RONALD REAGAN
Natural sources
• The facts:
– Volcanoes DO emit SO2.
Kilauea much worse than
Mount St Helens. MSH
probably emits less than cars;
Kilauea more (largest SO2
point-source emitter in the
US). Volcanoes also put out
particles and can cause health
and climate effects
– Some air pollution does come
from trees, decay. Typically,
spread out and not a health
risk, unlike anthropogenic
sources
Wind, dust
particulates
Volcanoes
Particulates, SO2,
CO2
Forest fires
CO2, unburned
HC
Vegetation
VOCs, pollen
Ocean
salt
Human Impact on Atmosphere
• Burning Fossil Fuels
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• Using Nitrogen
fertilizers and burning
fossil fuels
• Refining petroleum
and burning fossil
fuels
• Manufacturing
www.dr4.cnrs.fr/gif-2000/ air/products.html
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Adds CO2 and O3 to troposphere
Global Warming
Altering Climates
Produces Acid Rain
Releases NO, NO2, N2O, and NH3 into
troposphere
Produces acid rain
Releases SO2 into troposphere
Releases toxic heavy metals (Pb, Cd,
and As) into troposphere
Criteria
Air
Pollutants
EPA uses six "criteria pollutants" as indicators of air quality
1.
2.
3.
4.
5.
6.
•
Nitrogen Dioxide: NO2
Ozone: ground level O3
Carbon monoxide: CO
Lead: Pb
Particulate Matter: PM10 (PM 2.5)
Sulfur Dioxide: SO2
Volatile Organic Compounds: (VOCs)
EPA established for each concentrations above which adverse
effects on health may occur
Nitrogen Dioxide (NO2)
• Properties: reddish brown gas, formed as fuel
burnt in car, strong oxidizing agent, forms
Nitric acid in air
• Effects: acid rain, lung and heart problems,
decreased visibility (yellow haze), suppresses
plant growth
• Sources: fossil fuels combustion, power
plants, forest fires, volcanoes, bacteria in soil
• Class: Nitrogen oxides (NOx)
• EPA Standard: 0.053 ppm
Mobile Source Emissions: Nitrogen
Oxides
Ozone (O3)
• Properties: colorless, unpleasant odor, major part
of photochemical smog
• Effects: lung irritant, damages plants, rubber,
fabric, eyes, 0.1 ppm can lower PSN by 50%,
• Sources: Created by sunlight acting on NOx and
VOC , photocopiers, cars, industry, gas vapors,
chemical solvents, incomplete fuel combustion
products
• Class: photochemical oxidants
Ozone (O3)
• 10,000 to 15,000 people in US admitted to
hospitals each year due to ozone-related illness
• Children more susceptible
– Airways narrower
– More time spent outdoors
Mobile Source Emissions:
Hydrocarbons – Precursors to
Ozone
Carbon Monoxide (CO)
• Properties: colorless, odorless, heavier than air,
0.0036% of atmosphere
• Effects: binds tighter to Hb than O2, mental
functions and visual acuity, even at low levels
• Sources: incomplete combustion of fossil fuels
60 - 95% from auto exhaust
• Class: carbon oxides (CO2, CO)
• EPA Standard: 9 ppm
• 5.5 billion tons enter atmosphere/year
Mobile Source
Emissions - CO
Lead (Pb)
• Properties: grayish metal
• Effects: accumulates in tissue; affects kidneys, liver
and nervous system (children most susceptible);
mental retardation; possible carcinogen; 20% of
inner city kids have [high]
• Sources: particulates, smelters, batteries
• Class: toxic or heavy metals
• EPA Standard: 1.5 ug/m3
• 2 million tons enter atmosphere/year
Suspended Particulate Matter (PM10)
•Properties: particles suspended in air (<10 um)
•Effects: lung damage, mutagenic, carcinogenic,
teratogenic
•Sources: burning coal or diesel, volcanoes,
factories, unpaved roads, plowing, lint, pollen,
spores, burning fields
•Class: SPM: dust, soot, asbestos, lead, PCBs,
dioxins, pesticides
•EPA Standard: 50 ug/m3 (annual mean)
Mobile Source Emissions: Fine Particulate
Matter (PM2.5)
Sulfur Dioxide (SO2)
• Properties: colorless gas with irritating odor
• Effects: produces acid rain (H2SO4), breathing
difficulties, eutrophication due to sulfate
formation, lichen and moss are indicators
• Sources: burning high sulfur coal or oil,
smelting or metals, paper manufacture
• Class: sulfur oxides
• EPA Standard: 0.3 ppm (annual mean)
• Combines with water and NH4 to increase soil
fertility
VOCs (Volatile Organic Compounds)
• Properties: organic compounds (hydrocarbons) that evaporate easily,
usually aromatic
• Effects: eye and respiratory irritants; carcinogenic; liver, CNS, or
kidney damage; damages plants; lowered visibility due to brown haze;
global warming
• Sources: vehicles (largest source), evaporation of solvents or fossil
fuels, aerosols, paint thinners, dry cleaning
• Class: HAPs (Hazardous Air Pollutants)
– Methane
– Benzene
– Chlorofluorocarbons (CFCs), etc.
• Concentrations indoors up to 1000x outdoors
• 600 million tons of CFCs
Temperature inversion
• Makes effects of air
pollutants worse
• Usually: sun warms air at
Earth’s surface, which
rises and mixes, dispersing
pollutants
• Sometimes: layer of warm
air above cooler, denser
air, which does not rise
and mix
• Ordinarily, warm air
rises, carrying
pollutants with it
• If colder air is under
warmer air, the air is
stable, and pollution
can be trapped
Another kind of
temperature inversion
• Air warms up by compression as it flows downslope. Forms a ``lid’’
over colder air. This type of inversion common in Denver, which is to
right of the mountains
Acid rain
• Sulfur dioxide and
nitrogen oxides react
in atmosphere 
acidic chemicals that
can travel long
distances and return to
earth
• Tall stacks reduce
local pollution, but
increase regional
Sudbury, Ont. superstack
•
•
SEE TEXTBOOK, P. 445
Note: coal-burning plants in AZ, plume to NE
Acid rain impacts
• Erode metal and stone
• Acidifies lakes,
leading to fish deaths
• Acidifies soil, leaching
plant nutrients
The future of acid rain
• For better
– Clean Air Act
amendments of 1990
led to reductions in
SO2 and Nox
– Cap-and-trade program
• For worse
– U.S. and China have
huge coal reserves
Smog
• Photochemical smog
– Air pollutants (VOCs, NOx) react under
influence of sunlight and heat
– Form: ground level ozone and other chemicals
that together = smog
• Industrial smog
– A mixture of sulfur dioxide, sulfuric acid and
particulates
– Often in winter, with coal burning (eg: London)
Industrial smog in China
• Bejing
• China is home to 20 of
the world’s top 30 most
smog-plagued cities
Factors influencing smog formation
• DECREASE
• Local climate: rain and
snow wash pollutants out;
dry areas more prone
• Winds: mix pollutants or
blow them away
• Salt spray from ocean: can
remove particulates
• INCREASE
• Tall buildings reduce
wind
• Hills and mountains
• High temperatures
Indoor air pollution
• Often: a GREATER
threat to health than
outdoor air pollution
• EPA studies:
– 11 common pollutants often
2-5x higher indoors
– May be higher in cars in
urban areas
– People spend more time
indoors
Indoor air pollution
• Biggest problems
– Formaldehyde: low levels emitted from many
household products
• Furniture, paneling and plywood, insulation
– Radon: natural radioactive gas found in soil
• Outdoors, disperses; indoors, may concentrate and
contribute to lung cancer
– Lead, asbestos, carbon monoxide, chloroform