air pollution - polk county school district · 2018-08-30 · oozone rhs environmental science 18 ....
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Air Pollution Environmental Science
Mr. Moss
RHS
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Definition • Air Pollution – is the presence of chemicals in the
troposphere in concentrations high enough to harm
organisms, ecosystems, or materials, and high
enough to alter climate.
• Can range from annoying to lethal.
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Sources • Come from both natural and human sources.
• Natural sources: o Dust (windstorms)
o Wildfires
o Volcanic eruptions
o Volatile Organic Chemicals (VOC’s)
• Released from some plants
• Human sources: o Most are in industrialized and urban areas.
• High concentration of people, factories, and cars.
o Most come from the burning of fossil fuels in
• Power plants and factories (stationary sources)
• Motor vehicles (mobile sources).
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Refining the Definition • Pollution is something produced by humans that
interferes with our well-being.
• Although natural source fit our definition, they are
generally not controlled by humans. We will focus
on those factors that are controlled by humans.
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Outdoor Pollutants • Two main categories;
o Primary Pollutants
• Emitted directly into the air.
o Secondary Pollutants
• Primary pollutants that react with components of air to form new
harmful pollutants.
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Fig. 19-3, p. 442
Primary Pollutants
CO CO2 Secondary Pollutants
SO2 NO NO2
Most hydrocarbons SO3
Most suspended particles HNO3
H2O2 O3 PANs
Most NO3– and SO4
2– salts
Sources Natural Stationary
Mobile
H3SO4
Sources of Primary Pollutants
Pollutant Sources
Carbon Monoxide Incomplete burning of fossil fuels
Tobacco smoke
Hydrocarbons Incomplete burning of fossil fuels
Tobacco smoke
Chemicals
Particulates Burning fossil fuels
Farming operations
Construction operations
Industrial wastes
Building demolition
Sulfur Dioxide Burning fossil fuels
Smelting ore
Nitrogen Compounds Burning fossil fuels 9
Question • How does your daily lifestyle produce some of each
of the primary air pollutants shown in the previous
slide?
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News Good Bad
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• Over the past 30 years,
outdoor air quality in
most developed
countries has
improved.
• Passage of air pollution
laws.
• WHO estimates 1 out of
6 people on the earth
(1.1 billion) lives in
urban areas. o Poor air quality
• Most live in developing
countries.
• Major threat is from
indoor air pollution. o Heating and cooking
The Relationship • The problem of air pollution is directly related to the
size of the population living in an area and their
activities.
• If population is small and energy use is low, impact
is small. o Pollution is diluted and negative effect is slight.
• In urbanized, industrialized civilizations where use of
fossil fuels is high, we release large amounts of
pollution into the environment.
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Relationship • The released particles are mixed and diluted but
stay near the earth due to gravity. o We don’t get rid of it. We just dilute it and move it out of the immediate
area.
• In urbanized, industrialized areas, these particles do
not have time to dilute before reaching another
city. o This magnifies and adds to the problem.
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As an air mass moves across from west to east, each population adds to the total load in the atmosphere.
Health Risks • Pollution is not only ugly
to look at, it poses a
health risk. Especially
to: o Respiratory illness patients
o The elderly
o The very young
• Bronchial inflammation
• Allergic Reactions
• Irritations of mucous
membranes
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Donora • City in Pennsylvania
• October 1948
• Pollution from a zinc plant
and steel mills became
trapped in a valley
forming a dense smog.
• Within 5 days, o 17 people died
o 5,910 persons became ill
• Affected almost 50% of
the city’s 12,300
population.
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Megacities • What do Beijing, Seoul, Mexico City, and Cairo have
in common? o All are megacities in a developing world that have extremely poor air
quality.
• Each also exceed the W.H.O. guidelines for air
quality for at least two pollutants. o Air quality in Mexico City contributes to approximately 6,400 deaths each
year.
• Death rates increase and general health of
population is lowered.
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Major Air Pollutants • These include:
oCarbon Oxides
oNitrogen Oxides
o Sulfur Oxides
o Suspended Particulate Matter
oVolatile Organic Compounds
oOzone
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Carbon Oxides • The two main oxides of carbon that we will focus on
are:
o Carbon monoxide
o Carbon dioxide
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Carbon monoxide (CO) • Odorless, colorless, highly toxic gas.
• Forms from incomplete combustion of carbon-
containing materials. o 2C + O2 2CO
• Major sources o Motor Vehicle Exhaust
o Tobacco smoke
o Clearing and burning of forests/grasslands
o Open fire cooking and inefficient stoves
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Health Risks of CO • Reacts with hemoglobin in red blood cells.
o A protein in RBC that carries oxygen.
• Reduces ability of blood to transport oxygen.
• Chronic exposure can trigger o Heart attacks
o Aggravate lung diseases
• Asthma
• Bronchitis
• Emphysema
• High levels cause headaches, nausea, drowsiness, mental impairment, collapse, coma, and death.
• Several hours of exposure to 0.001% concentration can cause death.
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Whatchathinkboutit? • The two major sources are motor vehicle exhaust
and tobacco smoke.
• Knowing the health implications, put yourself on any
of the interstates around Atlanta, GA, on a warm
day, between the hours of 4:00 p.m. and 6:00 p.m..
• Discuss with your group any potential problems with
driver alertness. List your answers on paper and be
prepared to share with the class.
• 5 Minutes to discuss
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Effects of CO on Driver • The amount of CO produced in heavy traffic can
cause headaches, drowsiness, and blurred vision.
• A heavy smoker in traffic is doubly exposed and
may experience severely impaired reaction time
compared to nonsmoking drivers.
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Good News • CO is not a persistent pollutant.
• Natural processes convert CO to other non-harmful
compounds.
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Carbon dioxide (CO2) • A colorless, odorless gas.
• About 93% of CO2 in the troposphere is the result of
the natural carbon cycle.
• Remaining 7% results from human activities. o Burning fossil fuels
o Clearing forests/grasslands
• Not regulated by the U.S. Clean Air Act o Deep-pocket lobbyist.
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Nitrogen Oxides • Nitrogen Oxide (NO) is a colorless gas.
o Reaction of Nitrogen and Oxygen in high-temp combustion.
o N2 + O2 2NO
• Nitrogen dioxide (NO2) reacts with water in the
atmosphere to form: o Nitric acid (HNO3)
o Nitrate salts (NO3-)
• Plays a role in the formation of photochemical
smog.
• Nitrous oxide (N2O) is a greenhouse gas emitted
from fertilizers, animal wastes, and burning fossil fuels
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Sulfur Oxides • Sulfur dioxide (SO2) is a colorless gas with a bad
odor.
• 1/3 of the amount in troposphere comes from
natural sources. 2/3’s come from human sources. o Use of coal to produce electricity, oil refining, smelting
• Can react with water vapor to form sulfuric acid
(H2SO4) and sulfate salts (SO42-). These can lead to
acid deposition.
• Aggravate respiratory problems, corrode metals,
damage paint, paper, leather, and stone.
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SPM • Suspended Particulate Matter – solid particles and
liquid droplets small and light enough to stay suspended in the air for short to long periods of time.
• 62% comes from natural sources. o Dust, Wildfires, sea salt nuclei
• 38% from human sources o Plowing fields, road construction, unpaved roads, tobacco smoke, coal-
burning industrial plants, motor vehicles
• Fine SPM (PM-10) is ≤ 10 microns
• Ultrafine SPM (PM-2.5) is ≤ 2.5 microns
• Results in approximately 60,000 premature deaths per year in the U.S.
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Ozone • O3
• O2 + UV light + O O3
• Colorless and highly reactive gas
• Good in stratosphere but bad in troposphere
• Major component of photochemical smog.
• Can cause and aggravate respiratory problems.
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VOCs • Volatile Organic Compounds- organic compounds
that exist as gases in the air.
• Mostly hydrocarbons such as isoprene (C3H8) and
terpenes (C10H15) that are emitted by plant leaves,
and methane (CH4).
• 1/3 of methane emission are natural (plants,
wetlands, and termites)
• 2/3’s of methane is from human sources (rice
paddies, landfills, oil and gas wells, cow farts)
• Others include benzene, vinyl chloride, and
trichlorethylene.
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Radon (Rn) • #86 on Periodic Table; one of the Nobel Gases
• Radioactive gas found in some types of rock and
soils.
• Seeps into homes and buildings that are situated
above the source.
• Has been linked to lung cancer.
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Photochemical Smog • A chemical reaction that is activated by light.
• A mixture of primary and secondary pollutant in the
presence of UV radiation
• VOC’s + Nox + heat + UV photochemical smog o Mixture of Ozone, nitric acid, aldehydes, peroxyacl nitrates and other
secondary pollutants
• Hotter days lead to increased levels of ozone and
other components. As traffic increases, smog
increases.
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5 Factors Reducing Air Pollution
• Heavier particles settle out due to gravity.
• Precipitation helps to clean the air of pollutants
• Salty sea spray can wash out PM and soluble
pollutants
• Winds carry pollutants away and help dilute by
mixing actions
• Chemical reactions in the atmosphere
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6 Factors Increasing Air Pollution
• Buildings can reduce wind speed causing less
dilution
• Surrounding hills and mountains can reduce air flow
to valleys
• Higher temperatures promote chemical reactions
to form photochemical smog
• VOC emissions from certain trees and plants (some
oaks, sweet gums, poplars, and kudzu)
• Grasshopper effect- pollutants are transported from
tropics toward poles.
• Temperature inversions
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Acid Deposition • a.k.a. Acid Rain
• Industrial smokestacks can input SOx and NOx above the inversion
• Reduces local but increases regional pollution
• These pollutants may travel over 600 miles (1000 m) o Along the way, they form secondary pollutants from the chemical reactions
with the water vapor
• Descend in two forms o Wet deposition
• pH less than 5.6
• rain, snow, fog, cloud vapor
• 4 – 14 days
o Dry depostion
• acidic particles
• 2 -3 days
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Acid Deposition • Regional issue from coal-fired plants and areas with
many cars.
• Eastern U.S. precipitation is about pH 4.4 – 4.7 o 10x greater than normal rain which has a pH of 5.6
• Mountains in Eastern U.S. and those east of Los
Angeles have fog and dew with a pH of 2.3 o this is more acidic than lemon juice
o 1000 times greater than normal rain
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Acid Deposition • In soil, some compounds such as limestone (CaCO3)
can react with the acid to help neutralize it. o This is known as Buffering
• On mountains, there is a thin soil layer so the
buffering is minimal
• Some areas have received so much deposition that
the soil is unable to buffer the acids.
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Effects of Acid Deposition • Contributes to respiratory illnesses
• Leaching of toxic metals into water supplies o Biomagnification of Hg
• Building and Monument damage
• Car finishes
• Increase of acidity in aquatic ecosystems
• Farms and cropland
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