Transcript The Atmosphere and Air Quality Notes

The Atmosphere and Air
Quality Notes
The Earth’s Atmosphere
Troposphere
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75% of mass of atmosphere
0 to 11 miles in altitude
78% nitrogen, 21% oxygen
Location of Earth’s weather
Temperature decreases with altitude until
the next layer is reached, where there is a
sudden rise in temperature
Stratosphere
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11 miles to 30 miles in altitude
Calm
Temperature increases with altitude
Contains 1000x the ozone of the rest of the
atmosphere; ozone forms in an equilibrium
reaction when oxygen is converted to O3 by
lightning and/or sunlight
99% of ultraviolet radiation (especially
UV-B) is absorbed by the stratosphere
Mesosphere
30 to 50 miles in altitude
 The temperature decreases with
increasing altitude
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Thermosphere
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50 to 75 miles in altitude
Temperature increases with
increasing altitude
Very high temperatures
Air Issues
Pollution
AnthropogenicCaused by man’s activities
(transportation, power plants, industry)
Primary Pollutants
Released directly into the
atmosphere
Volatile Organic Compounds
(VOC’s)
 These may cause cancer. They
are released by burning
hydrocarbons (gasoline, etc.)
Nitrogen Oxides
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These may cause lung irritation,
bronchitis, and acid rain. They’re
released by burning fuels.
Sulfur Oxides
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These may cause emphysema,
bronchitis, and acid rain, and are
released by burning fuels and
industry.
Particulates
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These may irritate the respiratory
system and cause cancer, and are
released by combustion and
industry
Carbon Monoxide
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It may cause death and confusion.
It is released from the combustion
of fossil fuels.
Miscellaneous
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Arsenic (from smelters; deadly),
lead (from smelters; lowers IQ),
mercury (from smelters;
schizophrenia) radioactive
elements.
Secondary Pollutants
Form when primary
pollutants react
Smog
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Interaction between volatile organic
compounds and nitrogen oxides. It often
contains ozone, and may cause asthma
and emphysema.
Comes from car emissions reacting w/
sunlight.
Acid Rain
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Interaction between sulfur, nitrogen oxides,
& water converted into H2SO4 and HNO3.
It damages buildings, weakens plants,
causes plants & animals to absorb toxic
metals, & causes an overgrowth (too much
nitrogen) that depletes soil. It is primarily a
problem in the NE U.S. and Europe.
Comes from coal power plants, industrial
plants and transportation.
Air Quality is better in US; EPA
estimates since 1970
Particulate Matter (PM)- down 78%
 Carbon Dioxide (CO2)- down 23%
 Nitrogen Dioxide (Nox)- up 14%
 Lead (Pb)- down 98%
 Sulfur Dioxide (SO2)- down 32%
Air quality is worse in developing countries:
Mexico City & Beijing: air exceeds WHO
standards 350 days/year
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Natural Pollutants
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We have very little control over
these
Includes dust, pollen,
microorganisms, smoke, and
volcanic gases
Indoor Pollutants
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These may cause dizziness, headache,
and respiratory symptoms (asthma,
pneumonia, bronchitis and emphysema)
Include particulates, formaldehyde, and
asbestos
Radon- average level indoor 1.3 pCi/L
(picocuries per liter) and “action level” is
4.0 pCi/L. Hotspots- PA, NJ,NY and NC
mts0 causes lung cancer
Effects of Pollution
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Health of humans, livestock, wildlife,
plants, corrosion of metals, erosion
and discoloration of stone, and
disruption of soil nutrient cycles.
Amphibians and lichens are
especially sensitive (indicator
species)
Ozone Depletion
Ozone is Being Broken Down
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The ozone layer is being broken down
by chemical reactions with halides
(chlorine, fluorine, etc.) that are found
in refrigerants, aerosols, etc.
(Chlorofluorocarbons = CFC’s).
Holes in the Ozone Layer
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Holes and thin areas in the ozone
layer allow too much ultraviolet
radiation to hit Earth.
Effects of UV Radiation
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UV radiation damages the DNA in
cells, causing skin cancer,
cataracts, and plants tissue
damage.
Global Warming/
Greenhouse Effect
Cause of Global Warming
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Increased levels of carbon dioxide and
methane build up an extra layer in the
atmosphere that traps the heat from the
sun.
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on this is very controversial.
Benefits
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Possible Benefits could be an
increased productivity due to
higher temperatures and
availability of carbon dioxide.
Problems
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Possible problems could be an
overall climate change and
melting of the ice caps.
Relationships
Climate and Pollution
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Windy areas have less air pollution than
less windy areas
Cool, moist areas tend to develop into
“gray air” cities due to build-up of smog
Warm, dry areas tend to develop into
“brown air” cities due to the build-up of
photochemical smog (high levels of ozone)
CHEMICAL PROCESS OF PHOTOCHEMICAL SMOG:
Heat from vehicles, etc. produce nitric oxide which reacts with
oxygen to form nitrogen dioxide, a gas with a choking odor.
The nitrogen dioxide produces the brownish haze that hangs
over many cities.
CHEMICAL PROCESS OF INDUSTRIAL SMOG:
When burned, the carbon in coal and oil is converted to
Carbon Dioxide and carbon monoxide. The sulfur in the
coal and oil react with oxygen to produce sulfur dioxide, a
colorless, suffocating gas. This sulfur dioxide reacts with
oxygen to form sulfur trioxide, which then reacts with water
vapor in the air to produce sulfuric acid. This produces
industrial smog.
Topography and Pollution
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Mountainous areas tend to trap
pollution
Flat areas tend to allow pollution
to disperse
Temperature Inversions
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A layer of warm air traps a layer of cold air
underneath it; pollution is stuck in the
cooler air
Often a problem in mountainous areas
Subsidence inversions are large and longlasting
Radiation inversions are smaller and shortlived (caused by ground cooling faster than
the upper air)
Human Impact (Positive)
Pollution Control Devices
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Emission Control Devices – filter particles
Scrubbers – use water to filter particles
and gases
Catalytic Converters – on cars; finish
burning wastes to decrease carbon
monoxide levels
1-800-453-SMOG
Law – Clean Air Act
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1963 - first passage
1970, 1977 and 1990 - amended
Involves EPA
Sets standards for acceptable levels of sulfur
oxides, nitrogen oxides, ozone, carbon
monoxide, hydrocarbons, lead, & more
Provides pollution credits for industries that
utilize pollution-control devices+
Bush administration has relaxed rules
It established NAAQS and AQI
National Ambient Air Quality
Standards (NAAQS)
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Sets acceptable concentrations for 6 “criteria”
pollutants that:
 Threaten public health/the environment
over broad areas (non-point)
 Are emitted in large quantities
 CO, Pb, Nitrogen Oxides, Ozone,
Particulate Matter and Sulfur Dioxides
Air Quality Index (AQI)
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Measures levels of 5 criteria pollutants
Forecast of daily air pollution levels
Purpose to educate and protect publicfocuses on health effects
Categories: green= good, yellow=
moderate, orange= unhealthy for sensitive
groups, red= unhealthy, purple= very
unhealthy
National Emissions Standards for
Hazardous Air Pollutants
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Regulates emissions (from point sources)
For specific substances (air toxics w/
known or suspected serious health
effects (mutagens, carcinogens,
neurotoxins)
Tend to be localized, from point sources
Examples: Ammonia, chlorine, asbestos,
arsenic, mercury, benzene