Air & Air Pollution
See what you know
• What is in the air?
• What is the difference between Global
Warming and Climate Change?
• What causes Climate Change?
• What are the effects of Climate Change?
• What caused the hole in the ozone layer?
Choosing sides
• Whether climate change
is occurring or not, isn’t it
better to be on the side
that believes it is
happening? How can
changing our ways be a
bad thing? Isn’t it better to
error on the true side?
• Human-caused climate
change is happening, ..It
is happening faster than
anyone predicted even a
few years ago, and
therefore we need to
remind ourselves and
negotiators need to
remind themselves that
the longer we delay, the
more we will pay, both in
terms of lives and in
terms of money.
• - Robert Orr, a top UN
official
The
Atmosphere
Greenhouse gasses
Atmospheric Gases
Atmospheric pressure (millibars)
Temperature
Pressure
Thermosphere
Mesosphere
Heating via ozone
Stratopause
Stratosphere
Altitude (miles)
Altitude (kilometers)
Mesopause
Tropopause
Ozone “layer”
Heating from the earth
Troposphere
(Sea level)
Temperature (˚C)
Pressure = 1,000
millibars at ground
level
• Inches of Hg
• 1 atm = 29.92 Inches
of Hg
1atm = 29.92 Inches of Hg
1 atm = 14.696 lb/in2
The Atmosphere in layers
Troposphere
–
–
–
–
Layer in which we live
Most weather occurs here
90% of the gasses are here
0-6 mile above N and S Pole
• Mount Everest is 5.3 miles tall
– 0-10 miles above equator
– is made up mostly of nitrogen
and oxygen,
with smaller amounts of water
vapor and CO2
• Stratosphere
– 6-10 mile thick
– Air traffic due to lack of
weather
– Ozone layer
• Thermosphere
– 50 miles to space
“Good” Ozone Layer
• Ozone (O3) is a gas that occurs both in the Earth's upper
atmosphere and at ground level. Ozone can be "good" or
"bad" for your health and the environment, depending on
its location in the atmosphere.
• How much of our atmosphere is ozone?
• Ozone that surrounds the earth 12-35 miles above the
earth is our first line of defense of the sun’s ultraviolet
radiation. UVA, UVB, UVC
– This radiation can cause sunburn, skin cancer, cataracts, …
• Ozone is constantly created and destroyed
Humans need a small amount of ultraviolet
radiation to maintain health. Ultraviolet
radiation activates vitamin D in the
human body, which assists the intestines
in absorbing minerals. Humans, as well
as other life forms, can tolerate radiation
through the UVA range, but radiation with
shorter wavelengths, such as UVB and
UVC is harmful. Oxygen molecules
absorb the shortest and most harmful
UVC radiation and ozone absorbs
most of the remainder before it
reaches the earth’s surface. Ozone, a
molecule containing three oxygen atoms,
is made when the shortest wavelengths of
UVC are absorbed by oxygen and break
apart into two oxygen atoms.
What Happens to Solar Energy
Reaching the Earth?
• Solar energy
flowing through
the biosphere
warms the
atmosphere,
evaporates and
recycles water,
generates winds
and supports
plant growth.
Figure 3-8
Why is a sunset red?
Refraction – of light as it
passes through atmosphere
and collides with atmospheric
gasses. Colors are filtered
out and scattered.
The Natural Greenhouse Effect
• Three major factors shape the earth’s
climate:
– The sun.
– Greenhouse effect that warms the earth’s lower
troposphere and surface because of the
presence of greenhouse gases.
– Oceans store CO2 and heat, evaporate and
receive water, move stored heat to other parts of
the world.
– Natural cooling process through water vapor in
the troposphere (heat rises).
Major Greenhouse Gases
• The major greenhouse gases in the lower
atmosphere are water vapor(.04%), carbon
dioxide (.0369%), methane(.00018%), and
nitrous oxide(.0000315%), ozone (.000005%)
– These gases have always been present in the
earth’s troposphere in varying concentrations.
– Fluctuations in these gases, plus changes in solar
output are the major factors causing the changes in
tropospheric temperature over the past 400,000
years.
Greenhouse Effect
• This “greenhouse
effect” is vital for our
survival. Without heat
trapping gasses our
planet would be cold
and lifeless.
• The gasses act like a
car that gets hot
inside.
Albedo - %age of
incoming sunlight
reflected from a surface
Air Pollution – The Big 5
• Air Pollutant is defined as
any substance in the air
that is concentrated
enough to harm living
things or to cause
damage to man-made
objects.
• Primary pollutants –
released directly into air.
• Secondary pollutants –
primary pollutants react
with other components.
Primary Pollutants
CO CO2
SO2 NO NO2
Most hydrocarbons - VOCs
Most suspended particles
Sources
Natural
Secondary Pollutants
SO3
HNO3 H3SO4
H2O2 O3 PANs
Most NO3– and SO42– salts
Stationary
Mobile
Fig. 19-3, p. 442
Point Source / Nonpoint Source
Human Actions and Our
Environment
• When the human population was low,
there was very little impact to the
environment.
– Wind, rain, and time were the natural air
cleaners.
• As the human population increased, time
could not clean the air fast enough.
• Deforestation removes CO2 cleaners.
Human Actions and Our
Environment
•
The burning of fossil fuels -- notably coal, oil and gas -has accounted for about 80 percent of the rise of
atmospheric carbon dioxide since the pre-industrial
era. Humans have been burning fossil fuel for 400
years adding an enormous unnatural amount of carbon
dioxide and other gases in the air.
The human impact has changed three major
ecosystem cycles.
•
1.
–
–
–
The chemical cycles
Carbon Cycle
Nitrogen Cycle
Sulfur Cycle
–
By adding more chemicals we change the cycle
Air Pollution – The Big 5
1.
Carbon oxides
•
•
2.
High levels can suffocate you blood
Put out by automobiles and fires
Unburned Hydrocarbons - VOCs
•
•
•
3.
Combustion of gas
Oil based paint, dry cleaning fluids, petroleum fuels
Methane stores 25 x more energy than CO2.
Nitrogen Oxides
•
•
•
•
Nitrogen alone is Ok, but at high temps. It reacts with oxygen to
form NOx
Makes the sky Brown in smog
Photchemical smog – nitrogen and light form “bad “ozone”
PANs – Peroxyacyl nitrates
Air Pollution – The Big 5
• 4. Sulfur Oxides
– Naturally occurring
• Volcanoes
– Burning of coal, oil, gas (cars)
– Cause Lung damage, asthma, and bronchitis
– Combines with hydrogen to make Sulphuric Acid (ACID RAIN)
• 5. Particulates
• - PM10 – smaller than 10 um – human hair is about 50-100 um
– Small solid particles or liquid droplets in the air
• Light enough to float in air
• Dust, lead, mercury, radon, ash from fires, road dust, exhaust, wind
erosion,
• Lung irritant, stain buildings, reduce visibility
Major Air Pollutants
• Carbon oxides – CO , CO2:
– CO2 (10,000 ppm) will make some people feel
drowsy. Exhaling into a bag is about 37,000 ppm.
– Carbon oxides are highly toxic gasses that form
during the incomplete combustion of carboncontaining materials.
– 93% of carbon dioxide (CO2) in the troposphere
occurs as a result of the carbon cycle.
– 7% of CO2 in the troposphere occurs as a result of
human activities (mostly burning fossil fuels).
– CO2 is a greenhouse gas
Major Air Pollutants
• Nitrogen oxides and nitric acid:
– Nitrogen oxide (NOx) forms when nitrogen
and oxygen gas in air react at the highcombustion temperatures in automobile
engines and coal-burning plants. NO can also
form from lightening and certain soil bacteria.
– Photochemical Smog
• NO reacts with air to form NO2.
• NO2 reacts with water vapor in the air to form nitric
acid (HNO3) and nitrate salts (NO3-) which are
components of acid deposition.
The
Nitrogen
Cycle:
The first thing that starts the chain of events is that people start driving in the
morning. As gasoline is burned, nitrogen (N2) in the atmosphere is also burned, or
oxidized, forming nitric oxide (NO)
N2 + O2=2NO
Hydrocarbons and carbon monoxide (CO) will also be emitted by cars. Hydrocarbons
are volatile organic compounds that may include acetaldehyde, formaldehyde,
ethylene, and many other compounds.
In the air, nitric oxide combines with molecular oxygen to form nitrogen dioxide within a
few hours.
2NO + O2--------->2NO2
Nitrogen dioxide absorbs light energy and splits to form nitric oxide and atomic oxygen:
NO2-->NO + O
Then, in sunlight, the atomic oxygen combines with oxygen gas to form ozone (O3):
O+ O2--->O3
If no other factors are involved, ozone and nitric oxide then react to form nitrogen
dioxide and oxygen gas.
O3 + NO<------>NO2 + O2
This last reaction can go in either direction, depending on temperature and the amount
of sunlight. If there is a lot of sunlight, the equation moves to the left, and more
ozone is produced. If nothing else gets in the way, an equilibrium is reached, and
the ozone level stabilizes.
However, there is something else involved. Remember that the cars are also emitting
hydrocarbons as well as oxides of nitrogen. Hydrocarbons are the other main
ingredient in photochemical smog. When hydrocarbons are present, nitric oxide
reacts with them instead of the ozone. This reaction produces a variety of toxic
products, such as a volatile compound known as PAN (peroxyacetyl nitrate).
NO + hydrocarbons----------------->PAN and various other compounds. Also,
NO2 +hydrocarbons------------------>PAN and various other compounds
Major Air Pollutants
• Volatile organic compounds
(VOCs):
– Most are hydorcarbons emitted by the leaves
of many plants.
– About two thirds of global methane CH4
emissions comes from human sources.
– Other VOCs include industrial solvents such
as trichlorethylene (TCE), benzene, and vinyl
chloride, hundreds more.
• Long-term exposure to benzene can cause cancer,
blood disorders, and immune system damage.
Methane CH4
• About 25x stronger GHG
than CO2.
• 1/3rd of methane
emissions come from
natural sources, mostly
plants, wetlands,
termites, anaerobic
decomposition.
• The rest comes from
human sources such as
rice paddies, landfills, oil
and natural gas wells,
and cows (from belching
or flatulence).
Major Air Pollutants
• Ozone (O3):
– “bad” ozone - found in
troposphere
– Is a highly reactive gas
that is a major
component of
photochemical smog.
– It can
• Cause and aggravate
respiratory illness such
as asthma
• Can aggravate heart
disease.
• Damage plants
What Causes "Bad" Ozone?
Ground-level or "bad" ozone is
not emitted directly into the air,
but is created by chemical
reactions
VOC + NOx + Sunlight = Ozone (O3)
Emissions from industrial
facilities and electric utilities,
motor vehicle exhaust, gasoline
vapors, and chemical solvents
are some of the major sources
of NOx and VOC.
Ozone Action Days
• Usually occur days
that are:
–
–
–
–
Relatively Hot
Dry
Clear
Little to no wind
• Ozone action days
can be predicted
Major Air Pollutants
• Sulfur dioxide (SO2) and sulfuric acid:
– About one-third of SO2 in the troposphere
occurs naturally through the sulfur cycle.
– Two-thirds come from human sources, mostly
combustion (S+ O2  SO2) of sulfurcontaining coal and from oil refining and
smelting of sulfide ores.
– SO2 in the atmosphere can be converted to
sulfuric acid (H2SO4) and sulfate salts (SO42-)
that return to earth as a component of acid
deposition.
Sulfur in from burning of fuels.
• Combustion of gas in
automobiles releases
sulfur.
• Burning of coal
releases sulfur. The
United States creates
a great majority of its
electricity by burning
coal.
The Sulfur Cycle
Figure 3-32
ACID DEPOSITION
• Sulfur dioxides, nitrogen oxides, and
particulates can react in the atmosphere to
produce acidic chemicals that can travel
long distances before returning to the
earth’s surface.
– Tall smokestacks reduce local air pollution but
can increase regional air pollution.
Acid Deposition
• AKA Acid Rain
• Rain cleans the air, but pollutes the water.
• Normal rainwater has a pH of 5.6 (slightly
acidic). This is because it is exposed to the
carbon dioxide in the atmosphere. The
carbon dioxide gets dissolved in the
rainwater and forms carbonic acid (H{-2}CO{-3}).
Acid Rain is anything below 5.6.
• Plants like to grown in soil with a pH of 6-7
• What happens to the plants?
ACID RAIN
Wind
Transformation to
sulfuric acid
(H2SO4) and nitric
acid (HNO3)
Nitric oxide (NO)
Windborne ammonia gas and
particles of cultivated soil
partially neutralize acids and
form dry sulfate and nitrate
salts
Sulfur dioxide
(SO2) and NO
Acid fog
Dry acid deposition
(sulfur dioxide gas and
particles of sulfate and
nitrate salts)
Farm
Ocean
Lakes in deep
soil high in
limestone are
buffered
Wet acid depostion
(droplets of H2SO4
and HNO3 dissolved
in rain and snow)
Lakes in shallow soil
low in limestone
become acidic
Fig. 19-6, p. 448
ACID DEPOSITION
• pH measurements in relation to major
coal-burning and industrial plants.
ACID DEPOSITION
• Air pollution is
one of several
interacting
stresses that
can damage,
weaken, or kill
trees and
pollute surface
and
groundwater.
ACID DEPOSITION
• Acid deposition contributes to chronic
respiratory disease and can leach toxic
metals (such as lead and mercury) from
soils and rocks into acidic lakes used as
sources for drinking water.
Solutions
Acid Deposition
Prevention
Reduce air pollution
by improving
energy efficiency
Cleanup
Add lime to
neutralize
acidified lakes
Reduce coal use
Increase natural
gas use
Increase use of
renewable energy
resources
Add phosphate
fertilizer to
neutralize
acidified lakes
Burn low-sulfur coal
Remove SO2
particulates & NOx
from smokestack
gases
Remove NOx from
motor vehicular
exhaust
Tax emissions of SO2
Fig. 19-10, p. 452
Major Air Pollutants
• Suspended particulate matter (SPM):
– Consists of a variety of solid particles and
liquid droplets small and light enough to
remain suspended in the air.
– The most harmful forms of SPM are fine
particles (PM-10, with an average diameter <
10 micrometers) and ultrafine particles (PM2.5).
– According to the EPA, SPM is responsible for
about 60,000 premature deaths a year in the
U.S.
SPMs
•
•
•
•
•
Lead
Mercury
Pollen
Soil
Liquids
What is Happening to the "Good"
Ozone Layer?
Ozone is produced naturally in the stratosphere. But this "good"
ozone is gradually being destroyed by man-made chemicals referred
to as ozone-depleting substances (ODS), including
chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs),
halons, methyl bromide, carbon tetrachloride, and methyl chloroform.
These substances were formerly used and sometimes still are used in
coolants, foaming agents, fire extinguishers, solvents, pesticides, and
aerosol propellants (propane).
Atmospheric pressure (millibars)
Temperature
Pressure
Thermosphere
Heating via ozone
Mesosphere
Stratopause
Stratosphere
Altitude (miles)
Altitude (kilometers)
Mesopause
Tropopause
Ozone “layer”
Heating from the earth
Troposphere
(Sea
level)
Temperature (˚C)
Pressure = 1,000
millibars at ground
level
Fig. 19-2, p. 440
Ozone
• CFC – Chlorofluorocarbons react with an
oxygen atom to break down O3 to O2.
• 1 chlorine can destroy 100,000 ozone molecules
• As ozone is broken down, the ozone layer gets
thinner.
– This radiation that gets through can cause sunburn,
skin cancer, cataracts, …
Ultraviolet light hits a chlorofluorocarbon
(CFC) molecule, such as CFCl3, breaking
off a chlorine atom and
leaving CFCl2.
Sun
Cl
UV radiation
The chlorine atom attacks
an ozone (O3) molecule,
pulling an oxygen atom off
it and leaving an oxygen
molecule (O2).
Summary of Reactions
CCl3F + UV Cl + CCl2F
Cl + O3 ClO + O2
Repeated
Cl + O Cl + O2
many times
Once free, the chlorine atom is off
to attack another ozone molecule
and begin the cycle again.
A free oxygen atom pulls
the oxygen atom off
the chlorine monoxide
molecule to form O2.
The chlorine atom
and the oxygen atom
join to form a chlorine
monoxide molecule
(ClO).
Fig. 20-18, p. 486
OZONE DEPLETION IN THE
STRATOSPHERE
• Since 1976, in Antarctica, ozone levels have markedly
decreased during October and November.
Figure 20-20
Natural Capital Degradation
Effects of Ozone Depletion
Human Health
• Worse sunburn
• More eye cataracts
• More skin cancers
• Immune system suppression
Food and Forests
• Reduced yields for some crops
• Reduced seafood supplies from reduced phytoplankton
• Decreased forest productivity for UV-sensitive tree species
Wildlife
• Increased eye cataracts in some species
• Decreased population of aquatic species sensitive to UV radiation
• Reduced population of surface phytoplankton
• Disrupted aquatic food webs from reduced phytoplankton
Air Pollution and Materials
• Increased acid deposition
• Increased photochemical smog
• Degradation of outdoor paints and plastics
Fig. 20-21, p. 488
Global Warming
• Accelerated warming because of decreased ocean uptake of CO2 from
atmosphere by phytoplankton and CFCs acting as greenhouse gases
Montréal Protocol
• The Montreal Protocol, adopted in 1987, required
nations to freeze production levels of CFCs. Additional
agreements enacted since 1987 accelerated the CFC
phase out timetable to December 31, 1995.
• Atmospheric concentrations of chlorofluorocarbons
peaked in 1994 and began to decrease in 1995, marking
the first time that a atmospheric concentrations of
chlorine began to decrease. Chlorine concentrations in
July 2002, were about 5% less than the 1994 peak.
However, the amount of atmospheric bromine continues
to increase, albeit at a slower rate.
What Can You Do?
Reducing Exposure to UV Radiation
• Stay out of the sun, especially between 10 A.M. and 3 P.M.
• Do not use tanning parlors or sunlamps.
• When in the sun, wear protective clothing and sun–
glasses that protect against UV-A and UV-B radiation.
• Be aware that overcast skies do not protect you.
• Do not expose yourself to the sun if you are taking
antibiotics or birth control pills.
• Use a sunscreen with a protection factor of 15 or 30
anytime you are in the sun if you have light skin.
• Examine your skin and scalp at least once a month for
moles or warts that change in size, shape, or color or
sores that keep oozing, bleeding, and crusting over. If
you observe any of these signs, consult a doctor
immediately.
Fig. 20-23, p. 490
Topography and Pollution
• Geography can effect
pollution
concentrations.
• Mountainous areas
tend to trap pollution
• Flat areas tend to
allow pollution to
disperse
• Forest Fires in the
Los Angeles area.
• Winds carry the
smoke across the
ocean.
• Wind can clean the
air, but it can also
spread it somewhere
else.
China Air Pollution
• A regions air pollution
can become a global
problem.
Temperature Inversion
• Cold air is more
dense. Sometimes
when it sinks below
the warm air, it
brings the pollution
with it.
Temperature Inversions
• Cold, cloudy weather in a valley
surrounded by mountains can trap air
pollutants (left).
• Areas with sunny climate, light winds,
mountains on three sides and an ocean on
the other (right) are susceptible to
Figure 19-5
How does air quality effect me?
•
•
•
•
•
•
•
Asthma
Emphysema
Allergies
Heart disease
Drink polluted water
Colds
Pneumonia
National Ambient Air Quality
Standards (NAAQS)
• 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
HEALTH EFFECTS OF AIR
POLLUTION
• Your respiratory system can help protect you
from air pollution, but some air pollutants can
overcome these defenses.
Figure 19-14
Air Pollution is a Big Killer
• Each year, air pollution
prematurely kills about 3
million people, mostly from
indoor air pollution in
developing countries.
– In the U.S., the EPA
estimates that annual deaths
related to indoor and outdoor
air pollution range from
150,000 to 350,000.
HEALTH EFFECTS OF AIR
POLLUTION
Normal human lungs (left) and the lungs of a
person who died of emphysema (right).
Figure 19-15
Air Pollution is a Big Killer
• Spatial distribution of premature deaths
from air pollution in the United States.
Figure 19-16
Clean Air Act
•
•
•
•
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, PANs,
particulate matter & more. Does not regulate
CO2.
• Provides pollution credits (subsidies) for
industries that utilize pollution-control devices+
• Bush administration has relaxed rules
• Does not regulate 2&4 cycle small engines
PREVENTING AND REDUCING
AIR POLLUTION
• Environmental scientists point out several
deficiencies in the Clean Air Act:
– The U.S. continues to rely on cleanup rather than
prevention.
– The U.S. Congress has failed to dramatically
increase fuel-efficiency standards for automobiles.
– Regulation of emissions from motorcycles and twocycle engines remains inadequate.
– There is little or no regulation of air pollution from
oceangoing ships in American ports.
PREVENTING AND REDUCING
AIR POLLUTION
• Executives of companies claim that
correcting these deficiencies would cost
too much, harm economic growth, and
cost jobs.
What Is Being Done About "Bad"
Ozone?
Under the Clean Air Act, EPA has set protective
health-based standards for ozone in the air we
breathe. EPA, state, and cities have instituted a
variety of multi-faceted programs to meet these
healthbased standards. Throughout the country,
additional programs are being put into place to cut
NOx and VOC emissions from vehicles, industrial
facilities, and electric utilities. Programs are also
aimed at reducing pollution by reformulating fuels
and consumer/commercial products, such as
paints and chemical solvents, that contain VOC.
PCBs
• Polychlorinated biphenyls (PCBs) were widely used
as dielectric and coolant fluids. Due to PCBs' environmental toxicity and
classification as a persistent organic pollutant, PCB production was banned
by the United States Congress in 1979 and by the Stockholm Convention on
Persistent Organic Pollutants in 2001.
• A number of peer-reviewed health studies have shown an association
between exposure to PCBs and non-Hodgkin Lymphoma, a frequently fatal
form of cancer
• Concerns about the toxicity of PCBs are largely based on compounds within
this group that share a structural similarity and toxic mode of
action with dioxin. Toxic effects such as endocrine
disruption and neurotoxicity are also associated with other compounds
within the group.
Solutions:
Reducing Outdoor Air Pollution
• There are a of ways to prevent and control
air pollution from motor vehicles.
– Because of the Clean Air Act, a new car today
in the U.S. emits 75% less pollution than it did
pre-1970 cars.
– There is an increase in motor vehicle use in
developing countries and many have no
pollution control devices and burn leaded
gasoline.
Solutions
Motor Vehicle Air Pollution
Prevention
Mass transit
Cleanup
Emission
control devices
Bicycles and
walking
Less polluting
engines
Less polluting fuels
Improve fuel efficiency
Car exhaust
inspections
twice a year
Get older, polluting
cars off the road
Give buyers large tax
write-offs or rebates for
buying low-polluting,
energy efficient
vehicles
Stricter
emission
standards
Fig. 19-19, p. 460
Solutions:
Reducing Outdoor Air Pollution
• There are a of ways to prevent and control
air pollution from coal-burning facilities.
– Electrostatic precipitator: are used to attract
negatively charged particles in a smokestack
into a collector.
– Wet scrubber: fine mists of water vapor trap
particulates and convert them to a sludge that
is collected and disposed of usually in a
landfill.
Electrostatic Precipitator
• Can remove 99% of
particulate matter
• Does not remove
hazardous ultrafine
particles.
• Produces toxic dust
that must be safely
disposed of.
• Uses large amounts
of electricity
Figure 19-18
Wet Scrubber
• Can remove 98%
of SO2 and
particulate matter.
• Not very effective
in removing
hazardous fine and
ultrafine particles.
Figure 19-18