Transcript Document 7170088

AIR POLLUTION
Dr. Wesam Al
Madhoun
What is air pollution?
• The presence of any substances in the
atmosphere in quantities which are or may
be harmful or injurious to human health,
welfare, animal or plant life, or property or
unreasonably interfere with the enjoyment
of life or property.
2
Outdoor Air Pollution
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
Primary vs. Secondary Pollutants
• Primary- put directly into
air from polluting source.
• Secondary- when primary
combines with other
substances in air and
creates something more
hazardous (acid rain,
smog)
• Sun often provides
energy.
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, farm equipment, and
construction machinery.
Natural Sources
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Forest fires- ash, particulates, carbon dioxide
Volcanoes- ash, acid mist, hydrogen sulfide
Decaying vegetation- sulfur cmpds
Trees & bushes- Volatile Organic Cmpds (VOC’s)
Pollen
Viruses
Bacteria
Dust- from storms in arid regions
Gut bacteria- methane gas
Anthropogenic Sources
of Air Pollution
Criteria Air Pollutants
EPA uses seven "criteria pollutants" as indicators
of air quality
1.
2.
3.
4.
5.
6.
7.
Sulfur Dioxide: SO2
Nitrogen Dioxide: NO2
Carbon monoxide: CO
Lead: Pb
Particulate Matter: PM10 (PM 2.5)
Volatile Organic Compounds: (VOCs)
Ozone: ground level O3
Sulfur Dioxide (SO2)
• Properties: colorless gas with irritating odor
• Effects: produces acid rain (H2SO4), breathing
difficulties, eutrophication due to sulfate formation.
• Sources: burning high sulfur coal or oil in power
plants, smelting or metals, paper manufacture
• Class: sulfur oxides
• EPA Standard: 0.3 ppm (annual mean)
• 2nd largest cause of air pollution-related health
damage. (1st is smoking)
• Sulfate particles reduce visibility in the U.S. as much
as 80%
• Reflects sunlight so may have cooling effect
Sulfur Dioxide
Emissions
Nitrogen Dioxide (NO2)
• Properties: reddish brown gas, formed as fuel
burned in car, strong oxidizing agent, forms
Nitric acid (HNO3) 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,
fertilizers
• Class: Nitrogen oxides (NOx)
• EPA Standard: 0.053 ppm
• Excess nitrogen is causing fertilization &
eutrophication of inland waters & seas
Mobile Source Emissions:
Nitrogen Oxides
Carbon Monoxide (CO)
• Properties: colorless, odorless, heavier than air,
0.0036% of atmosphere
• Effects: binds tighter to Hemoglobin (Hb) than O2,
so organs do not get O2 needed, makes you
sleepy, impairs 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
• 1 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 levels
• Sources: particulates from fuel combustion, smelters,
batteries
• Class: toxic or heavy metals
• EPA Standard: 1.5 ug/m3
• 2 million tons enter atmosphere/year
• Mercury- neurotoxin from coal power plants
• Both mercury & lead travel on air currents and fall into
aquatic ecosystems causing bioaccumulation &
biomagnification in food webs.
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
(polychlorinated biphenyls), dioxins, pesticides
•EPA Standard: 50 ug/m3 (annual mean)
• PM2.5 is worse because small enough to be inhaled more deeply
• Asbestos fibers & cigarette smoke are most dangerous
respirable particles because they are carcinogenic
Mobile Source Emissions: Fine
Particulate Matter (PM2.5)
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, wetlands, rice
paddies, bacteria, plants.
• Class: HAPs (Hazardous Air Pollutants- cause cancer, birth
defects, mutation, neutroxins)
– Methane
– Benzene
– Chlorofluorocarbons (CFCs), etc.
• Concentrations indoors up to 1000x outdoors
• 600 million tons of CFCs
Ozone (O3)
• Properties: colorless, unpleasant odor, major part
of photochemical smog
• Effects: lung irritant, damages plants, rubber,
fabric, eyes
• Sources: Created by sunlight acting on NOx and
VOC , photocopiers, cars, industry, gas vapors,
chemical solvents, incomplete fuel combustion
products
• Class: photochemical oxidants
• Good ozone vs. bad ozone- good is in stratosphere
and bad is at ground level (from cars)
• Figure 18.10 shows secondary production of urban
smog by photochemical rxns in atmosphere
Other Air Pollutants
• Carbon dioxide- natural source from
photosynthesis & respiration; human caused
from fossil fuels & deforestation
• ChloroFluoroCarbons (CFC’s)- from
refrigerants, aerosols, Styrofoam
• Formaldehyde- building materials &
household products
• Benzene- paint
• Asbestos- car brakes, building materials
• Dioxins- pesticides
• Cadmium- batteries, plastics industry
Formation & Intensity of Pollutant is
influenced by…
• Local climate (inversions, air pressure, temperature, humidity)
• Topography (hills and mountains)
• Population density
• Amount of industry
• Fuels used by population and industry for heating,
manufacturing, transportation, power
• Weather: rain, snow, wind
• Buildings (slow wind speed)
• Mass transit used
Thermal Inversion
- occur in valleys
-pollutant effects are intensified when air cannot move
upward due to cold upper air layer
cool air
Pollutants
cool air
warm air (inversion layer)
warm
air
• surface heated by sun
• warm air rises (incl. pollutants)
• cools off, mixes with air of equal
density & disperses
• surface cools rapidly (night)
• a layer of warm air overlays surface
• polluted surface air rises but cannot
disperse  remains trapped
Smog Forms
...when polluted air is stagnant
(weather conditions, geographic location)
Los Angeles, CA
Solar
radiation
Photochemical Smog
Ultraviolet radiation
NO
Nitric oxide
NO2
Nitrogen
dioxide
H2O
Water
O
Atomic
oxygen
O2
Molecular
oxygen
Hydrocarbons
PANs
Peroxyacyl
nitrates
HNO3
Nitric acid
Aldehydes
(e.g., formaldehyde)
O3
Ozone
Photochemical Smog
Urban Heat Islands
• Cities are generally 3-5ºC warmer than
rural areas
• Caused by:
– Lack of vegetation to absorb heat
– Dark buildings & roads trap heat
– Buildings create windbreaks
• Dust Dome- trapping of dirt & particulates
over city
INDOOR AIR POLLUTION
What are some sources of
indoor air pollution?
1. Cigarette smoke
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–
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Deadliest indoor air
pollutant
Contain formaldehyde,
carbon monoxide
Causes lung cancer,
emphysema
Second hand smoke may
be worse due to
particulates that come
from tip.
What are some sources of
indoor air pollution?
2. Mold
– Moisture in carpets
– Allergy symptoms,
breathing problems,
headache, fatigue
What are some sources of
indoor air pollution?
3. Carbon monoxide
– Malfunctioning
furnace, gas
appliances, cars
– Blood cannot carry
oxygen
– Feel sleepy,
nausea, dizzy,
cause death.
What are some sources of
indoor air pollution?
4. Radon
–
–
–
–
–
Colorless, odorless,
radioactive gas
Comes from soil under
basements
Long term exposure can
cause lung cancer
Fix cracks in floor or walls
to prevent influx of radon
Install ventilation fan in
basement to blow radon
out.
Zone 1 (purple) high levels of radon
Zone 3 (yellow) low levels of radon
What are some sources of
indoor air pollution?
5. Asbestos
– Roofing, flooring,
insulation, brakes
– OK… unless
disturbed or
deteriorates
– Can cause
asbestosis (scarring
of lungs) and
mesothelioma (type
of lung cancer)
Plaque build up (scarring)
in lung w/asbestosis
What are some sources of
indoor air pollution?
6. Lead
– Old homes, toys,
lead crystal dishes
– Causes behavior &
learning problems,
slow growth, hearing
problems, headaches
What are some sources of
indoor air pollution?
7. Formaldehyde
– Pressed wood,
paneling, particle
board, glue.
– Respiratory irritation,
fatigue, skin rash,
known to cause
cancer
What are some sources of
indoor air pollution?
8. VOC’s
– Paradichlorobenzenemothballs, insecticides
– (perchloroethylene))- dry
cleaned clothes
– Benzene- paints,
cigarettes
– Causes respiratory
problems, headaches,
loss of coordination,
nausea, organ damage,
cancer
Effects of Air Pollution on…
1. Human Health
2. Plant Health
3. Acid Deposition
1. Human Health
• Depends on intensity & duration of
exposure, age & prior health status
• At-risk groups: young, old, or already
suffering from respiratory/cardiovascular
disease. Also, more active & outside vs.
sedentary inside lifestyle
• Most susceptible- less-developed
countries use smoky fires for cooking &
heating
Exposure
• Time spent in various environments in US and
less-developed countries
How is it introduced to body?
• Inhalation
• Absorption thru skin
• Contamination of food & water
How does air pollution affect
people?
• Chronic bronchitiscoughing, trouble
breathing
• Asthma- not caused by
air pollution, but
aggravated by it.
• Emphysema- lungs lose
elasticity, hard to breathe
• Lung Cancer- caused by
cigarettes, car exhaust,
particulates, asbestos,
arsenic, radon

How does air pollution
Sick building syndrome- affect people?
– Buildings closed up to
save energy- no
circulation
– Effects of fumes
intensified
– Symptoms: headache,
eye or throat irritation,
cough, itchy skin,
dizziness, nausea, fatigue
– Feel better when you get
fresh air outside.
– ≥20% of workers must be
afflicted to be classified as
SBS
2. Plant Health
•
Two Methods of Damage
– Directly toxic
• Irritate cell membranes
• First few days- discoloration due to
chlorosis (bleaching) of leaf
• Later- necrotic (dead) lesions develop
leading to death
– Disruption of plant hormones
• Ethylene from fossil fuels, chemical
plants is a major culprit
•
Synergistic effects (when combined
two are worse than each individually)
unpredictable
– White pine seedlings exposed to low
levels of O3 & SO2 individually are fine.
When combined cause death
– In alfalfa, O3 and SO2 together are
less harmful than individually.
•
Air pollutant effects on plants are
sometimes confused with insect
damage or other diseases.
Necrosis of
watermelon leaf
Necrotic lesions on lower
surface of potato leaves
3. Acid Deposition
Measuring Acid Rain
• Normal rain is slightly
acidic and has a pH
of about 5.0-5.6
• Any rainfall with a pH
value less than 5.0 is
defined as acid rain
Two Forms…
• Wet
Refers to acid
rain, fog, sleet,
cloud vapor and
snow.
• Dry
Refers to acidic
gases and
particles.
Increased Acidity
• Dry deposited gases and particles can
also be washed from trees and other
surfaces by rainstorms.
• The runoff water adds those acids to
the acid rain, making the combination
more acidic than the falling rain alone.
Compounds
Two main contributers to acid deposition:
• Sulfur Dioxide (SO2)
• Nitrogen Oxides (NOx)
– NO- nitric oxide (or nitrogen monoxide)
– NO2- nitrogen dioxide
– N2O- nitrous oxide
• 66% of all sulfur dioxides and 25% of all
nitrogen oxides comes from coal or oil electric
power plants. Most nitrogen oxides come from
cars
When gas pollutants e.g. sulfur
dioxide, nitrogen dioxide
dissolve in rain water, various
acids are formed.
CO2 + H2O
SO2 + H2O
NO2 + H2O



H2CO3 (carbonic acid)
H2SO4 (sulfuric acid)
HNO2 (nitrous acid) +
HNO3 (nitric acid)
Acidic Precipitation
Primary Pollutants
SO2
NO2
Secondary Pollutants
H2SO4
HNO2
sulfuric acid nitric acid
acidic precipitation
Fossil fuels
Power plants
Industrial emissions
Auto emissions
vegetation
direct toxicity
indirect health effects
soils
leaching of minerals
sediments
leaching aluminum
Acidic
Precipitation
Wind
Transformation to
sulfuric acid (H2SO4)
and nitric acid (HNO3)
Windborne ammonia gas
and particles of cultivated soil
partially neutralize acids and
form dry sulfate and nitrate salts
Sulfur dioxide (SO2)
Nitric oxide (NO)
and NO
Acid fog
Ocean
Dry acid
deposition
(sulfur dioxide
gas and particles
of sulfate and
nitrate salts)
Wet acid deposition
(droplets of H2SO4 and
HNO3 dissolved in rain
and snow)
Farm
Lakes in
deep soil
high in limestone
are buffered
Lakes in shallow
soil low in
limestone
become
acidic
Effects of Acid Rain
• The strength of the effects depend on many
factors
– How acidic the water is
– The types of fish, trees, and other living
things that rely on the water
– The chemistry and buffering capacity of the
soils involved
• limestone & basalt have high buffering capacity
• have high ANC (Acid Neutralizing Capacity)
Effects of Acid Rain
• Has a variety of effects, including damage to
forests and soils, fish and other living things,
materials, and human health.
• Also reduces how far and how clearly we can see
through the air, an effect called visibility
reduction.
• Effects of acid rain are most clearly seen in the
aquatic environments
• Most lakes and streams have a pH between 6
and 8
http://cica.indiana.edu/projects/Biology/movies.html
Buffering Capacity
• Acid rain primarily affects sensitive
bodies of water, which are located in
watersheds whose soils have a limited
“buffering capacity” (places that have
granite bedrock or soil for example)
• Lakes and streams become acidic when
the water itself and its surrounding soil
cannot buffer the acid rain enough to
neutralize it.
• In areas where buffering capacity is low,
acid rain also releases aluminum from
soils into lakes and streams
• aluminum is highly toxic to many
species of aquatic organisms.
– Can attach to fish gills causing suffocation
– Can release from soil particles & enter solutions taken up by
plants causing death
http://home.earthlink.net/~photofish/fish_photos/sw10_thumb.jpg
Effects on
Wildlife
• Some birds have left areas- no
fish, forests destroyed- less
nesting space
• Young of most species are more
sensitive to environmental
conditions than adults.
• At pH 5, most fish eggs cannot
hatch.
• At lower pH levels, some adult fish
die.
• Both low pH and increased
aluminum levels are directly toxic
to fish.
– Can also stress fish resulting in low
body weight, small size, less able
to compete for food, habitats,
reduced reproduction, increased
susceptibility to disease
Loons no
longer nesting
in Adirondack
Mtn lakes- too
acidic for fish
which they eat
Salmon populations have
decreased in Norway since 1950
due to acid rain. Red areas
show where populations have
declined.
Acid Rain and Forests
• Acid rain does not usually kill trees
directly.
• Instead, it is more likely to
– weaken trees by damaging their leaves
– limit the nutrients available to them
– expose them to toxic substances slowly
released from the soil.
Acid Rain & Forests
• Trees at higher
elevations can be
more effected
because of increased
exposure to acid fog
or acid cloud vapor
• As water evaporates
from leaf, acid
becomes more
concentrated, burning
the leaf tissue.
Effects of
Acid Rain
Great Smoky
Mountains, NC
Effects on Plant Nutrients
• Acidic water dissolves the
nutrients and helpful
minerals in the soil and
then washes them away
before trees and other
plants can use them to
grow.
• Acid rain also causes the
release of substances
that are toxic to trees and
plants, such as
aluminum, into the soil.
Effects on Property
• Many statues,
monuments, etc. made
from limestone (CaCO3),
marble or metal
• Acid rain can dissolve
rock or tarnish metal
• Expensive to restore,
refurbish, maintain
• Car manufacturers now
use acid-resistant paint at
a cost of $5.00 per new
vehicle