Effects of Air Pollutants

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Effects of Air Pollutants

• Effects on human health
• Effects on vegetation and animals
• Effects on materials and structure
• Long term effects on the planet
• Risk Assessment

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Sources and Sinks
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Effects on human health

• Pollutants enter body via inhalation, ingestion
  and dermal contact
• TOTAL BODY BURDEN the way a trace material
  accumulates in the human system
• Chemicals can be stored in the body
  compartments blood, urine, soft tissue,
  hair,teeth and bone.
• Body can eliminate the trace material over a
  period of few hours to days or longer
• Accumulation results when the material is much
  more rapidly stored than eliminated.

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• Pollutants can be stored in the blood, urine,
  soft tissue, hair and bone.
• Effect on human health mostly depends on the
  quantity of pollutants and the rate of removal.

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Human respiratory system

• Primary function to deliver O2 to the
  bloodstream and remove CO2 from body.
• Respiratory system may be divided into 3 as
• Nasal (nose and mouth)
• Tracheobronchial (trachea and bronchial tubes)
• Pulmanory (bronchia and alveolar sacs)

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Regional particle deposition
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Particle Size conventions

• Inhalable fraction (lt100 µm AED)
• Can be breathed into nose or mouth
• Thoracic fraction (lt25 µm AED)
• Can penetrate head airways and enter lung airways
• Respirable fraction (lt10 µm AED)
• Can penetrate beyond terminal bronchioles to gas
  exchange region

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Particle and gas behavior in the lung

• Gases Solubility dependent
• Particle behavior depends on aerodynamic
  characteristics
• Very large particles, nasal openings allow
• Smaller particles deposits in the trachebronchial
  and pulmanory regions.
• Very small particles penetrates into alveolar
  membrane

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CO and the human body

• Ambient CO
• Indoor CO
• In the body O2 is moved for biochemical oxidation
  and CO2 (waste) removed.
• Hemoglobin-O2
• Hemoglobin-CO2

This complex is stong enough to transport gases
in the circulatory system. But not strong enough
to prevent delivery to lungs and cells.
CO forms a much more stable complex with
hemoglobin(Hemoglobin-CO, COHb), so it reduces
the number of free hemoglobins for transport of
CO2 and O2.
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Molecular View ofCarbon Monoxide Poisoning
EOS
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Impact of air pollution on humans

• Health effects data can be obtained by
• Clinical
• Epidemiological
• Toxicological studies

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AIR POLLUTION EFFECTS

• Dose Response Relationship

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Dose-response curve
No threshold type dose-response curve
Threshold type dose-response curve
response
dose
Threshold value under which no adverse effect
was observed
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Effects on vegetation and animals

• Injury vs damage
• Injury An observable alteration in the plant
  when exposed to air pollution
• Damage An economic or aesthetic loss due to
  interference with the use of a plant

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Injury. - Generally, pollution injury first
appears as leaf injury. Spots between the veins,
leaf margin discoloration, and tip burns are
common.
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Crossection of a leaf
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Two ways of pollutant entrance to plant

• Direct way Through stomates which open and close
  to allow air through the interior parts
• Indirect way Through the root system. Pollutants
  deposit in soil and water and these pollutants
  were taken by the roots of the plant.

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Leafs are important because of its functions

• Photosynthesis accomplished by chloroplasts
• 6CO26H2O C2H12O66O2
• Transpiration Movement of water from the root
  system up to the leaves. Nutrient movement and
  cooling
• RespirationOxidation of carbonhydrates, energy
  producing process.
• C2H12O66O2 6CO26H2O

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Ozone InjuryOzone, the major component of
oxidants is formed by the action of sunlight on
products of fuel combustion and can be moved to
nearby growing areas by wind. Symptoms vary
depending on the concentration of ozone in the
air and the length of exposure, Ozone injury
occurs on the most recently emerged leaves.
Typical ozone injury may not be evident on leaves
exposed to a mixture of pollutants. Symptoms
differ in different areas of the province.
foliage with flecking "pepper spotting" injury
typical of ozone injury.Huntsville, Ontario.
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PAN injury
typical of Peroxyacetyl Nitrate (PAN) creates a
glazy bronzing on the underside of newly expanded
potato leaves.
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SO2 Damage  SO2 causes an interveinal necrosis.
  Note  the green veins in these samples.
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Ozone damage Note stippling symptoms on leaves
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Fluorine Damage  Note the marginal necrosis
(this is similar to salt damage).
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Effects on materials

• Effects on metals
• Rusting
• Corrosion due to moisture, temperature and
  pollutants
• Alteration of electrical properties

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Effects on stone

• Discoloration
• Blackening
• gypsum formation
• Cracking
• Gypsum formation
• CaCO3H2SO42H2O CaSO4.2H2OH2CO3
• CaCO3H2CO3 Ca(HCO3)2

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These damaged areas seem to receive rain or rain
runoff and seem to be formed by sulfur dioxide
uptake, in the presence of moisture, on the stone
surface. Subsequent conversion of the sulfur
dioxide to sulfuric acid results in the formation
of a layer of gypsum on the marble surface.
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Effects on the atmosphere, visibility degradation

• Visibility is reduced due to light scattering or
  absorption by the gases and particulates.
• Scattering is wavelength dependent.
• Longer wavelenths scatter less.
• Light absorption by NO2
• Absorbs shorter blue causing red lights to be
• seen

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Atmospheric haze

• Reduced visibility caused by the presence of fine
  particles or NO2 in the atmosphere
• Particles are in the range of 0.1-1.0 um. The
  major component of atmospheric haze is sulfate,
  nitrate, graphitic material, fly ash and
  aerosols.
• Primary and secondary particulate matters cause
  haze.

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Kualo Lumbur,2005, Malasia Emergency was
announced on august 2005. API was greater than 500
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• Primary particulate matter Combustion processes
  emit PM less than 1um size.
• Large quantities of NO2 and SO2 are also emitted.
• Secondary particulate matter gas to particle
  conversion.
• Gaseous molecules transformed to liquid and solid
  particles

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Gas to particle conversion occurs via

• Absorption gas goes into solution of liquid
  phase (solubility dependent)
• Nucleation thermodynamically stable clusters
  formed.
• Condensationcollisons between a gaseous molecule
  and an esisting aerosol.

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Long term effetcs on the planet

• Global warming
• Ozone hole

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The Ozone Layer
The ozone layer is a band of the stratosphere
about 20 km thick, centered at an altitude of
about 25 to 30 km
Ozone absorbs ultraviolet (UV) radiation, and the
ozone layer thus protects life on Earth
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The Ozone Layer
Ozone is produced in the upper atmosphere in a
sequence of two reactions involving free radical
oxygen atoms
O2 hv ? O O O2 O (M) ?
O3 (M)
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CFCs and ozone

• CFCs have long residence time in the atmosphere
• FCCl3hv CCl2F Cl
• Cl O3 ClO O2
• ClO O Cl O2
• O3O 2O2

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CO2 and the Greenhouse Effect
The greenhouse effect occurs when radiant energy
is retained in the atmosphere and warms it
Some atmospheric scientists think that global
warming is already under way
There are many natural sources that contribute
significantly to greenhouse gas production that
cannot be controlled by humans
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The Greenhouse Effect
EOS
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Acid rain

• Formation HNO3 and H2SO4 in water droplets due to
  SO2 and NOx

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www.epa.org
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Deposition of pollutants
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ACID RAINHow do we measure acidity of the rain

• Rain water has a natural pH of 5.5 (less than 7)
• Collect rain water
• Measure pH

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Rain sampling