effects of air pollutants effects on human health effects on vegetation and animals effects on...
TRANSCRIPT
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
Sources and Sinks
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.
• 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.
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)
Regional particle deposition
Particle Size conventions
• Inhalable fraction (<100 μm AED)
Can be breathed into nose or mouth
• Thoracic fraction (<25 μm AED)
Can penetrate head airways and enter lung airways
• Respirable fraction (<10 μm AED)
Can penetrate beyond terminal bronchioles to gas exchange region
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
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.
Molecular View ofCarbon Monoxide Poisoning
EOS
Impact of air pollution on humans
Health effects data can be obtained by
• Clinical
• Epidemiological
• Toxicological studies
AIR POLLUTION EFFECTS
Dose Response Relationship
Dose-response curve
No threshold type dose-response curve
resp
onse
dose
Threshold type dose-response curve
Threshold value: under which no adverse effect was observed
)()((int timedrateremovalinhalationbyrateakeDosageHarmful
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
Injury. - Generally, pollution injury first appears as leaf injury. Spots between the veins, leaf margin discoloration, and tip burns are common.
Crossection of a leaf
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.
Leafs are important because of its functions
• Photosynthesis accomplished by chloroplasts
6CO2+6H2O C2H12O6+6O2
• Transpiration: Movement of water from the root system up to the leaves. Nutrient movement and cooling
• Respiration:Oxidation of carbonhydrates, energy producing process.
• C2H12O6+6O2 6CO2+6H2O
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.
typical of Peroxyacetyl Nitrate (PAN) creates a glazy bronzing on the underside of newly expanded potato leaves.
PAN injury
SO2 Damage: SO2 causes an interveinal necrosis. Note the green veins in these samples.
Ozone damage Note stippling symptoms on leaves
Fluorine Damage: Note the marginal necrosis (this is similar to salt damage).
Effects on materials
Effects on metals
• Rusting
• Corrosion due to moisture, temperature and pollutants
• Alteration of electrical properties
Effects on stone
• Discoloration
• Blackening
• gypsum formation
• Cracking
Gypsum formationCaCO3+H2SO4+2H2O CaSO4.2H2O+H2CO3
CaCO3+H2CO3 Ca(HCO3)2
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.
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
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.
Kualo Lumbur,2005, Malasia
Emergency was announced on august 2005. API was greater than 500
• 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
Gas to particle conversion occurs via
• Absorption: gas goes into solution of liquid phase (solubility dependent)
• Nucleation: thermodynamically stable clusters formed.
• Condensation:collisons between a gaseous molecule and an esisting aerosol.
Long term effetcs on the planet
• Global warming
• Ozone hole
The Ozone LayerThe 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
The Ozone Layer
Of all the human activities that affect the ozone layer, release of chlorofluorocarbons (CFCs) is thought to be the most significant
EOS
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)
CFCs and ozone
• CFCs have long residence time in the atmosphere
FCCl3+hv CCl2F+ Cl
Cl +O3 ClO +O2
ClO +O Cl +O2
O3+O 2O2
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
EOS
The main strategy for countering human contributions to possible global warming is to curtail the use of fossil fuels
There are many natural sources that contribute significantly to “greenhouse” gas production that cannot be controlled by humans
The Greenhouse Effect
EOS
Acid rain• Formation HNO3 and H2SO4 in water
droplets due to SO2 and NOx
www.epa.org
Deposition of pollutants
volatilization
sorption
desorptiondissolution
Dry deposition
Deposition of particles
aerosols with bound HOCs
Washout of vaporsWashout of
particles Wet deposition
Water droplets
HOC vapors
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
Rain sampling