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