atmospheric exposure

7/29/2019 atmospheric exposure

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Atmospheric Exposure

Dr. Mohammed Abdus Salam

[email protected]
mailto:[email protected]:[email protected]


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Atmospheric Composition


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Details of Atmospheric Composition

Nitrogen - 78.084%Oxygen - 20.95%

Argon - 0.934%

Carbon Dioxide - 0.036%

Neon - 0.0018%

Helium - 0.0005%

Methane - 0.00017%

Hydrogen - 0.00005%

Nitrous Oxide - 0.00003%

Ozone - 0.000004%


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Conventional Pollutants

U. S Clean Air Act designated seven major(Conventional or criteria) pollutants for whichmaximum ambient air levels area mandated-

Carbon Oxide

Sulfur oxide

Nitrogen oxide

Particulate Matter Metals and Halogen

Volatile Organic Compounds


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Emission from Motor Vehicles


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Emission From Motor Vehicles

Emission from motor vehicles have become a majorproblem as many consumers does not know aboutthe effects of motor vehicle emission.

According to US EPA, driving a car is the single mostpolluting thing and emits tons of pollutants into theair everyday.

In urban areas, motor vehicles are the single largestcontributors of ground level ozone, a majorcomponent of smog.


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Corbon Oxides

Predominant form of carbon in the air is

carbon dioxide.

- Increasing levels due to human activities

- Annual emission: 7-8 billion metric tons

Carbon monooxide is a colorless, orderless, toxicgas produced by imcomplete fuel combustion.

- Annual Emission: 1 billion metric tons


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Carbon Monoxide (CO)

Carbon monoxide poisoning is the most common

type of fetal air poisoning in many countries.

60% of carbon monoxide is caused by on road

vehicles.

It combines with hemoglobin to producecarboxyhemoglobin, which is ineffective for

delivering oxygen to bodily tissues.

Exposure of carbon monoxide damage the

human thinking capacity.


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Nitrogen Compounds

Nitrogen oxides are reactive gases formed

when nitrogen is heated above 650 degree

centrigates in the presence of oxygen, or

when nitrogen compounds are oxidized.

Annual Emission: 230 million metric tons


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NOx

Mononitrogen oxides NO and NO2 react with

ammonia, moisture and other compounds to formnitric acid vapor and related particles.

This small particles can penetrate deeply into

sensitive lung tissue and damage it, causepremature death in extreme cases.

Inhalation of this small particles may cause or

worsen respiratory diseases such as emphysema,bronchitis and also may aggravate existing heartdisease.


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Sulfur Compounds

Natural sources of sulfur in the atmosphere

include evaporation from sea spray, volcanic

fumes, and organic compounds.

Predominant form of anthropogenic sulfur is

sulfur dioxide from fossil fuel combustion.

Annual Emission: 114 million metric tons


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Sulfur Dioxide

Sources: Combustion of fuel containing

sulfur -- mostly coal and oil. Also producedduring metal smelting and other industrial

processes.


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Exposure limits (ppm) Health Effects

1-5 Threshold for respiratory response in healthy individuals upon exercise or deep breathing

3-5 Gas is easily noticeable. Fall in lung function at rest and increased airway resistance

5 Increased airway resistance in healthy individuals

6 Immediate irritation of eyes, nose and throat

10 Worsening irritation of eyes, nose and throat

10-15 Threshold of toxicity for prolonged exposure

20+ Paralysis or death occurs after extended exposure

150 Maximum concentration that can be withstood for a few minutes by healthy individuals

Health effects of respiratory exposure to sulpher dioxide


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Health Effects: SO2

High concentrations of sulfur dioxide (SO2) can

result in breathing problems with asthmatic

children and adults who are active outdoors.

Short-term exposure has been linked to wheezing,

chest tightness and shortness of breath.

Other effects associated with longer-term exposure

to sulfur dioxide, in conjunction with high levels of

particulate soot, include respiratory illness,

alterations in the lungs' defenses and aggravation of

existing cardiovascular disease.


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Environmental Effects of SO2

Sulfur dioxide is the major precursors of acid rain,

which has acidified soils, lakes and streams,

accelerated corrosion of buildings and monuments,

and reduced visibility.

Sulfur dioxide also is a major precursor of fine

particulate soot, which poses a significant healththreat.


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SOx and NOx pollution


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Particulate matter

Atmospheric aerosols solid or liquid

Respirable particles smaller than 2.5micrometers are among most dangerous.

Anthropogenic particulate emissions amount toabout 362 million metric tons annually.


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Particulate matter PM10 and PM2.5

The health effects of inhaling particulate matterhave been widely studied in humans and animalsand include asthma, lung cancer, cardiovascularissues, and premature death.

Because of tiny size, they can easily penetrate thedeepest part of the lungs.

About 1% of all PM10 and 2% of all PM2.5emissions came from the exhaust of on-road motorvehicles.


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Aggravated air pollution - industry


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Aggravated air pollution industry II


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Transportation related causes of air pollution


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Persistent Organic Pollutants

Humans are exposed daily to numerous chemicals

that can harm their health

Many harmful organic compounds are stable in the environment

(atmosphere, water, soil, food chain) for long periods Persistent Organic Pollutants (POPs)

- Characterised by stability, mobility, and bioaccumulation

- Harmful to human health and produce ecological damage

Stockholm Convention (May 2001): over 90 countries promisedto reduce or eliminate the production, use, and release of 12key POPsthe dirty dozen.


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12 Key POPsthe dirty dozen

The Dirty Dozen are produced for use as insecticides,

fungicides, chemical additives, or are inadvertently producedduring combustion. A biocide is a substance toxic to varyingdegrees to life forms:

Either synthesised deliberately to target and kill specific

organisms

general namepesticide

Or may be inadvertently produced

Pesticides: insecticide, bactericide,fungicide, herbicide

A pesticide designed to eliminate all types of living organisms iscalled afumigantor sterilant


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POP Use StructureAldrin Crop insecticide (corn, cotton)Chlordane Crop insecticide (vegetables, citrus,

cotton, potatoes)

DDT

(dichloro-diphenyl-

trichloroethane)

Crop insecticide (cotton)

Dieldrin Crop insecticide (cotton, corn)Endrin Crop insecticide (cotton, grains)

Heptachlor Insecticide (termites and soil insects)

Hexachlorobenzene Fungicide for seed treatmentMirex Insecticide (termites, fire ants)Toxaphene Insecticide (livestock, crops)PCBs Industrial chemical (paint and plastic

additive)

Dioxins Unintentionally produced duringcombustion

Furans Unintentionally produced duringcombustion


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DDT

Chemical stability: DDT degrades to DDE

(dichlorodiphenyldichloroethene)

DDE is less toxic than DDT but more resilient in the

environment


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DDT

DDT has a broad spectrum of activity. It was banned in several

countries in the 1970s because of ecological considerations

Still used extensively to reduce insect-transmitted diseases:

yellow fever, sleeping sickness, typhus, malaria and others

Persistent in the environment and resistant to complete

degradation by microorganisms

Photodegradation can occur


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DDTEnvironmental Levels and

Human Exposure

Air: when DDT is sprayed, any that fails to reach its target can drift

away. Vaporisation from treated fields can be detected for more

than 6 months after application. It can drift up to 1000km

Environmental levels:

Nonagricultural areas: < 12.4 ng m-3

Agricultural communities: 122 ng m-3

Communities with anti-mosquito programmes: up to 8.5 g m-3


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DDTEnvironmental Levels and Human

Exposure

Human exposure: Can affect the nervous system.Acute

intoxication by DDT can lead to symptoms such as nausea,

vomiting, paraesthsia, dizziness, confusion, tremors and in

severe cases convulsionsAll the symptoms are rare

No evidence that DDT has reproductive or teratogenic effects

All epidemiological studies in humans have indicated that DDT isnot carcinogenic


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atmospheric exposure