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Atmospheric Exposure
Dr. Mohammed Abdus Salam
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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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