Chronic exposure to low levels of air pollutants can lead to respiratory illnesses, while acute exposure to high concentrations can cause disasters. The document discusses several case studies related to air pollution hazards: photochemical smog causes reduced visibility and respiratory issues; the 1952 London smog killed thousands due to coal smoke pollution; greenhouse gases like carbon dioxide contribute to global warming; and the Bhopal gas tragedy in 1984 exposed hundreds of thousands in India to toxic methyl isocyanate, killing thousands. Chronic nitrogen oxide exposure from silo filling can cause lung fibrosis in farmers. Air pollution has both human and environmental health impacts.

1. Hazards of air pollution
by
Dr. Eman Ezz Elsharkawy
Ph.D in forensic medicine and toxicology
Assiut University, Egypt

2. Acute
due to exposure to high concentration of pollutants lead to
many disasters .
Chronic
due to long term exposure to low levels of pollutants lead to
many respiratory aliments .
Health effects include both acute and chronic problems e.g.,
asthma, eye, possibly emphysema, nose and throat irritation,
and even death). The elderly and children are the most
susceptible.
Environmental effects as smog, green house effect and global
warming.
Hazards of air pollution

3. Smog
is an unhealthy mixture
of air pollutants
Case study (1)

4. Photochemical oxidants
• They arise from a series of complex
atmospheric reactions between hydrocarbons
and nitrogen oxides.
• Ozone is one of the most important
constituents of this group.
• The mixture of ozone, peroxyacetyl nitrate
(PAN), aldehydes and ketones form a haze
which is termed as photochemical smog ( it is
defined as a reddish brown haze in the
atmosphere).

5. Photochemical smog
• Photochemical smog is a
brown-air smog.
• It is formed through
light-driven chemical
reactions of primary
pollutants and normal
atmospheric compounds
that produce a mix
containing over 100
chemicals.
•This affects many cities.

6. Killer Smog
On December 5th, 1952, a dense smog enveloped the
city of London. From various news accounts, it
shutdown the city for four days, and was credited with
the death of more than 4,000 people during the fog,
and 8,000 afterwards.

8. Green house effects
Case study (2)

9. Carbon dioxide
• Carbon dioxide and water vapors are
responsible for maintaining earth's
temperature.
• About 50% of the solar energy is
absorbed by earth and rest by the
atmosphere after reflection.
• Carbon dioxide, water vapors and other
gases in atmosphere absorbed large part
of energy and emit it towards the ground
where it warms the surface of earth and
referred as natural green house effect.

10. • More is the production of carbon dioxide,
more is its concentration in the atmosphere,
more is the earth temperature.
• Carbon dioxide is the main green house gas
contributing about 49% toward green house
effect. Other gases are methane (18%), N2O
(6%), chlorofluorocarbons (14%) and others
(13%).

12. Global warming
Case study(3)

13. Global warming
• It is the observed rise in the average temperature of Earth's
climate system.
• Since 1971, 90% of the increased energy has been stored in
the oceans, mostly in the 0 to 700m region.
• Despite the oceans' dominant role in energy storage, the
term "global warming" is also used to refer to increases in
average temperature of the air and sea at Earth's surface.
• Since the early 20th century, the global air and sea surface
temperature has increased about 0.8 °C (1.4 °F), with about
two-thirds of the increase occurring since 1980.

14. Causes
• The most of global warming was being caused
by increasing concentrations of greenhouse
gases produced by human activities .
• The largest driver of global warming is carbon
dioxide (CO2) emissions from fossil fuel
combustion, cement production, and land use
changes such as deforestation.

15. • Human influence has been detected in
warming of the atmosphere and the ocean, in
changes in the global water cycle, in
reductions in snow and ice, in global mean sea
level rise, and in changes in some climate
extremes.

16. The effects of an increase in global temperature
• A rise in sea levels and a change in the amount and pattern
of precipitation, as well as a probable expansion of
subtropical deserts.
• Warming is expected to be strongest in the Arctic, with the
continuing retreat of glaciers, permafrost and sea ice.
• Other likely effects of the warming include more frequent
extreme weather events including heat waves, droughts and
heavy rainfall; ocean acidification; and species extinctions
due to shifting temperature regimes.
• Effects significant to humans include the threat to food
security from decreasing crop yields and the loss of habitat
from inundation.

17. Global warming
Reductions in snow and ice Retreat of glaciers, permafrost and
sea ice

18. Global warming
Species extinctions

19. Acute exposure to air pollutants
Lead to many
DISASTERSٍ

20. Bhopal gas tragedy due to methyle-
isocyanate.
Case study (4)

21. THE BHOPAL DISASTER
• Around 1 a.m. on Monday, the 3rd of December, 1984,
In the city of Bhopal, Central India, a poisonous vapour
burst from the tall stacks of the Union Carbide pesticide
plant.
• This vapour was a highly toxic cloud of methyl
isocyanate.
•2,000 died immediately
•300,000 were injured
•7,000 animals were injured, of which about one
thousand were killed.

22. THE POSSIBLE CAUSES
• A tank containing methyl isocyanate (MIC) leaked.
• MIC is an extremely reactive chemical and is used in
production of the insecticide carbaryl.
• The scientific reason for the accident was that water entered
the tank where about 40 cubic meters of MIC was stored.
• When water and MIC mixed, an exothermic chemical reaction
started, producing a lot of heat.
• As a result, the safety valve of the tank burst because of the
increase in pressure.
• It is presumed that between 20 and 30 tonnes of MIC were
released during the hour that the leak took place.
• The gas leaked from a 30 m high chimney and this height
was not enough to reduce the effects of the discharge.

26. Abortion due to cyanide
poisoning

27. Eye lesions

28. Eye lesion (corneal opacity)
due to cyanide poisoning

29. Congenital anomalies

30. Chronic exposure to air
pollutants
Lead to many
DESEASESٍ

31. Silo Filler’s Disease
case study (5)

32. Silo Filler’s Disease
• A disease caused by the inhalation of nitrogen
oxides
– Toxic levels of NO, NO2, N204 are all produced in
silos
– These gases are dense and settle in the chute and
base of the silo
– NO2 is brown and has an odor
– N204 is colorless and odorless
– When inhaled, they make nitric acid

34. Silo Filler’s Disease
• Clinical signs
– Mild exposure: cough, chest tightness
– Large exposure: vascular collapse, shock, death
• P/M lesions
- Lung fibrosis

35. Nitrogen oxides