abs

1. • Primary & Secondary Air Pollutants.
• EPA Based Troposhere Disturbance.

2. PREPARED BY :-
• Zainab Mohammad
• Rashida Mohammad
• Khalid Sultan
• Muhammad Nabeel
PREPARED FOR :-
 Miss Sadia
NUML KARACHI
BS – ENG 5TH SEMESTER (Brig-01)
(EVENING)

3.  Air pollution- the introduction of chemicals, particulate matter, or
microorganisms into the atmosphere at concentrations high enough to
harm plants, animals, and materials such as buildings, or to alter
ecosystems.
 Typically refers to the troposphere.

4.  Sulfur Dioxide
 Nitrogen Oxides
 Carbon Oxides
 Particulate Matter
 Volatiles Organic Compounds
 Ozone
 Lead
 Mercury

5.  Volcanoes
 Lightning
 Forest fires
 Plants

6.  On-road vehicles
 Power plants
 Industrial processes
 Waste disposal

7. • Primary pollutants – those released directly into the
lower atmosphere, i.e. CO, SO 2
• Secondary pollutants – those that are formed by the
combination of primary pollutants in the atmosphere. For
example, acid rain is produced from the combination of
sulfur oxides (SO2 and SO3) and water vapor.
• Other examples: HNO3, H2O2, H2SO4. PANs, NO3-, SO4-

8.  Primary pollutants- polluting compounds that come
directly out of the smoke-stack, exhaust pip, or
natural emission source.
 Examples: CO, CO2, SO2, NOx, and most
suspended particulate matter.

9.  Secondary pollutants- pollutants that have
undergone transformation in the presence of
sunlight, water, oxygen, or other compounds.
 Examples: ozone, sulfate and nitrate

10. • CFCs (chlorofluorocarbons)
• Invented in the 1930s
• Used as coolants, propellants, in fire extinguishers, and aerosols
• Known to cause depletion of stratospheric ozone
• Ozone depletion can lead to
• Eye cataracts
• Skin cancer
• Weakened immune systems
• Decrease in productivity of marine and terrestrial ecosystems
• PCBs (polychlorinated biphenyls)
• A group of 209 toxic, oily, synthetic chlorinated hydrocarbon
compounds that can be biologically amplified in food chains/webs
• Neurotoxin
• Sources: pesticides, hydraulic fluids, transformers, wood
treatments, paint, plastic, roofing materials,
lubricants………………..

11. • Some primary air pollutants may react with one
another or with other chemicals in the air to form
secondary air pollutants.
Figure 19-3

12. • The sequence of events which result in acid deposition
formation are
1. Combustion releasing SO2 and NOx
2. Secondary pollutants are formed
3. Dissociation of pollutants
4. Deposition of ions on vegetation or soil

13. • Normal rainfall has a pH of 5.7
• Typical rainfall in eastern US has a pH of 4.6
• In general, acid rain has harmful effects for terrestrial
ecosystems when it falls below a pH of 5.6
• Linked to NOx and SO2
• Fish kills; damages or kills aquatic life
• Stunts plant growth and makes them susceptible to
disease
• Damages statues, buildings and car finishes

14. • Humans have added pollutants to the air throughout
history (early man’s fire, Roman’s smelting
lead);[anthropogenic]. However, large-scale production
of pollutants began with the Industrial Revolution.
• Today, idling cars add most air pollution………
• Once air pollutants have entered the atmosphere, they
may be
1. Removed with precipitation
2. Transformed through chemical reactions
3. Transported on air currents and wind
4. Trapped by topography and inversions

15. • Industrial (gray) smog
• Results from incomplete combustion of fossil fuels such as coal,
oil and natural gas
• Releases CO, CO2, soot, sulfur and Hg
• Reacts with oxygen and sunlight
• Photochemical (brown) smog
• Formed from reactions involving nitrogen oxides
• These reactions also produce acid rain and tropospheric ozone

17. Indoor Air Pollution

18. Fig. 19-11, p. 453

19. Factoids
• Asbestos, radon-222, formaldehyde and
cigarette smoke – 4 most dangerous
• Dust mites, cockroach droppings, mold &
mildew – contributors to asthma

20. Radon
• 55% of our exposure to radiation comes from radon
• Strong carcinogen
• colorless, tasteless, odorless gas
• formed from the decay of uranium-238
• found in nearly all soils, igneous rock
• levels vary geographically
• Remediation includes sealing or venting areas

21. (From: http://www.epa.gov/iaq/radon/zonemap.html)
Zone pCi/L
1 >4
2 2 - 4
3 <2

22. Radon: How it Enters Buildings
• Cracks in solid floors
• Construction joints
• Cracks in walls
• Gaps in suspended floors
• Gaps around service pipes
• Cavities inside walls
• The water supply
http://www.epa.gov/iaq/radon/pubs/citguide.html#howdoes

23. Radon: Reducing the Risks
• Sealing cracks in floors and walls
• Simple systems using pipes
and fans for ventilation

24. 1. Removing sulfur from coal
2. Burning low-sulfur coal
3. Convert coal to liquid or gaseous fuel (cleaner burning)
4. Shifting to less polluting fuels
5. Use emission-control devices
• Wet-scrubbers – decrease SO2 from coal-burning power plants
• Electrostatic precipitators – remove particulates from
smokestacks
• Baghouse filters
• Cyclone separators

25. • It is formed from the reaction of O with O2 in the
presence of ultraviolet light
• Without interference, there is a steady state of ozone
being created and destroyed
• The ozone absorbs UV-B rays and decomposes into O2
and O
• It is a closed loop cycle

26. • Widespread use of certain chemicals has reduced ozone
levels in the stratosphere, which allows for more harmful
ultraviolet radiation( UV-A and UV-B) to reach the earth’s
surface.
• To reverse ozone depletion, we must stop producing
ozone-depleting chemicals and adhere to the
international treaties that ban such chemicals.

27. • Damaging UV-A and UV-B radiation
• Increase eye cataracts and skin cancer
• Impair or destroy phytoplankton- Antarctic
• base of food web
• Loss of removal of carbon dioxide from the atmosphere –
worsening global warming

28. Fig. 19-20, p. 524
Stepped Art
Effects of ozone depletion

29. Fig. 19-E (2), p. 526

31. • The Environmental Protection Agency
(EPA) was established in December
1970 by the executive order of President
Richard Nixon. It is an agency of the
United States federal government
whose mission is to protect human and
environmental health. Headquartered in
Washington, D.C., the EPA is
responsible for creating standards and
laws promoting the health of individuals
and the environment.

32. • The troposphere is the lowest
layer of Earth's atmosphere.
Most of the mass (about 75-80%)
of the atmosphere is in the
troposphere. Most types of
clouds are found in the
troposphere, and almost all
weather occurs within this layer.