air pollution, types of pollutants, types of pollution, wet and dry methods of controlling particulate and gaseous air pollutants

2. INTRODUCTION
Ms. G. Tejasri
Faculty of Engineering Sciences,
NIT AP – 534101.

3. World’s Top 5 Air Pollution disasters
1. Bhopal gas tragedy (India)
2. Chernobyl disaster (Russia)
3. Seveso disaster (Italy)
4. London smog (England, UK)
5. Grand canyon of Colorado (USA)

4. Bhopal gas tragedy
• Duration :2nd and 3rd of December, 1984.
• Reason: Methyl Iso cyanate (MIC).
• The Union Carbide pesticide plant in Bhopal India leaked
MIC. This tragedy was a result of water entering a tank
containing around 42 tons of MIC, creating a chemical
reaction that raised temperatures to over 200°c, increasing the
pressure making the tank vent the toxic gas which caught in
the Northwesterly wind passing over Bhopal.
• To this day, groundwater and soil in areas even 3km away
from the factory contains almost 40 times more pesticides than
Indian standards. The soil and water also contain toxic metals
like lead, mercury, arsenic, cadmium and chromium.

5. Chernobyl disaster (Russia)
• On 26 April 1986, reactor four suffered a catastrophic
power increase, leading to explosions in its core. This
dispersed large quantities of radioactive fuel and core
materials into the atmosphere and ignited the combustible
graphite moderator. The burning graphite moderator
increased the emission of radioactive particles, carried by
the smoke, as the reactor had not been encased by any kind
of hard containment vessel. The accident occurred during an
experiment scheduled to test a potential safety emergency
core cooling feature, which took place during a normal
shutdown procedure.
• The battle to contain the contamination and avert a greater
catastrophe ultimately involved over 5,00,000 workers and
cost an estimated 18 billion rubles.

6. The burnt nuclear plant

7. London smog
• Duration : December 5 to December 9, 1952
• Death toll : approximately 12,000 people
• Reason: When a thick fog engulfed London it mixed
with black smoke emitted from homes and factories
to create a deadly smog.

9. Seveso disaster
• On midday of July 10, 1976 an explosion occurred in a TCP
(2,4,5-trichlorophenol) reactor in a chemical company in
Meda, Italy. A toxic cloud escaped into the atmosphere
containing high concentrations of TCDD (tetra chloro di-
benzo dioxin), a highly toxic form of dioxin. Downwind
from the factory the dioxin cloud polluted a densely
populated area of 6 km long and 1 km wide, immediately
killing many animals. A neighboring municipality that was
highly affected is called Seveso. The accident was named
after this village. The dioxin cloud affected a total of 11
communities.
• The most remarkable feature of the Seveso accident was
that local and regional authorities had no idea the plant was
a source of risk.

10. Grand canyon of Colorado

11. • Regional haze is the "dirty-looking" air that
prevents us from seeing clearly or very far
through the air. It especially affects our
enjoyment of national parks, such as the Grand
Canyon.
• Sulfate particles, formed by the reaction of
sulfur dioxide (SO2) from power plants and
other sources in the atmosphere, account for 50
to 70 percent of the visibility reduction.

12. Effects on Human
Chloracne

13. Damage to vegetation
Necrosis: Acid rain damage to plants

14. The red forest

15. Effects on animals
Piglet affected due to radiations A unique kitten with single eye

16. Damage to art treasures

17. Damage to Art treasures
Great art treasures suffering from stone leprosy or stone cancer

18. Accidents due to visibility problem

19. Visibility problem spoiling the
natural scenic beauty

20. Conclusion
• These situations are like alarms for
other countries to avoid similar kind
of mishaps.

22. Air pollution (AP)
• As per IS :4167-1966, the presence in ambient
atmospheres of substances, generally resulting
from the activity of man, in sufficient
concentration , present for a sufficient time and
under circumstances such as to interfere with
comfort, health or welfare of persons or with
reasonable use or enjoyment of property is
called “AIR POLLUTION”

23. Threshold Limiting Value (TLV)
• The maximum concentration to
which healthy adult workers may be
exposed 8 hours a day for 5
continuous days a week without
adverse effects.
• E.g. : o.2 ppb and 5 ppm are the for
desirable and threshold limits of SOx
respectively.

24. Classification of Air
Pollutants
Based on
chemical
composition
Based on origin
Based on state
of matter

25. Classification based on chemical
composition
Organic
• Compounds of carbon and
hydrogen.
• e.g. aldehydes, ketones,
ether, alcohols etc.
Inorganic
• Found in polluted
atmosphere
• e.g. NOx, SOx, CO, HF,
HCl, CO2 etc.

26. Classification based on origin
Primary pollutants
• Primary pollutants are
substances that are directly
emitted into the atmosphere
from sources.
• E.g.: Carbon compounds,
such as CO, CO2, CH4, and
VOCs. Nitrogen
compounds, such as NO,
N2O, and NH3. Sulfur
compounds, such as H2S
and SO2.
Secondary pollutants
• Secondary pollutants are not
directly emitted from sources,
but instead form in the
atmosphere from primary
pollutants (also called
“Precursors”).
• E.g.: NO2 and HNO3 formed
from NO, Ozone (O3) formed
from photochemical reactions
of nitrogen oxides and VOCs,
Smog, Sulfuric acid droplets
formed from SO2 and nitric
acid droplets formed from
NO2.

27. Formation of Secondary pollutants

28. Formation of Photochemical Smog

29. Formation of acid rains

30. Classification based on state of
matter
Particulate
• Finely divided solids and
liquids
• Under normal conditions, they
settle out of atmosphere.
• May contain materials with
toxic or carcinogenic effects.
• Extremely small particles can
become lodged in lungs
• E.g. : smoke, fog, fume, mist,
aerosol, dust
Gaseous
• They are form less fluids
that completely occupy the
space into which they are
released and behave like air.
• They don't settle out of
atmosphere.
• E.g. : Hydrocarbons, NH3,
HF, CO, SOx and NOx

31. Particulate matter
SPM 10
• Coarse particles (2.5–10
micrometers) deposited in
the upper respiratory tract
and large airways
• Smoke, dirt and dust
from factories, farming, and
roads, mold, spores, and
pollen
SPM 2.5
• Fine particles (< 2.5
micrometers) may reach
terminal bronchioles and
alveoli
• Toxic organic compounds,
heavy metals

33. Particulate pollutants
• Dust – It contains particles of the size ranging from 1 to 200 m. These are
formed by natural disintegration of rock and soil or by the mechanical processes of
grinding and spraying.
• Smoke – Small gas borne particles of the size ranging from 0.01 to 1 m resulting
from combustion which can be liquid or solid. Can have different colors
depending on the nature of material burnt.
• Fumes – Particles formed by condensation, sublimation , or chemical reaction.
These are solid particles of the size ranging from 0.1 to 1 m
• Mist – It is made up of liquid droplets generally smaller than 10 m which are
formed by condensation in the atmosphere or are released from industrial
operations.
• Fog – It is the mist in which the liquid is water and is sufficiently dense to obscure
vision.
• Aerosol – Under this category are included all air-borne suspensions either solid or
liquid; these are generally smaller than 1 m . Dispersion of microscopic solid or
liquid particles in gaseous media.

34. Gaseous Pollutants
• Oxides of Sulphur (SOx, H2SO3)
• SO2 is the most important pollutant emitted and is oxidized slowly to sulphur
trioxide. This intern rapidly combines with moisture in the atmosphere to form
sulphuric acid. Both SO2 and SO3 are relatively quickly washed out of the
atmosphere by rain or settle out as aerosols.
• Oxides of Nitrogen (NOx, N2O)
• Among the seven oxides of nitrogen, N2O, NO and NO2 are formed in appreciable
quantities in the atmosphere.
• Carbon Monoxide (CO) and CO2
• CO is the single largest pollutant in the urban atmosphere and has strong affinity
towards hemoglobin of the blood stream. The rate of oxidation of CO to CO2 is
very slow. The main sources of CO in the urban air are smoke and exhaust fumes of
burning gas, coal or oil.
• Lighter Hydrocarbons (HCs)
• The gaseous and volatile liquid hydrocarbons are of particular interest as air
pollutants. The hydrocarbons in air by themselves alone cause no harmful effects.
These are responsible for the production of secondary pollutants in the presence of
sunlight.

35. Sources of AP
Natural/ geogenic
1. Of natural occurrence
2. Contribute to the composition of
earth’s atmosphere.
3. Causes more pollution
4. Uncontrollable
5. Equally distributed all over the
world reach a sink such as ocean
or the soil.
6. The atmosphere can cleanse
itself from the pollutants given
sufficient time
• e.g. volcanic eruptions, sea salt
sprays, SPM, RPM, radio active
materials, atmospheric reactions.
Artificial/ Anthropogenic/ Man
made
1. Occurs due to manmade activities
2. Causes less pollution
3. Controllable
4. Gets distributed based on type and
size of the industry, development.
5. The emission of these pollutants is
at such massive rates
6. They overwhelm the capacity of
the environment to cleanse itself.
• e.g. pollution from industrial stacks,
aircrafts, fumes from vehicles(CO,
SOx and NOx )

36. Adverse effects
• May be divided into acute and chronic effects.
• Acute: High concentration for shorter duration.
• Chronic: lower concentration for higher
durations (prolonged periods).

37. Effects on human beings
S.No.: Pollutant Health effects
1. HCHO -Odors cause irritation to eye, skin, respiratory
system
-Effects Central Nervous System (CNS)
-Causes Cardiovascular problems
2. NH3 -Corrosive to mucous membrane
-Causes damage to eye and respiratory tract
3. SO2 -Air starvation when mixed with body fluids , forms
sulfuric acid which is a strong and corrosive acid.
4. CO -When inhaled, combines with blood and forms carb-
oxy hemoglobin
-Asphyxiation
-Very poisonous
-Persons look pale in color

38. Effects on human beings
S.No.: Pollutant Health effects
5. NOx -When inspired, even minute concentration causes
chronic irritation of respiratory tract, head ache
-Loss of appetite
-Causes corrosion of teeth
6. O3 -At high concentration, smells like chlorine
-Poisonous even at low concentrations
-Leads to asthma attacks
7. H2S -Causes headache, sleeplessness, eye pain,
conjunctivitis
-In high concentration, can lead to blockage of
oxygen transfer, acts as cell poison and damage nerve
tissues.
8. PM -Repiratory track problems
-Clinges to skin, hair and get adsorbed into body
-Causes silicosis, lung cancer diseases.

39. Effects on human beings
S.No.: Pollutant Health effects
9. Lead - Lead is neurotoxin whose poisoning results in
convulsions, delirium, coma, severe and irreversible brain
damage and death.
10. Cadmium - Cigarette smoking constitutes a major source for cadmium
accumulation in the body.
- It inhibits the performance of certain enzymes thereby
producing hypertension in humans. Also causes
cardiovascular diseases when exposed to fumes or oxides of
cadmium.
11. Mercury - Effects of mercury poisoning include neurological
damage, chromosomal aberrations and even death.
- Higher levels of mercury can build up in the fetus without
the mother showing any signs of illness. The effects are
congenital birth defects or the death of the fetus
12. Hydro carbons and
Photochemical Oxidants
-At the concentrations usually found in the urban air, causes
no adverse effects on human health.
-The oxidant produced in photochemical smog causes
irritation to the nose, throat and causes chest constriction.

40. Effects on Vegetation
• Leaf structure damage is visible incase of
vegetation.
• The pollutants try to enter through stomata and
diffuse to the surface of the cells within the leaf
causing damage to palisade and spongy
mesophyll.
• The damages are necrosis (dead areas), chlorosis
(loss or reduction chlorophyll), epinasty
(downward curvature of the leaf).
• Chemicals such as arsenic and fluorides when
deposited on the leaves can poison animals.

41. stomata

42. Effect on materials
• Particulates such as dust and fumes can
damage the exposed surfaces because of their
abrasive nature
• The most notorious pollutant responsible for
metallic corrosion is SO2.
• Ozone is also very reactive substance and
causes the cracking of synthetic rubbers at the
levels of 0.01 to 0.02 ppm.

43. Particulate Collection Mechanism
 Gravity Settling
 Centrifugal Impaction
 Inertial Impaction
 Direct Interception
 Diffusion
 Electrostatic Effects

44. General Methods For Control Of
Particulate Emissions
Gravity and Momentum
collectors:
 Settling chambers
 Baffle chambers
Centrifugal Collectors:
 Cyclones
 Mechanical centrifugal
collectors
Fabric Filters:
 Bag houses
 Fabric collectors
Electrostatic Precipitators :
 Tubular
 Plate
Wet Collectors :
 Spray towers
 Impingement scrubbers
 Wet cyclones
 Packed towers
 Mobile bed scrubbers

45. • Gravitational settling chambers

47. Venturi Scrubber

50. • Electrostatic Precipitator

51. Assignment
• Rank of Bhopal gas tragedy amongst world’s
disasters.
3
• Hiroshima and Nagasaki Atomic bomb disaster
– a case study.
• Most polluted city in India is ?
Delhi

52. INDOOR AIR QUALITY

55. INDOOR AIR QUALITY
• Refers to the air quality within and
around buildings and structures, especially as
it relates to the health and comfort of building
occupants
• NASA calls it Sick Building Syndrome.

56. Common Indoor Air Pollutants
• Molds
• Pollen
• Dander from pet fur
• Secondhand smoke
• Formaldehyde
• Fumes emitted by imported drywall
• Carbon monoxide that comes from burning
propane, other gases and fuels, and charcoal
• Household products such as cleaners and
pesticides

57. Preventive measures
• Open windows or run air conditioning or ventilation
systems to bring in fresh air.
• Clean to get rid of dust and pet fur.
• Fix water leaks to help keep mold away.
• Use bug spray only when absolutely necessary.
• Do not smoke inside.
• If you see or smell mold, clean it up with detergent and
water or a mix of no more than 1 cup of bleach mixed with
1 gallon of water. Never mix bleach with ammonia.
• If you smell gas, do not light any flames or sparks and leave
the building right away.

58. Air Quality Index (AQI)
• It is an indicator of air quality, based on air pollutants
that have adverse effects on human health and the
environment. The pollutants are ozone, fine particulate
matter, nitrogen dioxide, carbon monoxide, sulphur
dioxide and total reduced sulphur compounds.
• As the AQI increases, an increasingly large percentage
of the population is likely to experience increasingly
severe adverse health effects
• It can lead to suffering from lung diseases such as
asthma. It can also cause headaches, dry eyes, nasal
mucus, nausea and tiredness.

59. Standards of Air quality index

60. Each category corresponds to a
different level of health concern
• Good. The AQI value for your community is between 0 and 50. Air
quality is satisfactory and poses little or no health risk.
• Moderate. The AQI is between 51 and 100. Air quality is
acceptable; however, pollution in this range may pose a moderate
health concern for a very small number of individuals. People who
are unusually sensitive to ozone or particle pollution may experience
respiratory symptoms.
• Unhealthy for Sensitive Groups. When AQI values are between
101 and 150, members of sensitive groups may experience health
effects, but the general public is unlikely to be affected.
- Ozone: People with lung disease, children, older adults and people
who are active outdoors are considered sensitive and therefore at
greater risk
- Particle pollution: People with heart or lung disease, older adults,1
and children are considered sensitive and therefore at greater risk.

61. • Unhealthy. Everyone may begin to experience
health effects when AQI values are between 151
and 200. Members of sensitive groups may
experience more serious health effects.
• Very Unhealthy. AQI values between 201 and
300 trigger a health alert, meaning everyone may
experience more serious health effects.
• Hazardous. AQI values over 300 trigger health
warnings of emergency conditions. The entire
population is even more likely to be affected by
serious health effects