Chapter 2 Air pollution

1. CHAPTER 2: Air Pollution
Prepared by: Shaheen Sardar
COURSE TITLE: Environmental issues of textile
industry

2. INTRODUCTION
• Air pollution is the introduction of chemicals,
particulate matter or biological materials that
cause harm or discomfort to humans or other
living organisms, or cause damage to the
natural environment or built environment,
into the atmosphere.

3. INTRODUCTION

4. INTRODUCTION
• Sulfurous smog is caused by combustion of
fossil fuels, especially coal, in stationary
sources such as plants and smelters.
• CO, oxides of nitrogen, and various VOCs swirl
around in atmosphere reacting with each
other and with sunlight to form
Photochemical smog.

5. INTRODUCTION
• Much of the work on air pollution in the last
few decades has centered on a small set of six
substances, called Criteria Pollutants” that
have been identified as contributors to both
sulfurous and photochemical smog problems.
We will focus on these Criteria Pollutants.

6. INTRODUCTION
• More recently, attention has been shifting
towards the characterization and control of a
growing list of especially hazardous air
pollutants, many of which we are exposed to
in our homes and workplaces, where we
spend roughly 90% of our time.
• Modest improvements in indoor air quality
can improve public health as much as major
reductions in the traditional outdoor sources.

8. OVERVIEW OF EMISSIONS
• There are many sources of the gases and
particulate matter that pollute our
atmosphere.
• Substances that are emitted directly into the
atmosphere are called primary pollutants.
Examples are Nitrogen oxides and
hydrocarbons emitted when fuels are burned.

9. OVERVIEW OF EMISSIONS
• Substances that are created by various
physical processes and chemical reactions that
take place in the atmosphere are called
secondary pollutants. Example is ground level
ozone (O3) that is created when those
chemicals react with each other in the
atmosphere.

10. OVERVIEW OF EMISSIONS
• Primary pollutants enter the atmosphere as a
result of combustion, evaporation, or grinding
and abrasion.
• Volatile substances such as gasoline, paints,
and cleaning fluids enter the atmosphere by
evaporation.

11. OVERVIEW OF EMISSIONS
• Dust kicked up when land is plowed and
asbestos fibers that flake off of pipe insulation
are examples of grinding and abrasion.
• Automobile exhaust emissions and power
plant stack gases are created during
combustion.

12. OVERVIEW OF EMISSIONS
• Combustion accounts for the majority of
emissions.
• Combustion is the gases and particulate
matter released when fuels are burned.
• Complete combustion of a pure hydrocarbon
fuel such as methane CH4 is given below:
• CH4 + 2O2 → CO2 + 2H2O

13. OVERVIEW OF EMISSIONS
• If temperature of combustion is not high
enough, or there is not enough oxygen
available, or if the fuel is not given enough
time to burn completely, then following
reaction takes place. Where, (HC) stands for
hydrocarbons.
• CH4 + O2 → mostly (CO2 + 2H2O) + traces of
[CO +(HC)]

14. OVERVIEW OF EMISSIONS
• Air is 78% N2 and 21% O2, when temperature
of combustion is very high; some of N2 reacts
with O2 in air to form various nitrogen oxides.
Following reaction takes place.
• Air (N2 + O2) +Heat → Thermal NOX

15. OVERVIEW OF EMISSIONS
• If fuel is not pure, then following reaction
takes place.
• Fuel (H, C,S, N, Pb, ash) +air (N2 + O2) →
Emissions (CO2, H2O, CO, NOX, SOX, Pb,
Particulates) + ash

16. OVERVIEW OF EMISSIONS
• Secondary pollutant ground level ozone (O3) is
formed as a result of following reaction.
• VOCs + NOX + Sunlight → Photochemical Smog
(O3 + etc.)

17. OVERVIEW OF EMISSIONS
• There are two categories of sources of air
pollution, Mobile Sources and Stationary
Sources.
• Mobile Sources: Highway vehicles
(automobiles and trucks) and other modes of
transportation (railroads, aircraft, farm
vehicles and “boats and ships”.

18. OVERVIEW OF EMISSIONS
• Stationary Sources: There are following three
categories of Stationary sources.
• (i) Stationary fuel combustion: Electric power
plants and industrial energy systems.
• (ii) Industrial Processes: Metal processing,
petroleum refineries, and other chemical and
allied product manufacturing.
• (iii) Miscellaneous sources:

19. OVERVIEW OF EMISSIONS
• Following table and figures show emissions of
six air pollutants with respect to mobile
sources and stationary sources.
CO Pb NOX VOCs PM10 SOX
Transport 77% 33% 45% 36% 22% 3%
Fuel combustion 6% 10% 50% 3% 46% 88%
Industrial 7% 57% 4% 57% 32% 9%
Miscellaneous 10% 0% 1% 4% 0% 0%

20. OVERVIEW OF EMISSIONS
77%
6%
7%
10%
CO Transport
Fuel combustion
Industrial
Miscellaneous

21. OVERVIEW OF EMISSIONS
33%
10%
57%
Pb Transport
Fuel combustion
Industrial
Miscellaneous

22. OVERVIEW OF EMISSIONS
45%
50%
4% 1%
NOX
Transport
Fuel combustion
Industrial
Miscellaneous

23. OVERVIEW OF EMISSIONS
36%
3%
57%
4%
VOCs Transport
Fuel combustion
Industrial
Miscellaneous

24. OVERVIEW OF EMISSIONS
22%
46%
32%
PM10 Transport
Fuel combustion
Industrial
Miscellaneous

25. OVERVIEW OF EMISSIONS
3%
88%
9%
SOX Transport
Fuel combustion
Industrial
Miscellaneous

26. CRITERIA POLLUTANTS (SIX MOST
IMPORTANT POLLUTANTS):
• (1) Carbon Monoxide (CO):
• It is produced when carbonaceous fuels are
burned under less than ideal conditions.
• Incomplete combustion(yielding CO instead of
CO2) results when any of the following four
variables are not kept sufficiently high:
• (1) Oxygen supply, (2) Combustion
temperature, (3) Gas residence time at high
temperature, and (4) Combustion Chamber
Turbulence.

27. (1) Carbon Monoxide (CO)
• 77% of total CO emissions are from
transportation sector.
• All CO in urban areas comes from motor
vehicles.
• CO interferes with the blood’s ability to carry
oxygen from the lungs to the body’s organs and
tissues.
• When inhaled, it readily binds to hemoglobin in
the blood stream to form (COHb)
carboxyhemoglobin.

28. (1) Carbon Monoxide (CO)
• Hemoglobin has greater affinity for CO than O2.
• With less oxygen brain function is effected,
Heart rate increases, Physiological effects can
be noted, affects brain ability to perceive and
react, dizziness, headache, fatigue, and
impaired judgment, loss of consciousness and
death.

29. (1) Carbon Monoxide (CO)
• Tobacco smoke also raises CO levels.
• COHb is removed from the bloodstream when
clear air is breathed.

30. CRITERIA POLLUTANTS (SIX MOST
IMPORTANT POLLUTANTS):
• (2) Oxides of Nitrogen:
• 7 oxides of Nitrogen are known, NO, NO2, NO3,
N2O, N2O3, N2O4, and N2O5.
• Only two are important air pollutants, Nitric
Oxide (NO) and Nitrogen dioxide (NO2).
• There are following two sources of NOX, when
fossils fuels are burned.
• Thermal NOX and Fuel NOX.

31. (2) Oxides of Nitrogen
• 7 oxides of Nitrogen are known, NO, NO2, NO3,
N2O, N2O3, N2O4, and N2O5.
• Only two are important air pollutants, Nitric
Oxide (NO) and Nitrogen dioxide (NO2).
• There are following two sources of NOX, when
fossils fuels are burned.
• Thermal NOX and Fuel NOX.

32. (2) Oxides of Nitrogen
• Thermal NOX is created is created when
nitrogen and oxygen in the combustion air are
heated to a high enough temperature (about
1000K) to oxidize the nitrogen.
• Thermal NOX, results from the oxidation of
nitrogen compounds that are chemically bound
in the fuel molecules themselves.
• Almost all NOX emissions are in the form of NO,
which is a colorless gas and has less effect on
health.

33. (2) Oxides of Nitrogen
• NO can oxidize to NO2, which can irritate the
lungs, cause bronchitis and pneumonia, lower
resistance to respiratory infections.
• NOX can react with volatile organic compounds
(VOCs) in the presence of sunlight to form
photochemical oxidants that have adverse
health effects.

34. (2) Oxides of Nitrogen
• NO2 reacts with hydroxyl radical (OH) in
atmosphere to form nitric acid (HNO3), which
corrodes metal surfaces and contributes to the
acid rain problem.
• Modifications to the combustion process that
can reduce emissions of CO tend to make the
NOX problem worse, and vice versa.
• A reduction in NOX emissions is harder than
reductions in other criteria pollutants.

35. CRITERIA POLLUTANTS (SIX MOST
IMPORTANT POLLUTANTS):
• (3) Photochemical Smog and ground level
Ozone:
• Volatile organic compounds (VOCs) include
unburnt hydrocarbons that are emitted from
tailpipes and smoke attacks when fossil fuels
are not completely combusted along with
gaseous hydrocarbons that enter the
atmosphere when solvents, fuels and other
organics evaporate.

36. (3) Photochemical Smog and ground
level Ozone:
• Volatile organic compounds (VOCs) include
unburnt hydrocarbons that are emitted from
tailpipes and smoke attacks when fossil fuels
are not completely combusted along with
gaseous hydrocarbons that enter the
atmosphere when solvents, fuels and other
organics evaporate.

37. (3) Photochemical Smog and ground
level Ozone:
• 1/3 of VOCs emissions result from transport
sources.
• 2/3 of VOCs emissions result from industrial
sources.
• Less than 2% of VOCs result from fossil fuel
combustion in power plants and industrial
boilers.

38. (3) Photochemical Smog and ground
level Ozone:
• When oxides of nitrogen, VOCs, and sunlight
come together, they can initiate a complex set
of reactions that produce a number of
secondary pollutants known as photochemical
oxidants. Ground level Ozone (O3) is the most
abundant of the photochemical oxidants.
• VOCs + NOX + Sunlight → Photochemical Smog
(O3 + etc.)

39. (3) Photochemical Smog and ground
level Ozone:
• Ground level Ozone (O3) is harmful to our
health. But stratospheric Ozone protects our
health by shielding us from ultraviolet radiation
from the sun.
• It causes materials and vegetables damage.
• It causes respiratory effects such as coughing,
shortness of breath, headache, chest tightness
and eye, nose, and throat irritation.

40. CRITERIA POLLUTANTS (SIX MOST
IMPORTANT POLLUTANTS):
• (4) Particulate matter:
• Atmospheric particulate matter consists of any
dispersed matter, solid, or liquid.
• Size range from 0.005μm diameter to 100μm
(roughly the size of a human hair).
• Term “aerosol” is used for any tiny particulate,
liquid, or solid, dispersed in the atmosphere.

41. (4) Particulate matter
• Solid particles are called “dust” if they are
caused by grinding or crushing operations.
• Solid particles are called “fumes” if they are
formed when vapors dense.
• Liquid particles may be called “mist” or “fog”.
• Carbon particles that result from incomplete
combustion are called smoke and soot.

42. (4) Particulate matter
• Particles have very irregular shapes.
• Large particles that enter the respiratory system
can be trapped by the hairs and lining of the
nose. (Driven out by cough or sneeze).
• Smaller particles can be captured by hair like
cilia in the respiratory system. (Removed by
swallowing or spitting).

43. (4) Particulate matter
• Sources are fuel combustion, industrial
processing and transportation.
• Transportation sources are emissions from
buses and trucks.
• 95% of particulate emissions are from wild fires,
wind-driven soil erosion, dust from croplands,
construction, mining activities, and the
constant abrasion of paved and unpaved
roadways.

44. (4) Particulate matter
• The bulk smoke from diesel engines and smoke
stacks consists solid particles made up of “carbon
atoms fused in benzene rings” can irritate lungs.
• Of greater concern is a class “Poly nuclear aromatic
hydrocarbons consist of fused benzene rings”. Its
sources are tobacco smoke, motor vehicle exhaust,
the char on charcoal, broiled food, and smoke from
wood and coal combustion.

45. (4) Particulate matter
• Most dangerous is a substance called
benzo[a]pyrene (Bap), consists of five fused
rings. It is a category-A human carcinogen
known to cause lung and kidneys cancer.
• Aerosols consisting (SO4) contribute to
respiratory distress, degradation of materials,
and major cause of reduced visibility.

46. (4) Particulate matter
• Particulates aggravate existing respiratory and
cardiovascular disease and damage lung tissue,
and some are carcinogenic.
• Tens of thousands of premature deaths are
caused each year in US due to inhaled particles.

47. CRITERIA POLLUTANTS (SIX MOST
IMPORTANT POLLUTANTS):
• (5) Oxides of Sulfur:
• Sulfur dioxide is highly water soluble than any
other criteria pollutant. When it is inhaled it is
absorbed in moist passages of the upper
respiratory tract, the nose and upper airways,
where it does less long term damage.
• When Sulfur oxides reach far deeper into the
lungs, the combination of particulate matter and
sulfur oxides can act synergistically to cause excess
mortality. (50,000 premature deaths, 2% of total
deaths per year in the US and Canada).

48. (5) Oxides of Sulfur
• Sulfur oxides can damage trees.
• Sulfurous pollutants can discolor paint, corrode
metals, and cause organic fibers to weaken.
• Airborne Sulfates reduce visibility and discolor
the atmosphere.
• Prolong exposure to Sulfates cause serious
damage to building marble, limestone and
mortar, as the carbonates (e.g. limestone,
CaCO3) in these materials are replaced by
sulfates.
• CaCO3 +H2SO4 → CaSO4 + CO2 + H2O.

49. (5) Oxides of Sulfur
• The calcium Sulfate (Gypsum, CaSO4) produced by
this reaction is water soluble and easily washed
away leaving a pitted, eroded surface.
• In US, 90% of 22 million tons/ year of sulfurous
emissions are the result of fossil fuel combustion in
stationary sources. 85% of that is emitted from
electric utility power plants (16 million tons/ year).
• 3% sulfurous emissions come from highway
vehicles.
• Non combustion sulfurous emissions are from
petroleum refining, copper smelting, and cement
manufacture.

50. CRITERIA POLLUTANTS (SIX MOST
IMPORTANT POLLUTANTS):
(6) Lead:
• Most lead emissions from motor vehicles
burning gasoline containing the antiknock
additive tetraethyl lead Pb (C2H5) 4.
• Ambient (outdoor) lead levels tend to be high in
the vicinity (nearness) of industrial facilities
such as metal smelters and plants that
manufacture lead acid batteries.
• Lead is emitted into the atmosphere in the form
of inorganic particulates.

51. (6) Lead
• Air borne lead may affect human populations by
direct inhalation. People living near highways or
metal processing plants are at greatest risk.
• In door source of lead is chipped and flaking particles
of lead-based paints.
• Most human exposure to lead is from inhalation.
• Lead can also be ingested after airborne lead is
deposited onto soil, water, and food crops such as
leafy vegetables and fruits.
• Lead poisoning can cause aggressive, hostile, and
destructive behavioral changes as well as learning
disabilities, seizures, severe and permanent brain
damage, and even death.

52. TOXIC AIR POLLUTANTS
• These are carcinogenic, teratogenic,
neurotoxic, which cause reproductive
dysfunction, or which are acutely are
chronically toxic.
• There are hundreds of such chemicals.
• Examples are asbestos, benzene, beryllium,
coke-oven emissions, inorganic arsenic,
mercury, radionuclides, and vinyl chloride.

53. AIR POLLUTION IN BIG CITIES
• Principal source is motor vehicles.
• Leaded fuels are burned.
• High %age of the vehicles is diesel-powered
trucks and buses with no emission controls.
• Many streets are unpaved.
• Traffic congestion, which intensifies emissions,
is overwhelming.

54. AIR POLLUTION IN BIG CITIES
• The resulting concentrations of Pb, CO, NOX,
O3 and suspended particulate matter (SPM)
are higher.
• Coal-fired power plants and other industrial
facilities within city limits and levels of SOX,
NOX and particulate matter are high.
• Combustion of coal and biomass fuels for
cooking and heating leads to extremely high
pollutant concentrations indoors, where many
people spend most of their time.

55. INDOOR AIR QUALITY
• Combustion that takes place inside of homes
and other buildings to cook, heat water, and
provide space heating and cooling can
produce elevated levels of CO, Nitrogen
oxides, hydrocarbons, and respirable
particulates.
• Cigarette smoke emits CO, benzene, acrobin,
and other aldehydes, and particulates, as well
as about 4000 other chemicals.

56. INDOOR AIR QUALITY
• Some photocopying machines emit ozone.
• Building materials such as particle board,
plywood, urea-formaldehyde foam insulation,
and various adhesives emit formaldehyde.
• Chipped and peeling paint containing lead
becomes air borne toxic dust.
• A long list of VOCs is emitted from house hold
cleaning products, paints, carpeting, and a
variety of other chemicals we use in our
homes.

57. INDOOR AIR QUALITY
• Some pollutants are unique to the indoor
environment such as following;
• Asbestos: Used for fireproofing and insulation.
• Radon gas: Seeps out of the houses and
collects in houses.
• Biological Pollutants: Such as house dust
mites, fungi, and other microorganisms.

58. INDOOR AIR QUALITY
ENVIRONMENTAL TOBACCO SMOKE:
• Tobacco Smoke contains over 4000 chemicals,
including more than 40 that cause cancer in
humans or animals. Many chemicals are
strong respiratory irritants.
• Smokers inhale “mainstream smoke”.

59. INDOOR AIR QUALITY
ENVIRONMENTAL TOBACCO SMOKE:
• Sidestream smoke, emitted from smoldering
cigarettes, mixed with smoke exhaled by
smoker is known as “Environmental tobacco
smoke (ETS) or secondhand smoke”.
• Breathing air with ETS is called “involuntary or
passive smoking”.
• ETS causes lung cancer and other disorders.

60. INDOOR AIR QUALITY
ASBESTOS:
• Asbestos is a common name for a group of
naturally occurring fibrous silicate minerals
that are made up of thin but strong durable
fibers. Because of its tensile strength and heat
resistant properties, asbestos has been used
extensively in building materials such as
ceilings, insulation and tiles, automobile
clutch and transmission parts and heat
resistant fabrics.

61. INDOOR AIR QUALITY
ASBESTOS:
• Asbestos is a mineral and is relatively stable in
the environment unless they are
disturbed. Natural weathering or upon
damage or disturbance of asbestos-containing
products, the microscopic fibers become
airborne and can be inhaled into the lungs or
ingested with contaminated food where they
can cause significant health problems.

62. Asbestos

63. Asbestos

64. INDOOR AIR QUALITY
Asbestos:
• It is Hazardous air pollutants. Asbestos is
dangerous when it is crushed, crumbled or
disturbed because fibers can be released into
the air.
• It is used to be a common building material
found in structural fireproofing, heating-
system insulation, floor and ceiling tiles,
roofing felts and shingles.

65. INDOOR AIR QUALITY
Asbestos:
• Used in consumer products such as fireplace
gloves, and certain hair dryers.
• If these materials damage, microscopic fibers
may be dispersed into the indoor air
environment.
• Inhalation of these fibers can lead to diseases
including asbestosis, lung cancer and
mesothelioma.

66. INDOOR AIR QUALITY
ASBESTOS:
• Asbestos exposure along with tobacco smoke
elevates the lung cancer risk by approximately
fivefold.

67. INDOOR AIR QUALITY
RADON: It is second leading cause of lung
cancer after smoking.
• Sources are diffusion from soil, ground water
and building materials such as brick, concrete,
and tiles.
• Radon itself is inert but its short-lived decay
products-Polonium, lead, and bismuth-are
chemically active and easily become attached
to inhaled particles that can lodge in the lung.

68. INDOOR AIR QUALITY
RADON:
• Indoor air can be exchanged with outdoor air by
any combination of following three mechanisms.
• Radon is a naturally-occurring, invisible and
odorless radioactive gas. One in 15 American
homes contains high levels of radon. Millions of
Americans are unknowingly exposed to this
dangerous gas. Radon gas causes more deaths
every year than fires and carbon monoxide
combined.

70. INDOOR AIR QUALITY
• (1) Infiltration: Natural air exchange, when doors
and windows are closed. Air exchange happens
by leakage through various cracks and holes in
building.
• (2) Natural Ventilation: Air exchange, when
windows or doors are purposely opened to
increase air circulation.
• (3) Forced Ventilation: Air exchange using fans or
blowers by mechanical handling systems.