Short Notes: Environmental Engineering - Module IV | Short Notes for Civil Engineering - Civil Engineering (CE) PDF Download

 Page 1


Module-IV
A ir pollution
Unit of measurement
Concentrations of air pollutants are commonly expressed asthe mass of pollutant per Unit 
volume of air mixture, as mg/m3 , pg/m3, ng /m3
Concentration of gaseous pollutants may also be expressed as volume of pollutant per million 
volumes of the air plus pollutant mixture (ppm) where 1ppm= 0.0001 % by volume. It is 
sometimes necessary to convert from volumetric units to mass per unit volume and vice versa.
The relation ship between ppm and mg/m3 depends on the gas density, which in turn depends 
on:™Temperature, Pressure, Molecular weight of the pollutant
The following expression can be uses to convert of between ppm and mg/m3 at any temperature 
or pressure.
mg/m3 = 273 X PPM X molecular w t X pressure 
22.4 X temperature
Simply multiply the calculated value of mg/m3 by 1000 to obtain pg/m3 . The constant 22.4 is the 
volume in liter occupied by 1 mole of an ideal gas at standard concentration (0°c and 1 atm.). 
One 14 mole of any substance is a quantity of that substance whose mass in grams numerically 
equals its molecular weight
Sources and Classification of pollutants
Air pollution may be defined as any atmospheric condition in which certain substances are 
present in such concentrations that they can produce undesirable effects on man and his 
environment. These substances include gases (SOx, NOx, CO, HCs, etc) particulate matter 
(smoke, dust, fumes, aerosols) radioactive materials and many others. Most of these 
substances are naturally present in the atmosphere in low (background) concentrations and are 
usually considered to be harmless. A particular substance can be considered as an air pollutant 
only when its concentration is relatively high compared with the back ground value and causes 
adverse effects.
Air pollution is a problem of obvious importance in most of the world that affects human, plant 
and animal health. For example, there is good evidence that the health of 900 million urban 
people suffers daily because of high levels of ambient air sulfur dioxide concentrations. Air 
pollution is one of the 6 most serious environmental problems in societies at all level of
Page 2


Module-IV
A ir pollution
Unit of measurement
Concentrations of air pollutants are commonly expressed asthe mass of pollutant per Unit 
volume of air mixture, as mg/m3 , pg/m3, ng /m3
Concentration of gaseous pollutants may also be expressed as volume of pollutant per million 
volumes of the air plus pollutant mixture (ppm) where 1ppm= 0.0001 % by volume. It is 
sometimes necessary to convert from volumetric units to mass per unit volume and vice versa.
The relation ship between ppm and mg/m3 depends on the gas density, which in turn depends 
on:™Temperature, Pressure, Molecular weight of the pollutant
The following expression can be uses to convert of between ppm and mg/m3 at any temperature 
or pressure.
mg/m3 = 273 X PPM X molecular w t X pressure 
22.4 X temperature
Simply multiply the calculated value of mg/m3 by 1000 to obtain pg/m3 . The constant 22.4 is the 
volume in liter occupied by 1 mole of an ideal gas at standard concentration (0°c and 1 atm.). 
One 14 mole of any substance is a quantity of that substance whose mass in grams numerically 
equals its molecular weight
Sources and Classification of pollutants
Air pollution may be defined as any atmospheric condition in which certain substances are 
present in such concentrations that they can produce undesirable effects on man and his 
environment. These substances include gases (SOx, NOx, CO, HCs, etc) particulate matter 
(smoke, dust, fumes, aerosols) radioactive materials and many others. Most of these 
substances are naturally present in the atmosphere in low (background) concentrations and are 
usually considered to be harmless. A particular substance can be considered as an air pollutant 
only when its concentration is relatively high compared with the back ground value and causes 
adverse effects.
Air pollution is a problem of obvious importance in most of the world that affects human, plant 
and animal health. For example, there is good evidence that the health of 900 million urban 
people suffers daily because of high levels of ambient air sulfur dioxide concentrations. Air 
pollution is one of the 6 most serious environmental problems in societies at all level of
economic development. Air pollution can also affect the properties of materials (such as rubber), 
visibility, and the quality of life in general. Industrial development has been associated with 
emission to air of large quantities of gaseous and particulate emissions from both industrial 
production and from burning fossil fuels for energy and transportation.
When technology was introduced to control air pollution by reducing emissions of particles, it 
was found that the gaseous emissions continued and caused problems of their own. Currently 
efforts to control both particulate and gaseous emissions have been partially successful in much 
of the developed world, but there is recent evidence that air pollution is a health risk even under 
these relatively favorable conditions.
In societies that are rapidly developing sufficient resources may not be invested in air pollution 
control because of other economic and social priorities. The rapid expansion of the industry in 
these countries has occurred at the same time as increasing traffic from automobiles and trucks, 
increasing demands for power for the home, and concentration of the population in large urban 
areas called mega cities. The result has been some of the worst air pollution problem in the 
world.
In many traditional societies, and societies where crude household energy sources are widely 
available, air pollution is a serious problem because of inefficient and smoky fuels used to heat 
buildings and cook. This causes air pollution both out door and indoors. The result can be lung 
disease, eye problems, and increased risk of cancer.
The quality of air indoors is a problem also in many developed countries because buildings were 
built to be airtight and energy efficient. Chemicals produced by heating and cooling systems, 
smoking and evaporation from buildings materials accumulate indoors and create a pollution 
problem.
The health effects of ambient air pollution have been difficult to document with certainty until 
recent years. This is because of methodological problems in assessing exposure, other factors 
that cause respiratory disease (such as cigarette smoking, respiratory tract infections, and 
allergies), and the difficulty of studying such effects in large populations.
Recently, however, a series of highly sophisticated and convincing studies from virtually every 
continent have demonstrated that air pollution has a major effect on human health. Respiratory 
symptoms are the most common adverse health effects from air pollution of all types. Following 
Table presents a summary of major health effects thought to be caused by community air 
pollution. Respiratory effects of air pollution, particularly complicating chronic bronchitis, may 
place an additional strain on the heart as well.
Page 3


Module-IV
A ir pollution
Unit of measurement
Concentrations of air pollutants are commonly expressed asthe mass of pollutant per Unit 
volume of air mixture, as mg/m3 , pg/m3, ng /m3
Concentration of gaseous pollutants may also be expressed as volume of pollutant per million 
volumes of the air plus pollutant mixture (ppm) where 1ppm= 0.0001 % by volume. It is 
sometimes necessary to convert from volumetric units to mass per unit volume and vice versa.
The relation ship between ppm and mg/m3 depends on the gas density, which in turn depends 
on:™Temperature, Pressure, Molecular weight of the pollutant
The following expression can be uses to convert of between ppm and mg/m3 at any temperature 
or pressure.
mg/m3 = 273 X PPM X molecular w t X pressure 
22.4 X temperature
Simply multiply the calculated value of mg/m3 by 1000 to obtain pg/m3 . The constant 22.4 is the 
volume in liter occupied by 1 mole of an ideal gas at standard concentration (0°c and 1 atm.). 
One 14 mole of any substance is a quantity of that substance whose mass in grams numerically 
equals its molecular weight
Sources and Classification of pollutants
Air pollution may be defined as any atmospheric condition in which certain substances are 
present in such concentrations that they can produce undesirable effects on man and his 
environment. These substances include gases (SOx, NOx, CO, HCs, etc) particulate matter 
(smoke, dust, fumes, aerosols) radioactive materials and many others. Most of these 
substances are naturally present in the atmosphere in low (background) concentrations and are 
usually considered to be harmless. A particular substance can be considered as an air pollutant 
only when its concentration is relatively high compared with the back ground value and causes 
adverse effects.
Air pollution is a problem of obvious importance in most of the world that affects human, plant 
and animal health. For example, there is good evidence that the health of 900 million urban 
people suffers daily because of high levels of ambient air sulfur dioxide concentrations. Air 
pollution is one of the 6 most serious environmental problems in societies at all level of
economic development. Air pollution can also affect the properties of materials (such as rubber), 
visibility, and the quality of life in general. Industrial development has been associated with 
emission to air of large quantities of gaseous and particulate emissions from both industrial 
production and from burning fossil fuels for energy and transportation.
When technology was introduced to control air pollution by reducing emissions of particles, it 
was found that the gaseous emissions continued and caused problems of their own. Currently 
efforts to control both particulate and gaseous emissions have been partially successful in much 
of the developed world, but there is recent evidence that air pollution is a health risk even under 
these relatively favorable conditions.
In societies that are rapidly developing sufficient resources may not be invested in air pollution 
control because of other economic and social priorities. The rapid expansion of the industry in 
these countries has occurred at the same time as increasing traffic from automobiles and trucks, 
increasing demands for power for the home, and concentration of the population in large urban 
areas called mega cities. The result has been some of the worst air pollution problem in the 
world.
In many traditional societies, and societies where crude household energy sources are widely 
available, air pollution is a serious problem because of inefficient and smoky fuels used to heat 
buildings and cook. This causes air pollution both out door and indoors. The result can be lung 
disease, eye problems, and increased risk of cancer.
The quality of air indoors is a problem also in many developed countries because buildings were 
built to be airtight and energy efficient. Chemicals produced by heating and cooling systems, 
smoking and evaporation from buildings materials accumulate indoors and create a pollution 
problem.
The health effects of ambient air pollution have been difficult to document with certainty until 
recent years. This is because of methodological problems in assessing exposure, other factors 
that cause respiratory disease (such as cigarette smoking, respiratory tract infections, and 
allergies), and the difficulty of studying such effects in large populations.
Recently, however, a series of highly sophisticated and convincing studies from virtually every 
continent have demonstrated that air pollution has a major effect on human health. Respiratory 
symptoms are the most common adverse health effects from air pollution of all types. Following 
Table presents a summary of major health effects thought to be caused by community air 
pollution. Respiratory effects of air pollution, particularly complicating chronic bronchitis, may 
place an additional strain on the heart as well.
Disease or How air pollution
condition may affect it Associated factors
Eye irritation Specific effect o f photochemical 
oxidants, Possibly aldehydes or 
peroxyacetyl Nitrates; particulate
Susceptibility differs
matter (fly ash} as a Foreign body
Acute bronchitis Direct irrigative effects o f SOs. Cigarette smoking may
soot and Petrochemical pollution have a more ihan 
Additive interaction
Chronic bronchitis Aggravation (increase in Cigarette smoking.
Frequency or Severity) o f cough 
or sputum Associated with a ny 
sort o f pollution
occupation
Asthma Aggravation from respiratory usually pre-existing
irritation, Possibly on respiratory allergy
reflex basis or airway hyperactivity
Headache Carbon m onoxide sufficient Smoking m ay also increase
To lead to more than 10% carboxyhaemoglobin but not
carboxy haemoglobin Enough to lead to headache
Lead toxicity Add to body burden C lose proxim ity to lead
source; Exposure at home
Air pollution is associated with increased risk of death from heart disease and lung disease, 
even at levels below those known to be acutely toxic to the heart. Mucosal irritation in the form 
of acute or chronic bronchitis, nasal tickle, or conjunctivitis is characteristic of high levels of air 
pollution, although individuals vary considerably in their susceptibility to such effects.
The eye irritation is particularly severe, in the setting of high levels of particulates (which need to 
be in the respirable range described and may be quite large soot particles) or of high 
concentrations of photochemical oxidants and especially aldehydes.
There is little evidence to suggest that community air pollution is a significant cause of cancer 
except in unusual and extreme cases. However, emissions from particular sources may be 
cancer-causing. Examples of cancer associated with community air pollution may include point- 
source emissions from some smelters with poor controls that release arsenic, which can cause 
lung cancer. Central nervous system effects, and possibly learning disabilities in children, may 
result from accumulated body burdens of lead, where air pollution contributes a large fraction of 
exposure because of lead additives in gasoline.
These health effects are better characterized for populations than for individual patients. 
Establishing a relationship between the symptoms of a particular patient and exposure to air 
pollution is more difficult than interpreting the likely health effects on an entire community. It is 
important to understand that these pollutants are seasonal in their pattern. Both ozone and 
sulfates, together with ultra fine particulates, tend to occur together during the summer months 
in most developed areas. Ozone, oxides of nitrogen, aldehydes, and carbon monoxide tend to
Page 4


Module-IV
A ir pollution
Unit of measurement
Concentrations of air pollutants are commonly expressed asthe mass of pollutant per Unit 
volume of air mixture, as mg/m3 , pg/m3, ng /m3
Concentration of gaseous pollutants may also be expressed as volume of pollutant per million 
volumes of the air plus pollutant mixture (ppm) where 1ppm= 0.0001 % by volume. It is 
sometimes necessary to convert from volumetric units to mass per unit volume and vice versa.
The relation ship between ppm and mg/m3 depends on the gas density, which in turn depends 
on:™Temperature, Pressure, Molecular weight of the pollutant
The following expression can be uses to convert of between ppm and mg/m3 at any temperature 
or pressure.
mg/m3 = 273 X PPM X molecular w t X pressure 
22.4 X temperature
Simply multiply the calculated value of mg/m3 by 1000 to obtain pg/m3 . The constant 22.4 is the 
volume in liter occupied by 1 mole of an ideal gas at standard concentration (0°c and 1 atm.). 
One 14 mole of any substance is a quantity of that substance whose mass in grams numerically 
equals its molecular weight
Sources and Classification of pollutants
Air pollution may be defined as any atmospheric condition in which certain substances are 
present in such concentrations that they can produce undesirable effects on man and his 
environment. These substances include gases (SOx, NOx, CO, HCs, etc) particulate matter 
(smoke, dust, fumes, aerosols) radioactive materials and many others. Most of these 
substances are naturally present in the atmosphere in low (background) concentrations and are 
usually considered to be harmless. A particular substance can be considered as an air pollutant 
only when its concentration is relatively high compared with the back ground value and causes 
adverse effects.
Air pollution is a problem of obvious importance in most of the world that affects human, plant 
and animal health. For example, there is good evidence that the health of 900 million urban 
people suffers daily because of high levels of ambient air sulfur dioxide concentrations. Air 
pollution is one of the 6 most serious environmental problems in societies at all level of
economic development. Air pollution can also affect the properties of materials (such as rubber), 
visibility, and the quality of life in general. Industrial development has been associated with 
emission to air of large quantities of gaseous and particulate emissions from both industrial 
production and from burning fossil fuels for energy and transportation.
When technology was introduced to control air pollution by reducing emissions of particles, it 
was found that the gaseous emissions continued and caused problems of their own. Currently 
efforts to control both particulate and gaseous emissions have been partially successful in much 
of the developed world, but there is recent evidence that air pollution is a health risk even under 
these relatively favorable conditions.
In societies that are rapidly developing sufficient resources may not be invested in air pollution 
control because of other economic and social priorities. The rapid expansion of the industry in 
these countries has occurred at the same time as increasing traffic from automobiles and trucks, 
increasing demands for power for the home, and concentration of the population in large urban 
areas called mega cities. The result has been some of the worst air pollution problem in the 
world.
In many traditional societies, and societies where crude household energy sources are widely 
available, air pollution is a serious problem because of inefficient and smoky fuels used to heat 
buildings and cook. This causes air pollution both out door and indoors. The result can be lung 
disease, eye problems, and increased risk of cancer.
The quality of air indoors is a problem also in many developed countries because buildings were 
built to be airtight and energy efficient. Chemicals produced by heating and cooling systems, 
smoking and evaporation from buildings materials accumulate indoors and create a pollution 
problem.
The health effects of ambient air pollution have been difficult to document with certainty until 
recent years. This is because of methodological problems in assessing exposure, other factors 
that cause respiratory disease (such as cigarette smoking, respiratory tract infections, and 
allergies), and the difficulty of studying such effects in large populations.
Recently, however, a series of highly sophisticated and convincing studies from virtually every 
continent have demonstrated that air pollution has a major effect on human health. Respiratory 
symptoms are the most common adverse health effects from air pollution of all types. Following 
Table presents a summary of major health effects thought to be caused by community air 
pollution. Respiratory effects of air pollution, particularly complicating chronic bronchitis, may 
place an additional strain on the heart as well.
Disease or How air pollution
condition may affect it Associated factors
Eye irritation Specific effect o f photochemical 
oxidants, Possibly aldehydes or 
peroxyacetyl Nitrates; particulate
Susceptibility differs
matter (fly ash} as a Foreign body
Acute bronchitis Direct irrigative effects o f SOs. Cigarette smoking may
soot and Petrochemical pollution have a more ihan 
Additive interaction
Chronic bronchitis Aggravation (increase in Cigarette smoking.
Frequency or Severity) o f cough 
or sputum Associated with a ny 
sort o f pollution
occupation
Asthma Aggravation from respiratory usually pre-existing
irritation, Possibly on respiratory allergy
reflex basis or airway hyperactivity
Headache Carbon m onoxide sufficient Smoking m ay also increase
To lead to more than 10% carboxyhaemoglobin but not
carboxy haemoglobin Enough to lead to headache
Lead toxicity Add to body burden C lose proxim ity to lead
source; Exposure at home
Air pollution is associated with increased risk of death from heart disease and lung disease, 
even at levels below those known to be acutely toxic to the heart. Mucosal irritation in the form 
of acute or chronic bronchitis, nasal tickle, or conjunctivitis is characteristic of high levels of air 
pollution, although individuals vary considerably in their susceptibility to such effects.
The eye irritation is particularly severe, in the setting of high levels of particulates (which need to 
be in the respirable range described and may be quite large soot particles) or of high 
concentrations of photochemical oxidants and especially aldehydes.
There is little evidence to suggest that community air pollution is a significant cause of cancer 
except in unusual and extreme cases. However, emissions from particular sources may be 
cancer-causing. Examples of cancer associated with community air pollution may include point- 
source emissions from some smelters with poor controls that release arsenic, which can cause 
lung cancer. Central nervous system effects, and possibly learning disabilities in children, may 
result from accumulated body burdens of lead, where air pollution contributes a large fraction of 
exposure because of lead additives in gasoline.
These health effects are better characterized for populations than for individual patients. 
Establishing a relationship between the symptoms of a particular patient and exposure to air 
pollution is more difficult than interpreting the likely health effects on an entire community. It is 
important to understand that these pollutants are seasonal in their pattern. Both ozone and 
sulfates, together with ultra fine particulates, tend to occur together during the summer months 
in most developed areas. Ozone, oxides of nitrogen, aldehydes, and carbon monoxide tend to
occur together in association with traffic, especially in sunny regions. Some pollutants, such as 
radon, are only hazards indoors or in a confined area. Others are present both indoors and 
outdoors, with varying relative concentrations.
Classifications of Air Pollutants
Air pollutants can be classified as
a. Criteria Pollutants
There are 6 principal, or "criteria” pollutants regulated by the US-EPA and most countries in the 
world:
• Total suspended particulate matter (TSP), with additional subcategories of particles smaller 
then 10 pm in diameter (PM10), and particles smaller than 2.5 pm in diameter (PM2.5). PM can 
exist in solid or liquid form, and includes smoke, dust, aerosols, metallic oxides, and pollen. 
Sources of PM include combustion, factories, construction, demolition, agricultural activities, 
motor vehicles, and wood burning. Inhalation of enough PM over time increases the risk of 
chronic respiratory disease.
• Sulfur dioxide (SO2). This compound is colorless, but has a suffocating, pungent odor. The 
primary source of SO2 is the combustion of sulfur-containing fuels (e.g., oil and coal). Exposure 
to SO2 can cause the irritation of lung tissues and can damage health and materials.
• Nitrogen oxides (NO and NO2). NO2 is a reddish-brown gas with a sharp odor. The primary 
source of this gas is vehicle traffic, and it plays a role in the formation of tropospheric ozone. 
Large concentrations can reduce visibility and increase the risk of acute and chronic respiratory 
disease.
• Carbon monoxide (CO). This odorless, colorless gas is formed from the incomplete 
combustion of fuels. Thus, the largest source of CO today is motor vehicles. Inhalation of CO 
reduces the amount of oxygen in the bloodstream, and high concentrations can lead to 
headaches, dizziness, unconsciousness, and death.
• Ozone (O3). Tropospheric ("low-level”) ozone is a secondary pollutant formed when sunlight 
causes photochemical reactions involving NOX and VOCs. Automobiles are the largest source 
of VOCs necessary for these reactions. Ozone concentrations tend to peak in the afternoon, 
and can cause eye irritation, aggravation of respiratory diseases, and damage to plants and 
animals.
• Lead (Pb). The largest source of Pb in the atmosphere has been from leaded gasoline 
combustion, but with the gradual elimination worldwide of lead in gasoline, air Pb levels have 
decreased considerably. Other airborne sources include combustion of solid waste, coal, and 
oils, emissions from iron and steel production and lead smelters, and tobacco smoke. Exposure 
to Pb can affect the blood, kidneys, and nervous, immune, cardiovascular, and reproductive 
systems.
Page 5


Module-IV
A ir pollution
Unit of measurement
Concentrations of air pollutants are commonly expressed asthe mass of pollutant per Unit 
volume of air mixture, as mg/m3 , pg/m3, ng /m3
Concentration of gaseous pollutants may also be expressed as volume of pollutant per million 
volumes of the air plus pollutant mixture (ppm) where 1ppm= 0.0001 % by volume. It is 
sometimes necessary to convert from volumetric units to mass per unit volume and vice versa.
The relation ship between ppm and mg/m3 depends on the gas density, which in turn depends 
on:™Temperature, Pressure, Molecular weight of the pollutant
The following expression can be uses to convert of between ppm and mg/m3 at any temperature 
or pressure.
mg/m3 = 273 X PPM X molecular w t X pressure 
22.4 X temperature
Simply multiply the calculated value of mg/m3 by 1000 to obtain pg/m3 . The constant 22.4 is the 
volume in liter occupied by 1 mole of an ideal gas at standard concentration (0°c and 1 atm.). 
One 14 mole of any substance is a quantity of that substance whose mass in grams numerically 
equals its molecular weight
Sources and Classification of pollutants
Air pollution may be defined as any atmospheric condition in which certain substances are 
present in such concentrations that they can produce undesirable effects on man and his 
environment. These substances include gases (SOx, NOx, CO, HCs, etc) particulate matter 
(smoke, dust, fumes, aerosols) radioactive materials and many others. Most of these 
substances are naturally present in the atmosphere in low (background) concentrations and are 
usually considered to be harmless. A particular substance can be considered as an air pollutant 
only when its concentration is relatively high compared with the back ground value and causes 
adverse effects.
Air pollution is a problem of obvious importance in most of the world that affects human, plant 
and animal health. For example, there is good evidence that the health of 900 million urban 
people suffers daily because of high levels of ambient air sulfur dioxide concentrations. Air 
pollution is one of the 6 most serious environmental problems in societies at all level of
economic development. Air pollution can also affect the properties of materials (such as rubber), 
visibility, and the quality of life in general. Industrial development has been associated with 
emission to air of large quantities of gaseous and particulate emissions from both industrial 
production and from burning fossil fuels for energy and transportation.
When technology was introduced to control air pollution by reducing emissions of particles, it 
was found that the gaseous emissions continued and caused problems of their own. Currently 
efforts to control both particulate and gaseous emissions have been partially successful in much 
of the developed world, but there is recent evidence that air pollution is a health risk even under 
these relatively favorable conditions.
In societies that are rapidly developing sufficient resources may not be invested in air pollution 
control because of other economic and social priorities. The rapid expansion of the industry in 
these countries has occurred at the same time as increasing traffic from automobiles and trucks, 
increasing demands for power for the home, and concentration of the population in large urban 
areas called mega cities. The result has been some of the worst air pollution problem in the 
world.
In many traditional societies, and societies where crude household energy sources are widely 
available, air pollution is a serious problem because of inefficient and smoky fuels used to heat 
buildings and cook. This causes air pollution both out door and indoors. The result can be lung 
disease, eye problems, and increased risk of cancer.
The quality of air indoors is a problem also in many developed countries because buildings were 
built to be airtight and energy efficient. Chemicals produced by heating and cooling systems, 
smoking and evaporation from buildings materials accumulate indoors and create a pollution 
problem.
The health effects of ambient air pollution have been difficult to document with certainty until 
recent years. This is because of methodological problems in assessing exposure, other factors 
that cause respiratory disease (such as cigarette smoking, respiratory tract infections, and 
allergies), and the difficulty of studying such effects in large populations.
Recently, however, a series of highly sophisticated and convincing studies from virtually every 
continent have demonstrated that air pollution has a major effect on human health. Respiratory 
symptoms are the most common adverse health effects from air pollution of all types. Following 
Table presents a summary of major health effects thought to be caused by community air 
pollution. Respiratory effects of air pollution, particularly complicating chronic bronchitis, may 
place an additional strain on the heart as well.
Disease or How air pollution
condition may affect it Associated factors
Eye irritation Specific effect o f photochemical 
oxidants, Possibly aldehydes or 
peroxyacetyl Nitrates; particulate
Susceptibility differs
matter (fly ash} as a Foreign body
Acute bronchitis Direct irrigative effects o f SOs. Cigarette smoking may
soot and Petrochemical pollution have a more ihan 
Additive interaction
Chronic bronchitis Aggravation (increase in Cigarette smoking.
Frequency or Severity) o f cough 
or sputum Associated with a ny 
sort o f pollution
occupation
Asthma Aggravation from respiratory usually pre-existing
irritation, Possibly on respiratory allergy
reflex basis or airway hyperactivity
Headache Carbon m onoxide sufficient Smoking m ay also increase
To lead to more than 10% carboxyhaemoglobin but not
carboxy haemoglobin Enough to lead to headache
Lead toxicity Add to body burden C lose proxim ity to lead
source; Exposure at home
Air pollution is associated with increased risk of death from heart disease and lung disease, 
even at levels below those known to be acutely toxic to the heart. Mucosal irritation in the form 
of acute or chronic bronchitis, nasal tickle, or conjunctivitis is characteristic of high levels of air 
pollution, although individuals vary considerably in their susceptibility to such effects.
The eye irritation is particularly severe, in the setting of high levels of particulates (which need to 
be in the respirable range described and may be quite large soot particles) or of high 
concentrations of photochemical oxidants and especially aldehydes.
There is little evidence to suggest that community air pollution is a significant cause of cancer 
except in unusual and extreme cases. However, emissions from particular sources may be 
cancer-causing. Examples of cancer associated with community air pollution may include point- 
source emissions from some smelters with poor controls that release arsenic, which can cause 
lung cancer. Central nervous system effects, and possibly learning disabilities in children, may 
result from accumulated body burdens of lead, where air pollution contributes a large fraction of 
exposure because of lead additives in gasoline.
These health effects are better characterized for populations than for individual patients. 
Establishing a relationship between the symptoms of a particular patient and exposure to air 
pollution is more difficult than interpreting the likely health effects on an entire community. It is 
important to understand that these pollutants are seasonal in their pattern. Both ozone and 
sulfates, together with ultra fine particulates, tend to occur together during the summer months 
in most developed areas. Ozone, oxides of nitrogen, aldehydes, and carbon monoxide tend to
occur together in association with traffic, especially in sunny regions. Some pollutants, such as 
radon, are only hazards indoors or in a confined area. Others are present both indoors and 
outdoors, with varying relative concentrations.
Classifications of Air Pollutants
Air pollutants can be classified as
a. Criteria Pollutants
There are 6 principal, or "criteria” pollutants regulated by the US-EPA and most countries in the 
world:
• Total suspended particulate matter (TSP), with additional subcategories of particles smaller 
then 10 pm in diameter (PM10), and particles smaller than 2.5 pm in diameter (PM2.5). PM can 
exist in solid or liquid form, and includes smoke, dust, aerosols, metallic oxides, and pollen. 
Sources of PM include combustion, factories, construction, demolition, agricultural activities, 
motor vehicles, and wood burning. Inhalation of enough PM over time increases the risk of 
chronic respiratory disease.
• Sulfur dioxide (SO2). This compound is colorless, but has a suffocating, pungent odor. The 
primary source of SO2 is the combustion of sulfur-containing fuels (e.g., oil and coal). Exposure 
to SO2 can cause the irritation of lung tissues and can damage health and materials.
• Nitrogen oxides (NO and NO2). NO2 is a reddish-brown gas with a sharp odor. The primary 
source of this gas is vehicle traffic, and it plays a role in the formation of tropospheric ozone. 
Large concentrations can reduce visibility and increase the risk of acute and chronic respiratory 
disease.
• Carbon monoxide (CO). This odorless, colorless gas is formed from the incomplete 
combustion of fuels. Thus, the largest source of CO today is motor vehicles. Inhalation of CO 
reduces the amount of oxygen in the bloodstream, and high concentrations can lead to 
headaches, dizziness, unconsciousness, and death.
• Ozone (O3). Tropospheric ("low-level”) ozone is a secondary pollutant formed when sunlight 
causes photochemical reactions involving NOX and VOCs. Automobiles are the largest source 
of VOCs necessary for these reactions. Ozone concentrations tend to peak in the afternoon, 
and can cause eye irritation, aggravation of respiratory diseases, and damage to plants and 
animals.
• Lead (Pb). The largest source of Pb in the atmosphere has been from leaded gasoline 
combustion, but with the gradual elimination worldwide of lead in gasoline, air Pb levels have 
decreased considerably. Other airborne sources include combustion of solid waste, coal, and 
oils, emissions from iron and steel production and lead smelters, and tobacco smoke. Exposure 
to Pb can affect the blood, kidneys, and nervous, immune, cardiovascular, and reproductive 
systems.
b. Toxic Pollutants
Hazardous air pollutants (HAPS), also called toxic air pollutants or air toxics, are those 
pollutants that cause or may cause cancer or other serious health effects, such as reproductive 
effects or birth defects. The US-EPA is required to control 188 hazardous air pollutants
Examples of toxic air pollutants include benzene, which is found in gasoline; perchlorethlyene, 
which is emitted from some dry cleaning facilities; and methylene chloride, which is used as a 
solvent and paint stripper by a number of industries.
c. Radioactive Pollutants
Radioactivity is an air pollutant that is both geogenic and anthropogenic. Geogenic radioactivity 
results from the presence of radionuclides, which originate either from radioactive minerals in 
the earth’s crust or from the interaction of cosmic radiation with atmospheric gases. 
Anthropogenic radioactive emissions originate from nuclear reactors, the atomic energy industry 
(mining and processing of reactor fuel), nuclear weapon explosions, and plants that reprocess 
spent reactor fuel. Since coal contains small quantities of uranium and thorium, these 
radioactive elements can be emitted into the atmosphere from coal-fired power plants and other 
sources.
d. Indoor Pollutants
When a building is not properly ventilated, pollutants can accumulate and reach concentrations 
greater than those typically found outside. This problem has received media attention as "Sick 
Building Syndrome”. Environmental tobacco smoke (ETS) is one of the main contributors to 
indoor pollution, as are CO, NO, and SO2, which can be emitted from furnaces and stoves. 
Cleaning or remodeling a house is an activity that can contribute to elevated concentrations of 
harmful chemicals such as VOCs emitted from household cleaners, paint, and varnishes. Also, 
when bacteria die, they release endotoxins into the air, which can cause adverse health 
effects31. So ventilation is important when cooking, cleaning, and disinfecting in a building. A 
geogenic source of indoor air pollution is radon32.
Other classifications
Air pollutants come in the form of gases and finely divided solid and liquid aerosols. 
Aerosols are loosely defined as "any solid or liquid particles suspended in the air” (1).
Air pollutants can also be of primary or secondary nature. Primary air pollutants are the ones 
that are emitted directly into the atmosphere by the sources (such as power-generating plants).
Secondary air pollutants are the ones that are formed as a result of reactions between primary 
pollutants and other elements in the atmosphere, such as ozone.
Types of pollutants
Sulfur Dioxide