1
CHAPTER#1
AIR QUALITY: DEFINITIONS
CHARACTERISTICS&
PERSPECTIVES
2
What is Atmosphere?
An atmosphere is a layer of gas or layers of gases that envelope a planet, and is held in
place by the gravity of the planetary body.
The atmosphere of Earth is composed of nitrogen (78%), oxygen (21%), argon (0.9%),
carbon dioxide (0.04%) and trace gases.
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Biosphere is the zone of life on Earth
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CLASSIFICATION OF ATMOSPHERE IN
LAYERS
5
PRESSURE VARIANCE
6
TEMPERATURE VARIATION
• WHEN THE ALTITUDE INCREASES, THE
TEMPERATURE DECREASES
• JABAL AKTAR IS COOLER THAN
BIRKAT ALMOUZ
• HIMALAYAS [8824 M ] IS MUCH
COOLER THAN ANY OTHER
PLACE IN THE WORLD
[ TEMPERATURE IS -60
DEGREE CELSIUS]
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COMPOSITION OF CLEAN AIR
8
DEFINITION OF AIR POLLUTION
9
REASONS FOR AIR POLLUTION
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IDENTIFYING AIR POLLUTION
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Natural Fog
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Pollen Grains
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Examples
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An Illinois coal is burned at a rate of 1.00 kg per
second. If the analysis of the coal reveals a sulfur
content of 3.00 %, what is the annual rate of
emission of SO2?
Sulfur dioxide
(SO2)
Sulfur in
Sulfur dioxide
(ash)
MASS BALANCE:
Sin = Sash + SSO2
Sin = 1 kg/s x 0.030 = 0.030 kg/s
Sin = 9.46 x 105 kg/yr
Sash = (0.05)(9.46 x 105 kg/yr) = 4.73 x 104 kg/yr
SSO2 = Sin – Sash = 9.46 x 105 – 4.73 x 104
SSO2 = 8.99 x 105 kg/yr
SSO2 = 8.99 x 105 kg/yr (64 SO2/32 S)
SSO2 = 1.80 x 106 kg/yr
Determine whether or not a pulverized coal, dry
bottom, wall-fired boiler using bituminous coal at
power plant rate at 61 MW meets the NSPS for
SO2.The power plant burns bituminous coal with a
sulfur content of 1.8% and ash content of 6.2 %.
The coal has a heating value of 14,000 Btu/lb. the
boiler efficiency is 35%. Use the emission factors to
estimate the emissions. Assume the efficiency of
SO2 control is 85% .
Coal firing rate = 61 MW / 0.35 = 174.3 x 106 W
Mass of coal burned
= 174.3 x 106 J/s (3600 s) (1 Btu/1054.4 J)
= 5.95 x 108 Btu/hr
Using the EPA emission factor of 38S for
bituminous coal:
Uncontrolled SO2 emission rate = 38 (1.8)
= 68.4 lbm
ton coal
Check emission rate:
Estimated SO2 emission rate
= 68.4 lb/ton coal(5.95 x 108 Btu)(1 ton/2000lb)(0.15)
14,000 Btu/lb
= 218.05 lbm
SO2 emission rate (per million Btu)
= 218.05 lb/(5.95 x 108 Btu)(106)
= 0.37 lb/million Btu
Comment:
meets the standard 1.2 lb/million Btu but not the
90% reduction requirement
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AIR POLLUTION EPISODES
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EPISODES
• EPISODE – used as a refined form of the
word disaster/ incident.
• Indeed it was the shock of these disasters that
stimulated the first modern legislative action
to control of air pollutants.
• Careful study of different known episodes
reveal that all of the incidents had something
in common.
AIR POLLUTION EPISODES
• CRUCIAL INGREDIENTS FOR AN EPISODE TO
HAPPEN:
– Large number of population sources
– A restricted air volume
– Failure of officials to recognize that
anything is wrong
– The presence of water droplets of the right
size
Source: Goldsmith 1968
AIR POLLUTION EPISODES
Major air pollution episodes(WHO, 1961)
Donora, 1948
London, 1952
Population
Weather
12,300
8,000,000
Anticyclone
Anticyclone
inversion and fog inversion and fog
Topography
Most probable
source of pollutants
River valley
Industry
steel and zinc
plants
River plain
Household and
coal burning
Major air pollution episodes (WHO, 1961)
Donora, 1948
Nature of illnesses Chemical irritation of
exposed membranous
surfaces
# of deaths
Time of death
Suspected cause of
irritation
17
London, 1952
Chemical irritation of
exposed
membranous surfaces
4000
Began after second day
of episode
Began after second
day of episode
Sulfur oxides with
particulates
Sulfur oxides with
particulates
Location
of
Bhopal
in
India
BACKGROUND INFORMATION
The Bhopal disaster, also referred to as
the Bhopal gas tragedy, was a gas leak
incident in India, considered to be the
world's worst industrial disaster.
Monday, December 3rd, 1984. (28 years ago)
BACKGROUND INFORMATION
• One of Union Carbide’s Pesticide factories was
located in Bhopal, India.
• Union Carbide of India Limited (UCIL) was a
subsidiary of The Union Carbide Corporation
(UCC).
• The Factory produced carbanate pesticides. One
Component was Methyl Isocyanate (MIC).
• A rapidly growing community of roughly 900,000
people.
The system that failed
The Bhopal Disaster!
• 40 tons of deadly gases suddenly burst out into the
atmosphere.
• Workers fled in panic.
• People woke up coughing violently and with eyes
burning as if chilli powder had been flung into them.
• Neighbouring communities fled in panic
• The streets were foul with vomit. Those who fell were
trampled by the crowd.
• The worst affected were the children: unable to walk
and breathe, they simply suffocated and died.
The Bhopal Disaster!
• Local hospitals were soon overwhelmed with
the injured
• Over 500,000 people were exposed to methyl
isocyanate gas and other chemicals.
Contributing Factors
Factors leading to the magnitude of the gas leak
mainly included problems such as:
• storing MIC in large tanks and filling beyond
recommended levels, poor maintenance after the
plant ceased MIC production at the end of 1984,
• safety systems being switched off to save
money— including the MIC tank refrigeration
system which could have mitigated the disaster
severity.
• shortcomings in health care and socio-economic
rehabilitation.
Contributing Factors
• use of a more dangerous pesticide manufacturing
method,
• plant location close to a densely populated area,
• undersized safety devices,
• Plant management deficiencies were also
identified – lack of skilled operators, reduction of
safety management, insufficient maintenance,
and inadequate emergency action plans.
AFTERMATH OF IT ALL
• The official immediate death toll was 2,259.
The government of Madhya Pradesh confirmed a
total of 3,787 deaths related to the gas
release. Others estimate 8,000 died within two
weeks and another 8,000 or more have since died
from gas-related diseases. A government affidavit
in 2006 stated the leak caused 558,125 injuries
including 38,478 temporary partial injuries and
approximately 3,900 severely and permanently
disabling injuries.
Victims Remain Victims
• >Resident Leela was one of those caught by Union
Carbide’s cloud of poison gas.
• >Her family of six survived, but ever since they
have suffered from breathlessness and spells of
vomiting. One of her sons has gone blind. All six
family members suffer from breathlessness and
spells of vomiting.
• >Burdened by injury they cannot earn well. The
family’s joint income is $30 a month.
• For the gas victims of Bhopal every day of the past
28 years has been a struggle against
breathlessness, nausea, brain damage, cancers,
fevers, numbness, panic attacks, menstrual chaos,
monstrous births.
Economic Effects
•
•
•
•
•
•
loss of jobs (650 permanent jobs were lost)
loss of earning capacity of victims
business disruptions
cost of compensation
rehabilitation, and legal costs.
"Investment hasn't been coming to Bhopal
because of the stigma."
NOW
* Still in a state Recovering
* Almost 30 years later, one out of four babies
born in Bhopal is born dead.
* Countless people suffer from breathing
difficulties, cancer, nerve diseases and
infertility.
* The ground water is still contaminated.
NOW
Deteriorating
portion of the
MIC plant,
decades after the
gas leak.
Contributor to
ongoing
contamination.
NOW
Bhopal
child born
with birth
defects
GLOBAL EFFECTS OF AIR POLLUTION
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GLOBAL WARMING
What is global warming?
Since the Industrial Revolution, the global annual temperature has increased in total by a little
more than 1 degree Celsius, or about 2 degrees Fahrenheit. Between 1880—the year that
accurate recordkeeping began—and 1980, it rose on average by 0.07 degrees Celsius (0.13
degrees Fahrenheit) every 10 years. Since 1981, however, the rate of increase has more than
doubled: For the last 40 years, we’ve seen the global annual temperature rise by 0.18 degrees
Celsius, or 0.32 degrees Fahrenheit, per decade.
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What causes global warming?
A: Global warming occurs when carbon dioxide (CO2) and other air pollutants collect in the
atmosphere and absorb sunlight and solar radiation that have bounced off the earth’s surface.
Normally this radiation would escape into space, but these pollutants, which can last for years to
centuries in the atmosphere, trap the heat and cause the planet to get hotter. These heat-trapping
pollutants—specifically carbon dioxide, methane, nitrous oxide, water vapor, and synthetic
fluorinated gases—are known as greenhouse gases, and their impact is called the greenhouse
effect.
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Earth’s Atmospheric Gases
Nitrogen (N2)
Oxygen (O2)
NonGreenhouse
Gases
99%
Water (H2O)
Carbon Dioxide (CO2)
Methane (CH4)
Greenhouse
Gases
1%
The image below describes the Greenhouse effect and the role
of greenhouse gases
Sun
Greenhouse Effect
The image shows the
concentration of CO2 in the
atmosphere over a period of
time if emissions continue
unaltered.
CO2 concentration
after 50 years of
unrestricted fossil
fuel burning (600
ppmv)
Present CO2
concentration
(386 ppmv)
270
240
210
180
Temp.
Proxy
CO2 (ppmv)
300
800
600
400
200
Thousands of Years Before Present
0
Households are Big Contributors to Climate Change
Of all U.S. greenhouse gas
emissions come from
households:
• Vehicles
• Home Heating
• Electricity
So how can each of us slow
global warming now?
Reduce our consumption of fossil fuels
Because greenhouse gas emissions are tied very closely to our
energy consumption, using less fossil fuel based energy puts fewer
greenhouse gases into the atmosphere.
This will help slow global warming.
Mountaintop removal for
coal mining near Rawl,
West Virginia.
50% of electricity in the
United States is produced
from coal.
(
Average Electricity Emission
Factors
Region/State
South Atlantic
North Carolina
Virginia
West Virginia
CO2 lb/kWh CO2 tons/MWh CO2 Metric tons/MWh CH4 lbs/MWh NO2 lbs/MWh
1.35 0.674
0.612
0.0127 0.0207
1.24 0.621
0.563
0.0105 0.0203
1.16 0.582
0.528
0.0137 0.0192
1.98 0.998
0.897
0.0137 0.0316
Kitchen Light Fixture
Three 60 Watt Bulbs
How much energy are those bulbs using?
1
Wattage
of the bulbs
(Incandescent
bulbs)
60 W
2
# of
bulbs
Watts
Used
(Wattage
x number
of bulbs)
4
Hours used
per day
(60 x 3)
3
bulbs
(CFL bulbs)
18 W
3
3
bulbs
180 W
10 hours a
day
18 x3
10 hours a
day
54 W
5
Watts Used
(#3) x Total
Hours/day
(#4)
6
Watts
hours /
year
7
Kilowatt
hours /
year
(#5 x 365
days)
(1000Wh =
1kWh)
(divide #6
by 1000)
(180 x 10)
(1800 x 365)
(640,800/10
00)
1800
Wh/day
640,800
Wh/ year
640.8
kWh per
year
54 x 10
540x365
540
Wh/day
197,100
Wh/day
197,100
1000
197.1
kWh/yr
3 BULB REPLACEMENT EMISSION and COST COMPARISON
INCANDESCENT vs. COMPACT FLUORESCENT
Incandescents
Total kWh for 3 bulb (#7 from
above)
640.8 kWh
Cost (kWh #7 x $.18)
$115.34
CO2 produced @ 1.16 lbs/kWh
743.3
Compact Fluorescents
(CFLs)
197 kWh
lbs
CO2 not emitted by switching 3 bulbs
$35.46
228.52 lbs
514.8
(C O2 of incandescents - C O2 of CFLs)
Money saved in energy
(Cost incandescents - cost of CFLs)
$79.88
lbs
We can make some simple substitutions
Replacing just 1 incandescent light bulb with 1 compact
florescent bulb saves about 150 pounds of carbon
dioxide per year!
If every American household replaced just 5 high-use
incandescent bulbs with compact florescent lights we'd
collectively save more than $8 billion each year in energy costs
and we would prevent the greenhouse gases equivalent to the
emissions from nearly 10 million cars.
Source: http://www.energystar.gov
Be Bulb Smart—Use CFLs
Incandescent
What’s the
difference?
Compact
Fluorescent
500 lbs.
of coal
•1,430 lbs. CO2 pollution avoided
•$30 saved
Small changes really add up
Replace your old refrigerator
with a new Energy Star:
Annual savings:
$90; 700 pounds CO2
Set your thermostat down a few
degrees in the winter
Annual savings:
$135; 1400 pounds CO2
Drive JUST 10 fewer miles per week
Annual savings:
$80; 520 pounds CO2
Wash clothes in cold water only
Annual savings:
$70; 500 pounds CO2
Reduce your garbage by 10%
through greater recycling or reduced
packaging
Annual savings:
1200 pounds CO2
Caulk and weather-strip around doors and
windows
Annual savings:
$80; 650 pounds CO2
*
These are mid-range estimates from
published sources; your savings may vary.
How is global warming linked to extreme weather?
A: Scientists agree that the earth’s rising temperatures are fueling longer and hotter heat
waves, more frequent droughts, heavier rainfall, and more powerful hurricanes.
What are the other effects of global warming?
• Melting Of Polar Ice
Caps
 Rise in Sea Levels
 Throw global
ecosystems out of
balance
 Will endanger several
species of animals
•
Other fallouts include
 Spread of disease
 Warmer waters and more hurricanes
 Increased probability and intensity of droughts
and heat waves
 Economic consequences
 Loss of Biodiversity
 Destruction of Ecosystems
• Mitigation of global
warming involves taking
actions to reduce
greenhouse gas
emissions.
Energy efficiency and
conservation
 Urban Planning
 Building Design
 Use of passive solar building
design, low-energy building,
or zero-energy building
techniques, using renewable
heat sources
 Transport
 plug-in hybrid electric
vehicles
 A shift from air transport and
truck transport to electric rail
transport
 Increased use of biofuels
Carbon Capture And Storage
(CCS)
• Carbon capture and
storage (CCS) is a plan
to mitigate climate
change by capturing
carbon dioxide (CO2)
from large point sources
such as power plants
and subsequently
storing it away safely
instead of releasing it
into the atmosphere.
Carbon Sequestration
– Carbon
sequestration is a
term that describes
processes that
remove carbon
from the
atmosphere.
• Seeding oceans
with iron
• Solar shades
• Geoengineering
Seeding Oceans With Iron
• It is motivated by
evidence that
seeding the oceans
with iron will
increase
phytoplankton
populations, and
thereby draw more
carbon dioxide from
the atmosphere.
Solar Shades
• Some
scientists
have
suggested using aerosols
and/or sulfate dust to alter
the Earth's reflectivity by
burning sulfur in the
stratosphere,
as
an
emergency measure to
increase global dimming
and thus stave off the
effects of global warming.
• It
would,
however,
increase the environmental
problem of acid rain and
drought.
Governmental And
Intergovernmental Action
• Policies like:
– Kyoto Protocol
– Carbon emissions
trading
– Carbon tax
Population Control
• The population explosion is a
fundamental factor that has led
to global warming
• Because of this, various
organizations promote
population control as a means
for mitigating global warming.
Proposed measures include
improving access to family
planning and reproductive
health care and information,
public education about the
consequences of continued
population growth.
Ozone (O3) is a dangerous street level pollutant, contributing to photochemical smog. It
is also a minor greenhouse gas, contributing to climate change.
The main reason people are aware of its existence is through its beneficial effects in the
stratospheric ‘ozone layer’ 5 to 30 miles up, which provides an important protection for
life on Earth from the dangerous effects of the sun’s radiation, by absorbing biologically
damaging ultraviolet sunlight (UV-B).
The hole in the ozone layer was first noticed over the British Antarctic Survey station
Halley, Antarctica10.
Today, up to 60% of the total overhead amount of ozone is depleted during the Antarctic
spring. In the Arctic Polar Regions a similar but smaller hole has appeared in 6 out of the
last 9 years.
Increases in surface UV-B radiation have been observed in association with local
decreases in stratospheric ozone, from both ground-based and satellite-borne
instruments.
A dobson unit is the most basic measure used in ozone research.One Dobson Unit (DU)
is defined to be 0.01 mm thickness at STP (standard temperature and pressure). Ozone
layer thickness is expressed in terms of Dobson units, which measure what its physical
thickness would be if compressed in the Earth's atmosphere.
Ozone-depleting compounds are a group of chemicals called halocarbons that can
contain the elements chlorine, fluorine, bromine, carbon, and hydrogen.
As early as 1974 an article in Nature11 had shown that compounds being added to the
Earth’s atmosphere were destroying the ozone layer.
One group of halocarbons called chlorofluorocarbons (CFCs) invented in 1928 found
use in aerosols, foams, refrigeration, air conditioners, cleaning of electronic components,
and as a solvent. Another group (halons) was used in fire extinguishers.
Once released, halocarbons are long-lived and stable chemicals that rise up and persist
in the stratosphere for many years, where they break down ozone.
Policy response on Ozone depletion
The UN started to address the problem in the 1970s, resulting in the 1987
Montreal Protocol on Substances that Deplete the Ozone Layer.
The Protocol aims to reduce and eventually eliminate the emissions of man-made ozone
depleting substances, by stopping their production and use, and has been modified or
strengthened five times so far by amendments.
As more ‘culprit’ depleting substances are identified, the scope of the Protocol has been
expanded.
The UN Secretary General said in September 2000 that without the Protocol,
the levels of ozone-damaging substances would have been five times higher
than they are today, but developing countries are yet to phase out CFC
emissions to meet the 2010 deadline imposed by the Montreal Protocol.
There are also reports of a black market in CFCs. According to a recent UNEP news
release, scientists predict that the ozone layer will fully recover some time in the 21st
century – ‘but only if the Protocol continues to be vigorously enforced’.
Acid Rain
Introduction to acid rain
Normal rain water is always slightly acidic because CO2
present in atmosphere. get dissolved in it form carbonic
acid. Normal acidity of rain water is 5.6
H2O (l) + CO2 (g)
H2CO3 (aq)
Because of SO2 & NO2 gases as pollutants in atmosphere.
The pH of rain is further lowered to as 2.4 & this type of
Precipitation is called as ACID RAIN.
Acid rain is combination of H2SO4, HNO3 and HCl is third
History
 Since industrial revolution, emissions of SO2 &
NO2 in atmosphere have increased.
 In 1852 ROBERT ANGUS SMITH was first to
show relation b/w acid rain & atmosphere
pollution in Manchester (England)
 Term acid rain was generated by SMITH in 1972.
 Problem of acid rain has not only increased with
population & industrial growth but has become
widespread.
Acid Rain Formation
Emissions of sulfur dioxide and nitrogen oxides react
with water vapor in the atmosphere to create sulfuric
and nitric acids.
Causes Of Acid Rain
 NATURAL CAUSES:Volcanic emissions.
 Biological processes.
Lightning.
 ANTHROPOGENIC CAUSES:Factories (industrialization)
Motor vehicles, automobile exhaust.
Coal based power plants.
Domestic fires.
Smelters.
Measurement of acid rain
Acid rain is measured through pH tests that determine the
concentration of hydrogen ions in a liter of fluid. The pH
(potential for hydrogen) scale is used to measure acidity or
alkalinity. It runs from 0 to 14. (The greater the concentration of
hydrogen ions and the lower the pH number, the more acidic a
substance is; the lower the concentration of hydrogen ions and the
higher the pH number, the more alkaline—or basic—a substance
is.) So a pH greater than 7 indicates an alkaline substance while a
pH less than 7 indicates an acidic substance
Chemical Processes Involved In
acid rain
Formation Of Sulphuric Acid
S + O2
SO2 + 1/2O2 + H2O
SO2
H2SO4
Reaction Involving Formation Of Nitric Acid
NO + O3
NO2 + O3
NO3 + NO2
N2O5 + H2O
NO2+O2
NO3+O2
N2O5
2HNO3
Adverse Effect Of Acid Rain
Plants

Effects
plants
and
trees.

Causes
yellowing
leaf tissue (chlorosis).
of
 Direct effect on plant growth
due to toxification of soil
 It takes away soil nutrients
causing stunted growth.
 Block stomatal pores of leaves.
 Electron transport system,
biochemical
reactions
dominated by pH are effected.
 Degradation
chlorophyll.
of
plant
b. Soil
 Acid rain damages soil
biology and chemistry
 Microbes not able to
tolerate low pH and die
 Upper fertile layer of soil
is affect as essential
nutrients are leached
away from soil
a. Surface Water And
Aquatic Animals
 Acid rain causes lower pH &
high aluminum
conc. in
surface water that causes
damages to fish and aquatic
animals.
 Biodiversity of water body is
reduced.
 Lakes, rivers are fragile
ecosystems
where
each
species depend on other to
survive ,if one disappears
other too disappears.
c. Human Health
Aerosol mist of sulfuric acid has
very serious respiratory effects.
Acidification play havoc with
human nervous system ,respiratory
system and digestive system.
e. Effect On Buildings
 Causes
extensive
damage
to
buildings, structural materials of
marble ,limestone, slate etc.
CaCO3+H2SO4 CaSO4+H2O+CO2
 In Greece and Italy invaluable stone
statues have been partially dissolved
by acid rain.
 Taj Mahal in Agra is also suffering
due to acid fumes from Mathura
refinery.
Deterioration of Taj Mahal
 Taj, the seventh wonder of
world getting deteriorated
because of emissions of
Mathura oil refinery which
lies 40 km away from Taj
 The oil refinery emits 25-30
tones of SO2 daily in spite of
using low sulphur fuels.
Control measures
•
Clean combustion technologies
• Using pollution control equipments
• Replacement of coal by natural gas or renewable energy resources
• Liming of lakes and soils
• Formulate the policy framework for reduction of sulfur dioxide and
other acid rain causing gas emissions.
• Support a set of subproject that promote cleaner production, reduce
acid rain and air pollution, improve the environment.
“Soft” (Bituminous) Coal
This is coal that has
a low sulfur content.
Liming
The process of adding a lime or calcium hydroxide (a base)
to acidified lakes.
Use Energy Sources that Don’t Produce Nitrogen or Sulfur
Oxides
Health Effects of Air Pollution
Air Pollution
• The Clean Air Act requires EPA to set National
Ambient Air Quality Standards (NAAQS) for
six common air pollutants (also known
as “criteria air pollutants").
• These pollutants are found all over the U.S.,
some from natural sources and some from
man-made sources.
• They can harm your health and the
environment, and cause property damage.
Criteria Air Pollutants
•
•
•
•
•
•
carbon monoxide
lead
ground-level ozone
particulate matter
nitrogen dioxide
sulfur dioxide
Carbon Monoxide
• Incomplete oxidation of carbon results in the production of
carbon monoxide.
– Natural CO formation occurs from photochemical reactions
in the troposphere, volcanoes, forest fires, etc.
• Breathing air with a high concentration of CO
reduces the amount of oxygen that can be
transported in the blood stream to critical organs like
the heart and brain.
• At very high levels, which are possible indoors or in other
enclosed environments, CO can cause dizziness, confusion,
unconsciousness and death.
Lead
• As a result of EPA's regulatory efforts including
the removal of lead from motor vehicle
gasoline, levels of lead in the air decreased
by 98 percent between 1980 and 2014.
Lead
• Once taken into the body, lead distributes
throughout the body in the blood and is
accumulated in the bones.
• Depending on the level of exposure, lead
can adversely affect the nervous system,
kidney function, immune system,
reproductive and developmental systems
and the cardiovascular system.
• Lead exposure also affects the oxygen
carrying capacity of the blood.
Ozone
• Breathing ozone can trigger a variety of health
problems, particularly for children, the elderly,
and people of all ages who have lung diseases
such as asthma.
• Ground level ozone can also have harmful
effects on sensitive vegetation and
ecosystems.
Ozone
Particular Matter
EPA groups particle pollution into two categories:
• "Inhalable coarse particles," such as those found near
roadways and dusty industries, are larger than 2.5
micrometers and smaller than 10 micrometers in diameter.
• "Fine particles," such as those found in smoke and haze, are
2.5 micrometers in diameter and smaller. These particles can
be directly emitted from sources such as forest fires, or they
can form when gases emitted from power plants, industries
and automobiles react in the air.
Particulate Matter
Particulate Matter
Particulate matter contains microscopic solids or
liquid droplets that are so small that they can be
inhaled and cause serious health problems.
Nitrous Oxides
• Breathing air with a high concentration of NO2 can irritate
airways in the human respiratory system.
– Such exposures over short periods can aggravate respiratory diseases,
particularly asthma, leading to respiratory symptoms (such as
coughing, wheezing or difficulty breathing), hospital admissions and
visits to emergency rooms.
– Longer exposures to elevated concentrations of NO2 may contribute to
the development of asthma and potentially increase susceptibility to
respiratory infections. People with asthma, as well as children and the
elderly are generally at greater risk for the health effects of NO2.
– NO2 along with other NOx reacts with other chemicals in the air to
form both particulate matter and ozone. Both of these are also
harmful when inhaled due to effects on the respiratory system.
Sulfur Oxides
• The largest source of SO2 in the atmosphere is
the burning of fossil fuels by power plants and
other industrial facilities.
Smaller sources of SO2 emissions include:
– industrial processes such as extracting metal from
ore
– natural sources such as volcanoes
– and locomotives, ships and other vehicles and
heavy equipment that burn fuel with a high sulfur
content.
Sulfur Oxides
• At high concentrations, gaseous SO2 can harm trees and
plants by damaging foliage and decreasing growth and can
contribute to acid rain which can harm sensitive ecosystems.
• Short-term exposures to SO2 can harm the human respiratory
system and make breathing difficult. Children, the elderly, and
those who suffer from asthma are particularly sensitive to
effects of SO2.