5. An air pollutant can be
considered as a substance in
the air that, in high enough
concentrations, produces a
detrimental environmental
effect.
An environmental effect is
defined as a measurable or
perceivable detrimental
change resulting from contact
with an air pollutant.
Ambient air is the air to
which the general public has
access, i.e. any unconfined
portion of the atmosphere.
6. The two basic physical forms of air
pollutants are
• Particulate Matter
• Gases
Particulate Matter includes small solid and
liquid particles such as dust, smoke, sand,
pollen, mist and fly ash.
Gases include substances such as carbon
monoxide (CO), sulfur dioxide (SO2),
nitrogen oxides (NO2), and volatile organic
compounds (VOCs).
7. A primary pollutant is one
that is emitted into the
atmosphere directly from the
source of the pollutant and
retains the same chemical
form.
A secondary pollutant is one
that is formed by atmospheric
reactions of precursor or
primary emissions. Secondary
pollutants undergo a chemical
change once they reach the
atmosphere.
9. Sources of Pollutants in Ambient Air
Natural Sources (Biogenic)
• Volcanoes
• Wind Storms
• Forest Fires
• Pollen
• Natural Decomposition
• Natural Radioactivity
10. Man Made Sources (Anthropogenic)
Mobile Sources
• Automobiles
• Trains
• Aeroplanes
Stationary Sources (Non Moving Sources)
• Power Plants
• Industrial Facilities
11. Point Source
A point source refers to a source at
a fixed point
Area Source
An area source refers to a series of
small sources that together can affect
air quality in a region.
12. Criteria pollutants
• common
• detrimental to human welfare
These criteria pollutants are
• Carbon Monoxide (CO)
• Sulfur Oxides (SOx)
• Nitrogen Oxides (NOx)
• Ozone (O3)
• Lead (Pb)
• Particulate Matter (PM)
13. Criteria Pollutants
Carbon Monoxide
• colorless odorless gas
• formed when fuel is not burnt completely
Sources
• 50-60% produced by motor vehicles
• Heavy construction equipment
• max at heavy traffic congestions
• forest fires (Natural)
• Industrial processes
• Gas stoves, wood stoves, heaters, cigarettes
14. Criteria Pollutants
Sulfur Oxides (SOx)
• colorless gases
• formed by burning sulfur
• fuel, oil or gas containing sulfur is burnt
• SO2 criteria pollutant
• SO2 dissolves in water to form acids
• SO2 interacts with other gases &
particles to form sulfates (harmful)
Sources
• Power Plants running on furnace oil rich
in sulfur
• Industrial facilities
• Oil refineries
• Large ships, non road diesel equipment
15. Criteria Pollutants
Nitrogen Oxides (Nox)
• mostly colorless, odorless
• NO, NO2, N2O
• NO2 criteria pollutant
• highly reactive gases
• play an important role in the formation
of ozone
• formed when fuel is burnt at high temp.
• NO2 along with other particles forms a
brownish layer
Sources
• Motor vehicles
• Industrial activities
• Electric utilities
16. Criteria Pollutants
Ozone (O3)
• gas composed of three oxygen atoms
• colorless gas, electric discharge type odor
• secondary pollutant
• not emitted directly into the air
• at ground level, created by a chemical reac.
b/w Nox and VOCs in sunlight and heat
Good Ozone
• Stratospheric ozone protects us from
harmful ultraviolet radiations
Bad Ozone
• ground level ozone harmful to humans and
environment
17. Criteria Pollutants
Factors affecting Ozone concentration
• concentration of VOCs
• concentration of NOx
• local weather conditions
• intensity of sunlight
18. Criteria Pollutants
Particulate Matter (TSP, PM10, PM2.5)
• mixture of solid particles and liquid
droplets
• includes dust, soot, smoke and liquid
droplets
• can be primary as well as secondary
pollutant
• can remain suspended in air for long period
of time
PM10
• all particles less than or equal to 10µm in
diameter (one seventh the dia. Of human hair
PM2.5
• all particles less than or equal to 2.5µm in dia
19. Criteria Pollutants
Lead (Pb)
• metallic element
• found naturally in environment
Sources
• vehicular emissions
• industrial processes
• lead batteries
• leaded gasoline
• battery manufacturers
• metal refineries
• iron and steel producers
20. Table 1: Sources, Health and Welfare Effects for Criteria Pollutants.
Pollutant Description Sources Health Effects Welfare Effects
Carbon Monoxide (CO) Colorless, odorless gas Motor vehicle exhaust, Headaches, reduced Contribute to the
indoor sources include mental alertness, heart formation of smog.
kerosene or wood burning attack, cardiovascular
stoves. diseases, impaired fetal
development, death.
Sulfur Dioxide (SO2) Colorless gas that Coal-fired power plants, Eye irritation, wheezing, Contribute to the
dissolves in water vapor petroleum refineries, chest tightness, shortness formation of acid rain,
to form acid, and interact manufacture of sulfuric of breath, lung damage. visibility impairment,
with other gases and acid and smelting of ores plant and water damage,
particles in the air. containing sulfur. aesthetic damage.
Nitrogen Dioxide (NO2) Reddish brown, highly Motor vehicles, electric Susceptibility to Contribute to the
reactive gas. utilities, and other respiratory infections, formation of smog, acid
industrial, commercial, irritation of the lung and rain, water quality
and residential sources respiratory symptoms deterioration, global
that burn fuels. (e.g., cough, chest pain, warming, and visibility
difficulty breathing). impairment.
Ozone (O3) Gaseous pollutant when it Vehicle exhaust and Eye and throat irritation, Plant and ecosystem
is formed in the certain other fumes. coughing, respiratory damage.
troposphere. Formed from other air tract problems, asthma,
pollutants in the presence lung damage.
of sunlight.
Lead (Pb) Metallic element Metal refineries, lead Anemia, high blood Affects animals and
smelters, battery pressure, brain and plants, affects aquatic
manufacturers, iron and kidney damage, ecosystems.
steel producers. neurological disorders,
cancer, lowered IQ.
Particulate Matter (PM) Very small particles of Diesel engines, power Eye irritation, asthma, Visibility impairment,
soot, dust, or other matter, plants, industries, bronchitis, lung damage, atmospheric deposition,
including tiny droplets of windblown dust, wood cancer, heavy metal aesthetic damage.
liquids. stoves. poisoning, cardiovascular
effects.
23. Mobiles Sources
• responsible for more than half of the air
pollution
• cars are primary source
• vehicles produce 75-90% less pollution
for each mile driven than their 1970
counterpart
• no. of vehicles have increased immensely
Mobile Sources Pollutants
• 45% VOC emissions
• 50% NOx emissions
• 60% CO emissions
• 50% hazardous air pollutants in urban air
24. Air Quality Index
The Air Quality Index (AQI), also known as
the Air Pollution Index (API) or Pollutant
Standard Index (PSI) is an index for
reporting daily air quality
How does the AQI work?
Think of the AQI as a yardstick that runs
from 0 to 500. The higher the AQI value, the
greater the level of air pollution and the
greater the health concern
An AQI value of 100 generally corresponds to
the national air quality standard for the
pollutant, which is the level EPA has set to
protect public health
25. Air Quality Index Numerical
Levels of Health Concern Meaning
Value
Air quality is considered satisfactory,
Good 0-50
and air pollution poses little or no risk.
Air quality is acceptable; however, for
some pollutants there may be a
Moderate 51-100 moderate health concern for a very
small number of people who are
unusually sensitive to air pollution.
Members of sensitive groups may
Unhealthy for
101-150 experience health effects. The general
Sensitive Groups
public is not likely to be affected.
Everyone may begin to experience
health effects; members of sensitive
Unhealthy 151-200
groups may experience more serious
health effects.
Health alert: everyone may
Very Unhealthy 201-300 experience more serious health
effects.
Health warnings of emergency
Hazardous > 300 conditions. The entire population is
more likely to be affected.
26. To convert from concentration the equation
is used, where:
I = the (Air Quality) index,
C = the pollutant concentration,
Clow= the concentration breakpoint that is ≤ C,
Chigh= the concentration breakpoint that is ≥ C,
Ilow= the index breakpoint corresponding to Clow,
Ihigh= the index breakpoint corresponding to Chigh.
27. For example, suppose a monitor records a 24-hour
average fine particle (PM2.5) concentration of 12.0
micrograms per cubic meter. EPA's table of
breakpoints for PM2.5 is:
Clow Chigh Ilow Ihigh Category
0 15.4 0 50 Good
15.5 40.4 51 100 Moderate
Unhealthy for
40.5 65.4 101 150
Sensitive Groups
65.5 150.4 151 200 Unhealthy
150.5 250.4 201 300 Very Unhealthy
250.5 350.4 301 400 Hazardous
350.5 500.4 401 500 Hazardous
The equation above results in an AQI of:
corresponding to air quality in the "Good" range.
If multiple pollutants are measured at a monitoring
site, then the largest or "dominant" AQI value is
reported for the location
28. Particulate Matter Sampling
Numbering of filters
Filter drying and conditioning
Filter
(200C, 50% R.H), 24 hrs
Preparation
Weighing (before) by balance
Filter setting to the sampler
Perform Sampling 24 hrs
Sampling Remove and collect the filter
sample
Sample drying and
Sample conditioning (200C, 50% R.H),
Measurement 48 hrs
Weighing (after) by balance
Calculate the concentration
and store the sample
29. Calculations
Initial wt. of filter paper Wi= ----- g
Wt. of filter paper + particulate matter Wf= ------ g
Wt. of Particulate matter W= (Wf – Wi) X 106 µg
Avg. flow rate over the entire duration of sampling
period Qavg= ----- L/min
Duration of the sampling period t= ----- min
Total sample volume V= Qavg X t X 10-3 m3
Concentration of particulate matter PM 10/2.5
C = W / V = ----- µg/m3
30.
31.
32.
33.
34.
35.
36. Sample
Preparation for HCl (1+1) 30mL
Metal Analysis H2O2 (30%) 5mL
of HV Filter 120 C, 1Hr in a draft chamber
Samples Funnel / Whatman 41 Filter Paper
soon before dry up
HNO3 (2+98)
after cooling
HNO3 (2+98)
Polyethylene Bottle
37.
38. Calculation of Lead Concentration in Air (AAS)
C= (c1-cb) X v X (S/s) / Vo (µg/m3)
where
c1: Pb concentration in the solution of sample
cb:Pb concentration in the solution of blank
filter (µg/mL)
v: Sample solution volume (25 mL)
S/s: Ratio of Sampled filtered area by the
analyzed area
Vo: Sampling air volume at standard cond.
Vo = V X 298 / T (m3)
V: Sampling air volume at present state (m3)
T: Average Temperature during sampling (K)
45. Acid Rain / Acid Deposition
Acid deposition occurs when emissions of
sulfur dioxide and nitrogen oxides in the
atmosphere react with water, oxygen, and
oxidants to form acidic compounds
These compounds fall to the earth in either
dry form (gas and particles) known as Dry
Deposition or wet form (rain, snow, and fog)
known as Wet Deposition
Duration of the reaction
It takes days or weeks for atmospheric SOx
and NOx to be converted to acids and
deposited on the earth's surface, acid
deposition occurs in a multistate scale
hundreds of miles away from its sources
52. Smog
Smog is thick, choking,
dangerous. It happens when
tiny particles of dust, smoke
and dangerous gases like
sulfur dioxide mix with
water vapor. And it’s no
accident: it is all carefully
manufactured by one species
– human beings!
57. Dispersion of Air Pollutants
Coning
A coning plume occurs under essentially neutral
stability, when environmental lapse rate is equal
to adiabatic lapse rate, and moderate to strong
winds occur. The plume enlarges in the shape of
a cone. A major part of pollution may be carried
fairly far downwind before reaching ground.
58. Dispersion of Air Pollutants
Looping
Under super-adiabatic condition, both upward
and downwind movement of the plume is
possible. Large eddies of a strong wind causes
looping pattern. Although large eddies tend to
disperse pollutants over a wide region, high
ground level concentrations may occur close to
the stack.
59. Dispersion of Air Pollutants
Fanning
A fanning plume occurs in the presence of a
negative lapse rate when vertical dispersion
is restricted. The pollutants disperse at the
stack height, horizontally in the form of a
fanning plume.
60. Dispersion of Air Pollutants
Lofting
When the stack is sufficiently high and the
emission is above an inversion layer, mixing in
upper layer is uninhibited, but downward
motion is restricted. Such lofting plumes do
not result in any significant concentration at
ground level. However, the pollutants are
carried hundreds of kilometers from the
source.
61. Dispersion of Air Pollutants
Fumigation
When the emission from a stack is under an
inversion layer, the movement of the pollutant
in the upward direction is restricted. The
pollutants move downwards. The resulting
fumigation can lead to a high ground level
concentration downwind of the stack.
63. Inversion Layer
In meteorology, the
atmospheric layer in
which the usual
temperature gradient—
warm air below cold air—
is reversed, preventing
the mixing of warm and
cold air as the warmer air
rises. This traps
dangerous concentrations
of pollutants in the cool
air below, sometimes
causing dense smog over
urban areas.
65. NEQS for Ambient Air
Standards for the
minimum ambient air
quality needed to protect
public health and welfare
which are applicable to
the ambient air all over
Pakistan
66. National Environmental Quality
Standards NEQS for Ambient Air
Pollutants Time-weighted Concentration in
average Ambient Air
Effective from 1st
January, 2009
Sulfur Dioxide Annual Average 80 µg/m3
24 hour 120 µg/m3
Oxides of Nitrogen as Annual Average 40 µg/m3
NO 24 hour 40 µg/m3
Oxides of Nitrogen as Annual Average 40 µg/m3
NO 24 hour 80 µg/m3
Ozone 1 hour 180 µg/m3
Suspended Particulate Annual Average 400 µg/m3
Matter 24 hour 550 µg/m3
SPM
Particulate Matter Annual Average 200 µg/m3
PM10 24 hour 250 µg/m3
Particulate Matter Annual Average 25 µg/m3
PM2.5 24 hour 40 µg/m3
1 hour 25 µg/m3
Lead (Pb) Annual Average 1.5 µg/m3
24 hour 2.0 µg/m3
Carbon Monoxide (CO) 8 hour 5 mg/m3
1 hour 10 mg/m3
67. Attainment Area /
Non-Attainment Area
Attainment Area
An area considered to have air quality as good
as or better than the National Environmental
Quality Standards as defined in the draft by
Pak-EPA.
Non-Attainment Area
An area that does not meet one or more of the
National Environmental Quality Standards as
defined in the draft.
An area may be an attainment area for one
pollutant and a non-attainment area for
others.