Environmental Geology: Types, Causes, Effects, and Control of Air Pollution.

1. Air Pollution
Presented by:
Muhammad Talha (43)
BS Applied Geology 3rd Prof. (Morning)
Session: 2016-20
Institute of Geology, University of the Punjab, Pakistan
Presented to: Dr. Sanaullah Sani

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Pollution means “change in background concentration.”
“Any substance introduced into environment that adversely affects the usefulness of a
resource”
Pollution happens because no process is 100% efficient; each process produces pollution.

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Sources
A. Natural: Volcanoes, wildfires, microbs, dust, pollens, spores etc.
B. Anthropogenic (Man-made): Power plants, automobiles, fumes, stoves, fireplaces,
burning wood, furnaces, smoking, explosions, mining, industries etc.
Sources can also be categorized as; (a) point vs area (b) mobile vs stationary (c)
indoor vs outdoor
Anthropogenic sources contribute <0.1% to total air pollution.
Air pollution is most common in large cities where emission from many different
sources are concentrated.

4. Pollutant
A substance dwelling temporarily or permanently in air which alters environment by interfering with
health, comfort, food chain, or property values.
Pollutants can be grouped into two categories:
 Primary – emitted directly from source
Particulate matter (PM), Sulfur dioxide, nitrogen oxides, volatile organic compounds (VOCs),
carbon monoxide, carbon dioxide and lead.
 Secondary – produced in atmosphere when certain chemical reaction take place among primary
pollutants.
Sulfur trioxide, nitric acid, sulfuric acid, hydrogen peroxide, ozone, PANs, nitrogen trioxide and
sulfate salts.

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Effects
Air pollution affects living as well as non living matter.
Effects on Human:
• Respiratory, dermal and optical diseases.
• Air pollution contributes around 30-40% of asthma cases and 20-30% of all respiratory diseases.
• Short term effects: irritation to nose, eye, throat, bronchitis, headache etc.
• Long term effects: lung disease, chronic respiratory problem, damage to heart, brain and eyes.
• NOx, ozone, PAN and particulates cause eyes irritation.
• Sulfur dioxide and NOx cause nasal and throat irritation.
• Respiratory diseases include emphysema, bronchitis, asthma, pneumonia, lung cancer.
• CO and NO reduces oxygen carrying capacity of hemoglobin in RBCs. Also cause decrease in vision and cardio
vascular disorders.
• Heavy metals like lead can cause poisoning. High concentration cause damage to liver and kidney.

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Effects on Plants:
• Decreased yield in agriculture.
• Suppressed growth of vegetables.
• Leaf injury and damage to young plants.
• Decreased growth rate and increased death rate.

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Effects on Non-living matter:
• Air pollutants dissolve in rain water to make it acidic. Which then damages matter.
• Corrosion of metals due to sulfur dioxide in presence of oxygen and moisture is converted into sulfuric
acid.
• Sulfuric acid weathers carbonate rocks (limestone, dolostone)
• Sulfur dioxide, ozone, hydrogen sulfide and aerosols damage paints and protective coatings.
• Ozone and PAN causes cracking of rubber and various electrical insulations.
Atmospheric and environmental affect:
• Air pollution deteriorates crop/forest and wildlife.
• Produces haze and eutrophication.
• Depletes ozone and changes global climate.

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Control
Can’t be fully prevented but can be controlled.
Preventative measures (source control):
• Selection of suitable fuel: low sulfur coal in power plant, using of CNG.
• Modification in industrial process.
• Selection of suitable site and zoning for industrial unit.
Control measures (using equipment):
• When source control not possible some measures taken to prevent pollution.
• Collecting pollutants by using equipments.
• Destroying pollutant (e.g by thermal or catalytic combustion)
• Transforming pollutants to less toxic form.
• Release of pollutants through tall chimneys for greater dispersion.

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Air pollution control equipments
Gravitational settling chamber:
used to remove particles with size greater than 50 µm. Velocity of flue gas is reduced in last chamber. Particles
settle under gravitational force.
Advantages
• Low initial cost
• Easy to design
• Low pressure drop
• Low maintenance cost
• Dry and continuous disposal of solid particulates
Disadvantages
• Require large space
• Less collection efficiency
• Only larger size particles can be collected

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Cyclone separator:
Centrifugal force is utilized to separate the particulate matter. It can remove 10 to 50 µm particulates. Used mostly
in industries.
Advantages
• Low initial cost
• Require less floor area
• Simple construction and maintenance
• Can handle large volume of gas at high temp.
Disadvantages
• Requires large head room
• Less efficiency for smaller particles (<10µm)
• Sensitive to variable dust load and flow rate.

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Electrostatic precipitator:
Works on principle of electrical charging of particulate
matter (-ve) and collecting it in a +ve charged surface.
It has 99% efficiency and can remove particle size
range of 0.1 to 1 µm.
Advantages
• High collection efficiency
• Particles may be collected dry or wet
• Can be operated at high temp. (300-450°C)
• Maintenance is normal
• Few moving parts
Disadvantages
• High initial cost
• Require high voltage
• Collection efficiency reduce with time
• Space requirement is more
• Possibility of explosion during collection of
combustible gases or particulates

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Fabric filter:
Flue gas is allowed to pass through a woven fabric, which
filters out particulates. Small particles are retained on the
fabric. Its efficiency is upto 99% and removes particles
upto 1 µm.
Advantages
• Higher collection efficiency for smaller then 10 µm
particle size
• Performance decrease becomes visible, giving
prewarning
• Normal power consumption
Disadvantages
• High temp. gases need to be cooled
• High maintenance and fabric replacement cost
• Large size equipment
• Fabric is liable to chemical attack

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Scrubbers:
Particulate matters are incorporated into liquid droplets and removed from the gas stream. Different types of
scrubbers are:
o Spray tower
o Venturi scrubber
o Cyclone scrubber
Flue gas made to push up against a down falling water current. Particulate matter mix up with water thus falls down
and gets removed.
Advantages
• Simultaneously remove particulates and gaseous pollutants
• Hot gases can be cooled down
• Corrosive gases can be recovered and neutralize
Disadvantages
• Lot of waste produced
• Poses freezing problem in cold countries
• Maintenance cost is high when corrosive materials are collected.

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17. Thank you!
“Be a part of solution! not
part of pollution.”
References:
 AIR POLLUTION By Bibhabasu Mohanty Assistant Professor Department of Civil Engineering SAL
Institute of Technology & Engineering Research
 https://www.nationalgeographic.org/encyclopedia/air-
pollution/?fbclid=IwAR3YEznvopJy6fZtQovDnsCFsCnozxjezvhMys1ekthmi3y5wpYoM--yyI4
 Text book 10th biology PTBB.