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AIR POLLUTION

BY

DR. SHAHEDA NILOUFER

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ENVIRONMENTAL POLLUTION

Any change in the environment which contributes to its deterioration is called pollution.
And the agent that causes pollution is called a pollutant.

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AIR POLLUTION

Defined as “Presence in atmosphere of any solids, liquids and gasses in concentrations that may tend to be injurious to human health, health of desirable species, plants, properties and enjoyment” (Air Amendment Act, 1987)

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The composition of Air is given below:

Nitrogen 78%�Oxygen 21%�Argon less than 1%�Carbon dioxide 0.037%�Water vapour Remaining�Ozone, Helium and ammonia Trace amount �

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Natural: forest fires, pollen, dust storm

Unnatural: man-made; coal, wood and other fuels used in cars, homes, and factories for energy

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Sources of Air Pollution

Stationary Combustion Sources
Oxides of Carbon: CO, CO2
Oxides of Sulphur: SO2,SO3
Oxides of Nitrogen: NO,NO2
Hydrocarbons (HC’s) and VOC’s

Mobile Combustion Sources
Gaseous Pollutants: CO, NOX, HC’s
Particulate lead
Benzopyerene
Aerosols: CFC’s

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Classification

Primary pollutants: The Pollutants that exist in the same form in which they are released.

Carbon dioxide

Sulphur oxides etc

Secondary pollutants: Some Pollutants in the Atmosphere Combine to Form Other Pollutants.

Photochemical Smog

Acid Rain etc

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Fig. 18-4, p. 472

Primary Pollutants

CO

CO₂

Secondary Pollutants

SO₂

NO

NO₂

Most hydrocarbons

SO₃

Most suspended particles

HNO₃

H₂SO₄

H₂O₂

O₃

PANs

Sources

Natural

Stationary

Mobile

Most NO₃⁻ and SO₄²⁻ salts

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What Are the Major Outdoor Air Pollutants?

Carbon oxides

Carbon monoxide (CO)
Carbon dioxide (CO₂)
Sources
Human health and environmental impact

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What Are the Major Outdoor Air Pollutants?

Nitrogen oxides (NO) and nitric acid (HNO₃)

Sources
Acid deposition
Photochemical smog
Human health and environmental impact

Sulfur dioxide (SO₂) and sulfuric acid (H₂SO₄)

Sources
Human health and environmental impact

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What Are the Major Outdoor Air Pollutants?

Particulates

Suspended particulate matter (SPM)

Fine
Ultrafine

Sources

Human health and environmental impact

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What Are the Major Outdoor Air Pollutants?

Ozone (O₃)

Sources
Human and environmental impact

Volatile organic compounds (VOCs)

Hydrocarbons and terpenes
Sources
Human and environmental impact

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Chemical Reactions That Form Major Outdoor Air Pollutants

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Several Factors Can Decrease or Increase Outdoor Air Pollution

Outdoor air pollution may be increased by

Urban buildings
Hills and mountains
High temperatures
Emissions of VOCs from certain trees and plants
Grasshopper effect
Temperature inversions

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AQI: Air Quality Index

Indicates whether pollutant levels in air may cause health concerns.
Ranges from 0 (least concern) to 500 (greatest concern)

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Air Quality	Air Quality Index	Protect Your Health
Good	0-50	No health impacts are expected when air quality is in this range.
Moderate	51-100	Unusually sensitive people should consider limiting prolonged outdoor exertion.
Unhealthy for Sensitive Groups	101-150	Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.
Unhealthy	151-200	Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion, everyone else, especially children should limit prolonged outdoor excertion.
Very Unhealthy (Alert)	201-300	Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion everyone else, especially children, should limit outdoor exertion.

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5 Major Pollutants:

1..) Carbon Monoxide

2.) Sulfur Dioxide

3.) Nitrogen Dioxide

4.) Particulate Matter

5.) Ground Level Ozone

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Carbon Monoxide

colorless, odorless
produced when carbon does not burn in fossil fuels
present in car exhaust
deprives body of O2 causing headaches, fatigue, and impaired vision

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Sulfur Dioxide

produced when coal and fuel oil are burned
present in power plant exhaust
narrows the airway, causing wheezing and shortness of breath, especially in those with asthma

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Nitrogen Dioxide

reddish, brown gas
produced when nitric oxide combines with oxygen in the atmosphere
present in car exhaust and power plants
affects lungs and causes wheezing; increases chance of respiratory infection

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Particulate Matter

particles of different sizes and structures that are released into the atmosphere
present in many sources including fossil fuels, dust, smoke, fog, etc.
can build up in respiratory system
aggravates heart and lung disease; increases risk of respiratory infection

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Ground Level Ozone

at upper level, ozone shields Earth from sun’s harmful UV rays
at ground level, ozone is harmful pollutants
formed from car, power and chemical plant exhaust
irritate respiratory system and asthma; reduces lung function by inflaming and damaging lining of lungs

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Combination of gases with water vapor and dust

Combination of words smoke and fog

Forms when heat and sunlight react gases (photochemical smog)

Occurs often with heavy traffic, high temperatures, and calm winds

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1^st smog related deaths were in London in 1873; death toll 500 people; can you imagine how much worse the atmosphere is now?!
Limits visibility
Decreases UV radiation
Yellow/black color over cities
Causes respiratory problems and bronchial related deaths

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Effects on Plants

Necrosis: Killing or collapse of the tissues of plants. (Fluorides, Acid rains)

Chlorosis: Reduction of chlorophyll.

(SOX, PAN, Smog)

Abscission: Dropping of leaves. (HC’s)
Epinasty: Downward curvature of the leaves due to excessive growth on the upper surface

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EFFECTS ON MATERIALS

Air pollution causes effect to materials by five mechanisms
Corrosion
Abrasion
Deposition and removal
Direct chemical attack
indirect chemical attack

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Effects of air pollution

Acid rains
Global warming
Ozone depletion

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Control of Air Pollutants

1. Source correction methods

Substitution of raw materials
Process modification
Modification of existing equipments
Maintenance of equipments

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2. Diffusion of pollution in air

3. Zoning

4. Vegetation

5. Control Equipments

6. Acts

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Control equipments

Gaseous Control Particulate Control

Absorption Adsorption Gravitational Settling Chamber

Cyclonic Separator

Fabric Filter

Electrostatic Precipitator

Scrubbers (Wet Collectors)

Spray Tower

Venturi Scrubber

Cyclonic Scrubber

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Multi Cyclone Mechanical collector

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Cyclones

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Baghouse Filter

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Bag Filter or Bag House

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Fabric Filters

Fabric Filter

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Electrostatic Precipitator (ESP)

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Electrostatic Precipitators

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Electrostatic Precipitators

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Spray Tower or Scrubber

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Wet Scrubber

Venturi Scrubber

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Venturi Scrubbers

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Venturi Scrubber

Aerosol & Particulate Research Lab

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2023/11/17

Handbook of Air Pollution Control Engineering & Technology, Mycock, McKenna & Theodore, CRC Inc., 1995.

High efficiency even for small particles

Q: ESP for sticky, flammable or highly corrosive materials?

Q_L/Q_G: 0.001 - 0.003

V_G: 60 - 120 m/s

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Cyclone Spray Chamber & Impingement Scrubber

Aerosol & Particulate Research Lab

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Flagan & Seinfeld, Fundamental of Air

Pollution Engineering, 1988

Q: Is used water recirculated?

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Spray Chamber

Aerosol & Particulate Research Lab

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Recirculated water

Water to settling basin and recycle pump

Vertical spray chamber (countercurrent flow)

Collecting medium:

Liquid drops
Wetted surface

Q: What parameters will affect the collection efficiency?

Q: Any other arrangement of air & water?

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The Air (Prevention and Control of Pollution) Act - 1981

1981 - The Air (Prevention and Control of Pollution) Act

Enacted under article 253 of the Indian constitution.
Provides for the control and abatement of air pollution.

In the Act, air pollution has been defined as the presence of any solid, liquid or gaseous substance (including noise) in the atmosphere in such concentration as may be or tend to be harmful to human beings or any other living creatures or plants or property or environment.