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Lecture 10. Lecture 11. Air & Noise Pollution. The Atmosphere. thin , gaseous envelope of air around Earth we live at the bottom of this sea of air. The atmosphere is divided into the:. Troposphere. atmosphere’s inner layer contains most of Earth’s air

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Lecture 11

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Lecture 11 l.jpg

Lecture 10

Lecture 11

Air & Noise Pollution

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The Atmosphere

  • thin, gaseous envelope of air around Earth

  • we live at the bottom of this sea of air

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The atmosphere is divided into the:

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  • atmosphere’s inner layer

  • contains most of Earth’s air

  • N2 ( 78% ), O2 ( 21% ), CO2 ( 0.04% )

  • weather occurs here

  • temperaturedrops with an increase in altitude

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  • layer above troposphere

  • temperature rises with altitude

  • our global sunscreen

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  • contains O3“good ozone”

  • ozone layer prevents99% of harmfulultraviolet radiation from reaching Earth’s surface

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Ozone in the Troposphere(Pollutant)

Trace amounts of O3that form in the troposphere as a component of urban smog cause damage to:


•materials, e.g., rubber

•respiratory systems of humans & other animals

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What is Air Pollution?

  • one or more chemicals in high enough concentrations in the air to:

    1)harmorganisms or materials

    2)alter climate

  • these chemicals are called air pollutants.

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Sources of Air Pollution

  • Natural events

    (e.g., volcanic eruptions, dust storms)

    2.Human activities

    (e.g., emissions from cars and smoke stacks)

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Major Air Pollutants

  • Carbon Dioxide (CO2)

  • linked to global warming

    2.Sulfur Dioxide (SO2)

  • Linked to global warming, acid deposition

    3.Nitrogen Oxides

  • Linked to global warming

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Major Classes of Air Pollutantscont’d

4.Volatile Organic Compounds

- e.g., methane, propane, benzene, chlorofluorocarbons (CFCs)

  • found in paints and protective coatings

  • have long-term health risks including:

  • compromised immune system in infants

  • respiratory disorders

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Major Classes of Air Pollutantscont’d

5.Suspended Particles

- e.g., solid particles (dust, asbestos, soot)

- e.g., liquid droplets (pesticides, sulfuric acid)

- linked to respiratory disorders

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Types of Air Pollutants

Primary Pollutant

- chemical, that occurs in a harmful concentration, added directly to the air by natural events or human activities

e.g. sulphur dioxide, carbon monoxide, carbon dioxide

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Types of Air Pollutantscont’d

Secondary Pollutant

- harmful chemical formed in atmosphere when a primary air pollutant reacts with the normal air components or with other air pollutants

e.g. ozone, sulphur trioxide

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Urban Air Pollution


- originally a combination of smoke & fog

- now describes other mixtures in the atmosphere

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Urban Air Pollutioncont’d

Industrial Smog

- consists mainly of a mixture of sulfur dioxide, suspended droplets of sulfuric acid and a variety of suspendedsolid particles

- found in cities that burn large amounts of coal and heavy oil which contain sulfurimpurities

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Effects of Climate & Topography on Air Pollution

  • Areas with high average annual precipitation, help cleanse the air of pollutants.

  • Winds help sweep pollutants away and bring in fresh air.

  • Hills & mountainsreduce the flow of air in valleys below and allow pollutant levels to build up at ground level.

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Effects of Climate & Topography on Air Pollutioncont’d

  • Buildings in cities slow wind speed & reduce dilution and removal of pollutants.

  • The process of hot air rising and cold air sinking causing continual mixing of air, helps keep pollutants from reaching dangerous levels near the ground.

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Temperature Inversion

  • also called thermal inversion

  • a layer of warm air settles over a layer of cooler air that lies near the ground.

  • the warm air holds down the cool air and prevents pollutants from rising and scattering allowing them to build up to harmful levels

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Smoke rising in Lochcarron, Scotland is stopped by an overlying layer of warmer air – thermal inversion

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Acid Deposition

  • the falling of acids and acid-forming compounds from the atmosphere to the earth’s surface

  • commonly known as acid rain

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Acid Rain

  • refers only to wetdeposition of droplets of acids and acid-forming compounds

  • natural precipitation is slightly acidic (pH 5.0-5.6)

  • acid rain can have a pH of 4.3 or 3 (as acidic as vinegar)

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Harmful Effects of Acid Deposition

  • contributes to human respiratory diseases

  • damages foliage and weaken trees

  • contaminate fish

  • damages statues, buildings, metals, & car finishes

  • releases aluminium ions which damage tree roots

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Greenhouse Effect

  • natural effect that traps heat in the troposphere

  • some of the heat flowing back toward space from Earth’s surface is absorbed, by H2O vapour, CO2, O3 and other gases, then radiated back toward Earth’s surface

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Greenhouse Gases

  • gases in the troposphere that cause the greenhouse effect

  • include:

    carbon dioxide

    chlorofluorocarbons (CFCs)



    water vapour

    nitrous oxide

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Greenhouse Gasescont‘d

  • the 2 predominant greenhouse gases are:

    • water vapour

    • carbon dioxide

  • if the atmospheric concentrations of these gases increase, the average temperature of the troposphere will gradually rise

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    • warming of atmosphere due to increases in the concentrations of one or more greenhouse gases primarily as a result of human activities, mainly:

      burning of fossil fuels

      use of CFCs



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    Global Warmingcont’d

    In recent decades certain greenhouse gases have increased in concentration:

    carbon dioxide


    nitrous oxide


    CO2 contributes to ~ 55% of global warming.

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    Global Warmingcont’d

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    Possible Impacts of Global Warming on Caribbean States

    • disastrous for ecosystems e.g. coral reefs (coral bleaching)

    • alter climatic conditions faster than some species could adapt

    • shift food-growing areas

    • rise in sea levels due to melting of icecaps and glaciers may flood coastal settlements

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    Meltwater from Ice Sheet in Greenland flowing into ocean


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    Possible Impacts of Global Warming on Caribbean Statescont’d

    • more frequent and fiercehurricanes

    • disastrous for economic and social systems

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    Ozone Layer

    • layer of gaseous ozone that protects life on Earth by filtering out harmful ultraviolet radiation from the sun

    • being depleted by CFCs, halons and other chemicals

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    • Chlorofluorocarbons

    • used in air conditioners, refrigerators, aerosol spray cans, cleaners for electronic parts, hospital sterilants, fumigants, plastic foam

    • ozone eaters

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    Impact of Ozone Depletion

    • increased cases of cancer & cataracts

    • suppression of human immune system

    • lowers crop yield

    • degradation of materials

    • reduction in phytoplankton

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    Noise Pollution

    - any unwanted, disturbing or harmfulsound that impairs or interferes with hearing, causes stress, hampers concentration and work efficiency or causes accidents

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    Impact of Noise Pollution

    • permanent hearing loss

    • hypertension

    • insomnia

    • irritability

    • migraine headaches

    • muscle tension

    • gastric (stress) ulcers

    • psychological disorders (eg, increased aggression)

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    • enforceair & noise pollution laws

    • use emission control devices

    • ban or limit smoking to well-ventilated areas

    • tax each unit of pollution produced

    • use office machines in well-ventilated areas

    • shift to less polluting energy sources

    • increase intake of outdoor air

    • car exhaust inspections

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