Air and Noise Pollution

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Air and Noise Pollution

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    ATMOSPHERE

    The atmosphere is an envelope of gases that surrounds the earth. The air we breathe is the

    part of atmosphere. Scientists have divided the atmosphere into four main parts, each with its own

    characteristics. They are:

    1. Troposphere

    2. Stratosphere

    3. Mesosphere

    4. Thermosphere

    1. Troposphere:

    The layer of atmosphere that touches the surface of earth is called Troposphere. The

    troposphere extends to a height of about 8 to 18 kilometers above the surface of earth.

    Most of the living organisms come under troposphere. This layer contains most of the water

    vapors in the atmosphere and this is only the layer in the atmosphere where weather changes occur.

    2. Stratosphere:

    Beyond the troposphere, reaching at a height of about 50 kilometers above the surface of

    earth is Stratosphere. Most jet planes travels in the lower level of stratosphere. The upper level of

    stratosphere contains a layer of gases called OZONE.

    3. Mesosphere:

    After the layer of stratosphere, there is another layer called Mesosphere which is extended

    up to 85 kilometers above the surface of earth. The mesosphere is the coldest layer of the

    atmosphere. Its temperature can be as low as -100 oC.

    4. Thermosphere:

    Thermosphere is the most outer layer of atmosphere. Unlike the mesosphere, thermosphere

    has a very high temperature reaching up to 2000 oC

    Biosphere:

    The living environment, known as biosphere consist of Land (Lithosphere), Water

    (Hydrosphere) and Air (Atmosphere) is the basic layer to sustain Food and

    .

    AIR POLLUTION

    (1) Air:

    Atmosphere is the column of air that surrounds the earth, starting from the surface of earth

    to the altitude of 18 Km called Troposphere. Air is blanket of gases that contain:

    Nitrogen 78.09% by volume, Oxygen 20.94% by volume and other gases like Carbon, Argon,

    Neon, Helium, Methane, etc. These are in pure and perfect harmony.

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    (2) Pollution:

    Air polluted due to the presence of one or more than one contaminant present in the air in

    sufficient quantity, composition and characteristics which causes injury to life as well as damages

    the materials and properties.

    Organic are: Methane, Benzene, formaldehyde, chlorinated hydrocarbons

    AND

    Inorganic are: NOX, SOX, COX, H2S, HF, NH3.

    (3) Control:

    A. Naturally self cleansing way of the environment

    1. Dispersion

    2. Gravitational settling

    3. Natural Absorption process

    4. Rain out

    5. Adsorption

    B. Controlling Air Pollution source through engineering devices.

    1. Stationary Source and

    2. Mobile Source

    Stationary Source:

    a. Absorption

    1a.) - Wet Scrubbers

    2a.) - Dry Scrubbers

    b. Combustion

    c. Fuel Gas Desulphurization

    d. Particulate Pollutants

    Mobile Sources:

    a. Fundamentals of different available engines

    b. Control

    Dispersion:

    Dispersion of pollutants by winds reduces the concentrations of air pollutants by moving the

    smog from one place to another. This diluted the smoke but not remove it.

    To calculate it mathematically a model has been developed to estimate the concentration of

    the particular pollutant for the specific location and time.

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    Gravitational Settling:

    Gravitational Settling is the most important natural mechanism under which large particles

    from the ambient air settle down on the buildings, trees and other objects.

    This process helps in removing large amount of particles formed by uniting of the smaller

    particles over the large particles, till the united particles becomes large and heavy enough to settle

    down under the gravity.

    Natural Absorption Process:

    The gaseous as well as particulates pollutants from the air get collected in rain or mist and

    settle down with that moisture. This phenomenon takes place below the cloud level, when falling

    rain drops absorb pollutants also known as wash out or scavenging.

    This does not remove particles less than 1 micro meter. The gaseous pollutants are removed

    in dissolved state with moisture either with or without chemical damages.

    Rainout:

    In this process precipitation in the clouds where sub micro particles in the atmosphere in the

    clouds serve as a condensation nuclei around which drops of water may form and fallout as rain

    drops. This increases the rainfall and fog formation in the urban areas.

    Adsorption:

    This is the phenomenon in which gaseous or the liquids pollutants present in the ambient air

    we kept attracted, generally electro statically by a surface where they are concentrated and retained.

    Natural surface such as soil, rocks, leaves, and blades of grass, buildings and other objects

    can absorb and retain pollutants. The particles may come in contact with such surfaces either by

    gravitational settling or by internal impaction.

    Absorption:

    Control devices work on the principle that they absorb and transfer the pollutant smoke

    from gas to the liquid state.

    It is a mass transfer process in which gas is dissolved in the liquid. This conversion may or

    may not accompanied by a reaction with water.

    This is purely a diffusion process where pollutants move from higher concentration to the

    lower concentration.

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    Scrubbers:

    It is one of the most common pollution control device used by the industries. It is operated

    on a very simple principle that the polluted gas is brought into contact with the absorbent so that the

    pollutants can be removed.

    There are two types of Scrubbers: Wet Scrubbers and Dry Scrubbers. Mechanism of both

    the scrubbers is almost same. The only difference is in case of Dry Scrubbers End Product is in

    solid form while in case of Wet Scrubbers it is found in liquid form.

    Combustion:

    When the contaminant in the gas is oxidize able to an inert gas than combustion for

    contaminant control is used.

    There are two methods are used commercially as:

    1) Direct Flume Combustion

    2) Catalytic Combustion.

    Direct flume combustion:

    This method used when:

    1) The gas stream must have an energy concentration greater than 3.7 MJ/m3. At this

    concentration the gas flume will be self supporting after ignition, below this point the

    supplementary fuel is required.

    2) None of the by-products of combustion be toxic.

    In some cases the combustion byproducts may be more toxic than the original pollutant gas. For

    example the combustion of trichloroethylene will produce Phosgene, which was used as a war gas

    in World War I.

    Direct flume applied to Varnish cooking, meat smoke house and paint bake oven emission.

    Catalytic Combustion:

    Some catalytic materials enable oxidation to be carried out in gases that have an energy less

    than 3.7 MJ/m3.

    Active catalyst is a platinum or Palladium compound.

    Supporting lattice is usually a Ceramic.

    These are expensive, liable to poisoning by sulfur and lead compounds in trace amounts.

    Catalytic combustion has successfully applied to printing press, varnish cooking and asphalt

    oxidation emission.

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    Fuel Gas Desulphurization (FGD):

    The technology that employs absorbent, usually lime or limestone, to remove SO2 from the

    gases produced by burning fossil fuels. Flue gas desulphurization is the current technology for

    major SO2 emitters, like power plants.

    Lime is used to remove SO2 from coal fired power station gases (called FGD) the product is

    Gypsum.

    CaO(s) + SO2 (g) + 2H2O (1) + O2 (g) CaSO4. 2H2(s)

    This system may used with the scrubbers or in the towers through two broad ways.

    Regenerative (Reusable)

    Non regenerative. (Not reusable)

    In terms of the number and size of system installed, the non-regenerative system dominates.

    Cyclone:

    For particle size greater than above 10 um, the collector of choice is the cyclone.

    This is inertial collector with no moving parts.

    The particulate gas is accelerated through a spiral (round) Motion, which imparts a

    centrifugal force to the particles. Due to which the particles by force come out of the gas and

    impact on the cylinder wall of the cyclone. Then they slide to the bottom of the cone, where they

    are removed through an air tight valving system.

    The efficiency of collection of various particle sizes can be determined through an

    expression given below.

    [(9 B2 H)]

    d0.5=

    [p Qg ]

    As the diameter of the cyclone is reduced, the efficiency of collection increased, pressure

    drop also increases which ultimately increases the power requirement for moving the gas through

    the collector.

    With the increase in the efficiency tangential velocity remains constant and the efficiency

    increases with increase in the power consumption by using multiple cyclones in parallel.

    Filter:

    When the high efficiency controls of particles smaller than 5um are desired than we use

    filters.

    There are two types of filters in use 1 deep bed filters 2 the bag house.

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    The deep bed filters resembles like a furnace filter, having packing of fibers used to block

    the particles of the gas stream, used in air conditioners.

    For the dirty industrial gas, we have the bag house filters, made of cloth fabric. Their

    diameter range from 0.1 to 0.35 m and their length vary b/w 2 6 m.

    AIR POLLUTANTS

    Due to natural and man-made pollution, the air is never found clean in the atmosphere.

    Gases such as CO, SO2 and H2O are continuously releases into the atmosphere through natural

    activate (Volcanic activity, Vegetation decay and Forest fires). Tiny particles of solids and liquids

    are distributed throughout the air by winds, volcanic explosion and other similar natural

    disturbances. In addition to these natural pollutants, there are man-made pollutants also which

    hardly exist beyond 21000 feet above ground level.

    Air pollutants may be Natural and Man-made pollutants; these are also classified in to two

    categories: as Primary Pollutants and Secondary Pollutants.

    PRIMARY AIR POLLUTANTS:

    Those pollutants that are emitted directly from the source and are found in the atmosphere

    in the form in which they were emitted are called Primary Pollutants. Primary air pollutants are

    formed else where and discharged as such into the air.

    SECONDARY POLLUTANTS:

    Secondary air Pollutants are formed in the air were primary air pollutants react with each

    other. Sulfur dioxide (SO2) is a primary air pollutant that forms when fossil fuel is burned. In the air

    it may react with oxygen gas to form secondary pollutant sulfur trioxide. 2SO2 + O2 2SO3

    This is turn may react with water vapor in the air to form another secondary air pollutant,

    i.e., sulfuric acid (H2SO4). SO3 + H2O H2SO4.

    This is one of the substances that can make rain acidic. There are so many sources of air

    pollutants but they are classified in to two groups.

    i)- Natural

    ii)- Man-made or Anthropogenic

    I) - Natural Source:

    Natural factor include metrological and sometimes geographical conditions restrict the

    normal dilution of contaminant. There are many naturally occurring air borne materials such as

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    from flower, gas from decaying matter, micro organisms, particulates from nature forest fires, dust

    storms, and volcanic eruptions. The natural factors usually beyond mans sphere of control

    II) - Man-made Source/ Anthropogenic Sources:

    The man made factors are also referred as an Anthropogenic Sources. They include

    industrial processing, Vehicular usage, Power generation, nuclear explosions and other man made

    polluted use radio active isotopes.

    IMPORTANT PRIMARY AIR POLLUTANTS ARE:

    Sulfur Oxides (SOX), particularly Sulfur dioxide (SO2)

    Carbon Mono Oxide (CO)

    Nitrogen Oxides (NOX)

    Lead

    Hydrocarbons both Aliphatic and Aromatic

    Allergic Agents like Pollens and Spores

    Radio Active substances

    Hydrogen Sulfide

    Hydrogen Fluoride

    Methyl and ethyl meraptans

    IMPORTANT SECONDARY AIR POLLUTANTS ARE:

    Sulfuric Acid (H2SO4)

    Ozone (O3)

    Formaldehydes

    Peroxy Acyl Nitrate (PAN)

    SOURCES OF SOME IMPORTANT AIR POLLUTANTS AND THEIR EFFECTS:

    Pollutant: Carbon Mono Oxide (CO)

    Major Source: Incomplete combustion of fuel, automobile exhaust, jet engine emission, mines

    and tobacco smoking.

    Effects: Toxicity (poisonous) caused blood poisoning.

    Pollutant: Sulfur dioxide (SO2)

    Major Source: Combustion of coal, Combustion of Petroleum products, Oil Refinery, Power

    House (Coal), Sulfuric Acid Plants, and Domestic burning fuels

    Effects: Increasing the breathing rate, Suffocation, asthma, Irritation of eyes.

    Pollutant: Nitrogen Oxide (NOX)

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    Major Source: Automobile exhaust, Gas fire furnace, Fertilizer Industry.

    Effects: Respiratory Irritation, Headache, Corrosion of Teeth

    Pollutant: Carbon dioxide (CO2)

    Major Source: Combustion of Fuel, Jet engine emission.

    Effects: Toxic in large quantities.

    Pollutant: Hydrocarbons (HC)

    Major Source: Organic Chemical Industry, Petroleum Refinery

    Effects: Cancer

    Pollutant: Ammonia (NH3)

    Major Source: All chemical Industries

    Effects: Aspiratory System, Eyes Irritation

    Pollutant: Formaldehyde (NCHO)

    Major Source: Combustion of Fuel, Photo Chemical Reaction

    Effects: Irritation of eyes, Skin, Aspiratory.

    Pollutant: Hydrogen Sulphide (H2S)

    Major Source: Petroleum Industry, Coal Ovens, Oil refinery, Sewage Treatment Plant

    Effects: Headache, Eyes pain, Irritation Aspiratory.

    ACID RAIN Acid Rain or more precisely acid precipitation is the word used to describe Rain-fall that

    has pH level less than 5.6. But in broader sense Acid Rain is a term used to describe several

    ways that acids fall out from the atmosphere.

    A more term is acid deposition, has two parts: Wet and Dry.

    Wet deposition refers to Acidic Rain, Fog and Snow, and

    Dry deposition refers to acidic gases and particles.

    About half of the acidity in the atmosphere falls back to the earth by means of Dry Deposition.

    CHEMISTRY OF ACID RAIN:

    Major contributing gases for acid rain are: Oxides of Sulfur (SOX), Oxides of Nitrogen

    (NOX), Oxides of Carbon (COX), and Chlorine (Cl2) dissolve in the air and causes acid rain.

    The following reactions show the acid formation due to these gases: as;

    Oxides of Sulfur reacts with water in air and forms Sulfuric Acid (H2SO4).

    SO2 + 2H2O H2SO4

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    Oxides of Nitrogen reacts with water in air and forms Nitric Acid (HNO3).

    NO2 + H2O HNO3

    Oxides of Carbon reacts with water in air and forms Carbonic Acid (HCO3).

    CO2 + H2O HCO3

    Chlorine reacts with water in air and forms Hydrochloric Acid (HCl)

    2Cl2 + 2H2O 4HCl + O2

    CAUSES OF ACID RAINS:

    Acid rain is caused by smoke and gases that are given off by factories and cars that run on

    fossil fuels. When these fuels are burned to produce energy, the sulfur that is present in the fuel

    combines with oxygen and becomes sulfur dioxide; some of the nitrogen in the air becomes

    nitrogen oxide. These pollutants go into the atmosphere, and become acid.

    Sulfur dioxide and nitrogen oxide are produced especially when coal is burnt for fuel and

    for more electricity, more coal is burnt. Burning coal produces electricity. Now-a-days people

    probably couldn't live without electricity, so coal will continue to be burnt; but electricity and

    energy are constantly being overused. Think of it this way: every time you turn on a light switch or

    the television set without really needing to, you're indirectly contributing to the acid rain problem.

    Of course, Automobiles produce nitrogen oxides (which cause acid rain), so every time you

    don't carpool when you can, you are helping to cause acid rain. So now that we know what causes

    acid rain, here's a look at how acid rain can hurt you and the world around you. . .

    EFFECTS OF ACID RAIN:

    Acid Rain can cause some serious problems: Among these are:

    The acidification of Lakes and Streams,

    Forest Damages,

    Decay of Buildings and Paints over them,

    Reduction in Visibility,

    An increase in Public Health Problems.

    EFFECTS ON HUMAN HEALTH:

    High level of Oxides of Sulfur in the air cause various types Lungs disorders, which

    affect some peoples ability to Breathe and increase both the disease and mortality

    rates in sensitive population, such as young children and the elderly.

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    Acids dissolve the Lead and Copper in water supply pipes, so if these dissolved

    metals enters in our drinking water, it becomes contaminated.

    Toxic (poisonous) metals such as Mercury and Cadmium which have been

    leached from the soil by acids can accumulate in lakes, streams, and reservoirs that are

    used for human consumptions. Consumption of Mercury can affect the Nervous system

    functioning.

    HOW ACID RAIN CAN BE PREVENTED:

    1. The best approach rain is to reduce the amount of NOX and SOX being released in the

    atmosphere.

    2. By fitting a catalytic converter to car can reduce the emission of NOX by up to 90%.

    3. If a fuel with low Sulfur content (oil) is burnt can reduce the formation of SOX.

    4. SO2 created during any combustion, can be absorbed if an appropriate chemical (like

    limestone) is present as a fuel burn. Now once the fuel is burnt, SO2 can be removed from

    the exhaust gases.

    5. Most of the systems spray a mixture of Limestone & Water onto the gases reacts with

    SO2 to form Gypsum.

    6. The best way to reduce the effect of acid rain not uses much energy in one place. As we can

    help in lot of ways: as;

    a. Turns off lights when we leave a room

    b. If we have a car then doesnt use it for the short journeys, etc. etc.

    EFFECTS OF ACID RAIN ON ENVIRONMENT

    Acid rain is an extremely destructive form of pollution, and the environment suffers from its

    effects. Forests, trees, lakes, animals, and plants suffer from acid rain.

    Trees are an extremely important natural resource. They provide timber, regulate local climate, and

    forests are homes to wildlife. Acid rain can make trees lose their leaves or needles, as is shown in

    these pictures of forests damaged by acid rain in Germany. The needles and leaves of the trees turn

    brown and fall off. Trees can also suffer from stunted growth; and have damaged bark and leaves,

    which makes them vulnerable to weather, disease, and insects. All of this happens partly because of

    direct contact between trees and acid rain, but it also happens when trees absorb soil that has come

    into contact with acid rain. The soil poisons the tree with toxic substances that the rain has

    deposited into it.

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    Lakes are also damaged by acid rain. A lake polluted by acid rain will support only the hardiest

    species. Fish die off, and that removes the main source of food for birds. Also, birds can die from

    eating "toxic" fish and insects. Just as birds can be killed from eating toxic fish, fish can die from

    eating animals that are toxic. Acid rain can even kill fish before they are born. Acid rain hits the

    lakes mostly in the springtime, when fish lay their eggs. The eggs come into contact with the acid,

    and the entire generation can be killed. Fish usually die only when the acid level of a lake is high;

    when the acid level is lower, they can become sick, suffer stunted growth, or lose their ability to

    reproduce.

    EFFECTS OF ACID RAIN ON ARCHITECTURE

    Architecture and artwork can be destroyed by acid rain. Acid particles can land on

    buildings, causing corrosion. When sulfur pollutants fall of the surfaces of buildings (especially

    those made out of sandstone or limestone), they react with the minerals in the stone to form a

    powdery substance that can be washed away by rain. This powdery substance is called gypsum.

    Acid rain can damage buildings, stained glass, railroad lines, airplanes, cars, steel bridges, and

    underground pipes.

    EFFECTS OF ACID RAIN ON HUMAN HEALTH

    Humans can become seriously ill, and can even die from the effects of acid rain. One of the

    major problems that acid rain can cause in a human being is respiratory problems. Many can find it

    difficult to breathe, especially people who have asthma. Asthma, along with dry coughs, headaches,

    and throat irritations can be caused by the sulfur dioxides and nitrogen oxides from acid rain.

    Acid rain can be absorbed by both plants (through soil and/or direct contact) and animals (from

    things they eat and/or direct contact). When humans eat these plants or animals, the toxins inside of

    their meals can affect them. Brain damage, kidney problems, and Alzheimer's disease have been

    linked to people eating "toxic" animals/ plants.

    When the United States Congress Office of Technology Assessment looked at the effects of acid

    rain in North America in the year 1982, they discovered that sulfur pollution kills 51,000 people in

    a year, and about 200,000 people become ill as a result of the pollution. People are getting sick and

    dying, but we can stop it! Go back to the main page to discover solutions to the acid rain problem.

    SOLUTIONS TO THE ACID RAIN PROBLEM

    Acid rain is a big problem, but it is not unstoppable. If the amount of sulfur dioxides and

    nitrogen oxides in the air is reduced, then acid rain will be reduced. There are many helpful things

    that "normal" people (people who aren't part of a power company or the government) can do. First

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    of all, conserve energy and pollute less! Use less electricity; and carpool, use public

    transportation, or walk when you can. This will help more than one might think. When less energy

    is used, less coal is burnt, and as a result, there is less acid rain. Experts say that if energy was used

    more carefully, we could cut the amount of fuel burned in half! Also, if coal was cleaned before it

    was burnt; the dangerous pollutants that cause acid rain would be cleaned away. If coal is crushed

    and washed in water, the sulfur washes out. However, this is a very costly method, and many power

    companies and governments do not want to spend their money cleaning coal. It is also costly to

    burn low-sulfur coal (low-sulfur coal gives off less sulfur in the air as opposed to high-sulfur coal).

    ATMOSPHERIC DISPERSION: (THE MODEL)

    A dispersion model is a mathematical description of the meteorological transport and

    dispersion process that is quantified in term of source and meteorological parameters during a

    particular time. The meteorological parameters required for use of the models include wind

    direction, wind speed, and atmospheric stability. In some models, provisions may be made of

    including lapse rate and vertical mixing height; most models will require data about the physical

    stack height, the diameter of the stack at the emission discharge point the exit gas temperature and

    velocity, and the mass rater of emission of pollutants.

    Models are usually classified as either short term of climatologically models. Short term

    models are generally used under the following circumstances (1) to estimate ambient

    concentrations where it is impractical to sample, such as over rivers or lacks, or at great distance s

    above the ground; (2) to estimate the required emergency source reductions associated with periods

    or air stagnations under air pollution episode alert condition; and (3) to estimate the most probable

    location of high, short term, ground level concentrations as part of a site selection evaluation for the

    location of air monitoring equipment. The model:- it gives the ground level concentration (x) of

    pollutant at a point (coordinates x and y) downwind from a stack with an effective height (H). The

    standard deviation of the plume in the horizontal and vertical directions is designated by sy and sz,

    respectively. The standard deviations are functions of the downward distance from the source and

    the stability of the atmosphere. The equation is as follows:

    Q

    X = e[- (Y/Sy)] . e [- (H/Sz)] Sy Sz u

    Where

    S(x, y, O, H) = downwind concentration at ground level, g/m3

    Q= emission rate of pollutants, g/s

    Sy, Sz = plume standard deviations, m

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    U = wind speed m/s

    The dispersion models require the input of data which includes:

    Meteorological conditions such as wind speed and direction, the amount of atmospheric

    turbulence (as characterized by what is called the "stability class"), the ambient air

    temperature and the height to the bottom of any inversion aloft that may be present.

    Emissions parameters such as source location and height, source vent stack diameter and

    exit velocity, exit temperature and mass flow rate.

    Terrain elevations at the source location and at the receptor location.

    The location, height and width of any obstructions (such as buildings or other structures) in

    the path of the emitted gaseous plume.

    Many of the modern, advanced dispersion modeling programs include a pre-processor module

    for the input of meteorological and other data, and many also include a post-processor module for

    graphing the output data and/or plotting the area impacted by the air pollutants on maps.

    The atmospheric dispersion models are also known as atmospheric diffusion models, air

    dispersion models, air quality models, and air pollution dispersion models.

    GAUSSIAN AIR POLLUTANT DISPERSION EQUATION:

    The technical literature on air pollution dispersion is quite extensive and dates back to the

    1930's and earlier. One of the early air pollutant plume dispersion equations was derived by

    Bosanquet and Pearson.[1]

    Their equation did not assume Gaussian distribution nor did it include

    the effect of ground reflection of the pollutant plume.

    Sir Graham Sutton derived an air pollutant plume dispersion equation in 1947 which did

    include the assumption of Gaussian distribution for the vertical and crosswind dispersion of the

    plume and also included the effect of ground reflection of the plume.

    Under the stimulus provided by the advent of stringent environmental control regulations,

    there was an immense growth in the use of air pollutant plume dispersion calculations between the

    late 1960s and today. A great many computer programs for calculating the dispersion of air

    pollutant emissions were developed during that period of time and they were called "air dispersion

    models". The basis for most of those models was the Complete Equation for Gaussian Dispersion

    Modeling Of Continuous, Buoyant Air Pollution Plumes shown below:

    where:

    f = crosswind dispersion parameter

    =

    g = vertical dispersion parameter =

    g1 = vertical dispersion with no reflections

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    =

    g2 = vertical dispersion for reflection from the ground

    =

    g3 = vertical dispersion for reflection from an inversion aloft

    =

    C = concentration of emissions, in g/m, at any receptor located:

    x meters downwind from the emission source point

    y meters crosswind from the emission plume centerline

    z meters above ground level

    Q = source pollutant emission rate, in g/s

    u = horizontal wind velocity along the plume centerline, m/s

    H = height of emission plume centerline above ground level, in m

    z = vertical standard deviation of the emission distribution, in m

    y = horizontal standard deviation of the emission distribution, in m

    L = height from ground level to bottom of the inversion aloft, in m

    exp = the exponential function

    The above equation not only includes upward reflection from the ground, it also includes

    downward reflection from the bottom of any inversion lid present in the atmosphere.

    The sum of the four exponential terms in g3 converges to a final value quite rapidly. For

    most cases, the summation of the series with m = 1, m = 2 and m = 3 will provide an adequate

    solution.

    It should be noted that z and y are functions of the atmospheric stability class (i.e., a measure of the turbulence in the ambient atmosphere) and of the downwind distance to the

    receptor. The two most important variables affecting the degree of pollutant emission dispersion

    obtained are the height of the emission source point and the degree of atmospheric turbulence. The

    more turbulence, the better the degree of dispersion.

    The resulting calculations for air pollutant concentrations are often expressed as an air

    pollutant concentration contour map in order to show the spatial variation in contaminant levels

    over a wide area under study. In this way the contour lines can overlay sensitive receptor locations

    and reveal the spatial relationship of air pollutants to areas of interest.

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    THE BRIGGS PLUME RISE EQUATIONS:

    The Gaussian air pollutant dispersion equation (discussed above) requires the input of H

    which is the pollutant plume's centerline height above ground leveland H is the sum of Hs (the actual physical height of the pollutant plume's emission source point) plus H (the plume rise due the plume's buoyancy).

    To determine H, many if not most of the air dispersion models developed and used between the late 1960s and the early 2000s used what are known as "the Briggs equations." G.A.

    Briggs published his first plume rise model observations and comparisons in 1965. In 1968, at a

    symposium sponsored by CONCAWE (a Dutch organization), he compared many of the plume rise

    models then available in the literature. In that same year, Briggs also wrote the section of the

    publication edited by Slade dealing with the comparative analyses of plume rise models. That was

    followed in 1969 by his classical critical review of the entire plume rise literature, in which he

    proposed a set of plume rise equations which have became widely known as "the Briggs

    equations". Subsequently, Briggs modified his 1969 plume rise equations in 1971 and in 1972.

    Briggs divided air pollution plumes into these four general categories:

    Cold jet plumes in calm ambient air conditions

    Cold jet plumes in windy ambient air conditions

    Hot, buoyant plumes in calm ambient air conditions

    Hot, buoyant plumes in windy ambient air conditions

    Briggs considered the trajectory of cold jet plumes to be dominated by their initial velocity

    momentum, and the trajectory of hot, buoyant plumes to be dominated by their buoyant momentum

    to the extent that their initial velocity momentum was relatively unimportant. Although Briggs

    proposed plume rise equations for each of the above plume categories, it is important to emphasize

    that "the Briggs equations" which become widely used are those that he proposed for bent-over, hot

    buoyant plumes.

    In general, Briggs's equations for bent-over, hot buoyant plumes are based on observations and

    data involving plumes from typical combustion sources such as the flue gas stacks from steam-

    generating boilers burning fossil fuels in large power plants. Therefore the stack exit velocities

    were probably in the range of 20 to 100 ft/s (6 to 30 m/s) with exit temperatures ranging from 250

    to 500 F (120 to 260 C).

    A logic diagram for using the Briggs equations [3]

    to obtain the plume rise trajectory of bent-over

    buoyant plumes is presented below:

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    SCRUBBERS

    The Scrubber is one of the most common pollution control device used by industries. It

    operates on a very simple principle that a polluted gas is brought into contact with the absorbent so

    that the pollutants can be removed.

    There are two types of Scrubbers: Wet Scrubbers and Dry Scrubbers. Mechanism of

    both the scrubbers is almost same. The only difference is in case of Dry Scrubbers End Product is

    in solid form while in case of Wet Scrubbers it is found in liquid form.

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    A) DRY SCRUBBERS:

    Dry Scrubbing system removes particulate matter and acid gases from combustion flue gas.

    While capturing mercury, heavy metals, dioxins and furans.

    The heart of the Dry Scrubbing process is the Spray Drier Absorber. Flue gas enters the

    top of the reactor where it is immediately mixed with a finely atomized spray of reagent. The

    reagent to form neutralized salt absorbs the acid gases; at the same time evaporates leaving a dry

    powder.

    The dried reaction products and fly ash are swept out of the reactor to a particulate collector

    where they are removed from the flue gas.

    The below chart shows that the application has the contaminants and the absorbents use for

    the absorption purpose.

    Typical Typical

    Application Contaminates Absorbents

    Aluminum Anode Baking Fluorides, SO2, VOCs Petroleum coke, Alumni

    Aluminum pot lines Benzene pyrene, Fluorides Petroleum coke, Alumni

    SO2

    Municipal Waste HF, Heavy Metals Ca (OH)2 + activated

    Carbon

    Clinical Waste HCl, SO2 NaCHO2 + activated

    Carbons

    Steel Production SO2 Ca (OH)2

    Cerium Production HCL, HF Ca (OH)2

    Molybdenum alloy

    Production HCL, HF Ca (OH)2

    B) WET SCRUBBERS:

    It absorbs both physical and chemical pollutants from the gas stream. This system relies on

    a chemical reaction with an absorbent to remove a wide range of pollutants including SO2, acid gas

    and other toxic from the flue gas. Here liquid absorbent is sprayed on the flue gas in an absorber

    vessel may dissolve or diffuse with liquid.

    In this process we have slurry of waste or by product is in liquid shape. This may require an

    additional treatment.

    Wet Scrubber technology can be applied to difficult processes such as gas absorption and

    particle collection, treating combustible particles and removal of wet, sticky or corrosive particles.

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    The mechanism of wet scrubbers is so simple that for better understanding of its function

    we can built our own Wet Scrubber: as;

    Procedure:

    1. Set up the apparatus as per process and put a paper towel in 55-ml flask and place this

    above the burner.

    2. Connect a 30-cm piece of rubber tubing in order to link first flask with the second, making

    sure an air-tight seal exists.

    3. Fill a second 500-ml flask approximately full of water. Construct a 3rd flask like 2nd.

    4. Connect rubber tubing and heat the 1st flask until smoke appears.

    5. Put a vacuum on the 3rd flask to draw a stream of smoke through the 2nd flask. If smoke

    collects in the 2nd

    flask above the water, a 2nd

    scrubber can be added

    6. Observe the change of color in the wet scrubber.

    ELECTROSTATIC PRECIPITATOR:

    A precipitator is a device that captures particulate from a gas stream. In the simplest term, a

    precipitator is a large box. The particulate laden gases are drawn into one side of the box using

    perforated plate and diffusers to evenly distribute the gas. Inside high voltage electrodes impart a

    negative charge to the particles entrained in the gas. These negatively charged particles leave the

    box up to 99% cleaner than when it entered.

    In Dry ESP the particles are usually removed from the collecting plate by introducing a jerk

    in it. In a Wet ESP the collecting plate is emptied/ flushed by pumping water in it.

    Dry units are attractive due to their ability to collect and transport the dust in a dry

    condition. This eliminates the use of water and the concerns of pollution, corrosion and dewatering.

    If the dust particles can be collected and handled in a dry condition it is always more advantageous

    to employ a dry electro precipitator.

    The electrostatic precipitator uses a voltage differential between two electrodes to extract

    and collect particulate.

    Where Electrostatic Precipitators are utilized??

    Electrostatic Precipitators are not only used in utility applications but also in other industries

    such as cement (dust), pulp and paper (salt cake and lime dust), petro-chemicals (sulfuric acid mist)

    and steel (dust and fumes).

    APPLICATIONS:

    INDUSTRY MATERIAL COLLECTED

    Coal-fired Power Generation Fly ash

  • 19 Pulp and Paper Salt cake, lime dust

    Chemical Sulfuric acid Mist

    Cement Dust

    Steel Dust, Fumes

    Electrostatic Precipitators has been reliable technology since early 1900s. Originally

    developed to abate serious smoke nuisance, the manufacturers of Zinc, Copper and Lead quickly

    found electric gas cleaning a cost efficient way to recover valuable product carried out of the stack

    from furnace operation. Today Electrostatic Precipitators are found mainly on lower plants,

    incinerators, and various boiler applications.

    In the wood products industry, the dry electrostatic precipitator preceded by multi clones is now

    normally considered the best available control technology for wood fired boiler emissions.

    Wet electrostatic precipitators have found renewed interest from particleboard, and plywood veneer

    manufactures for controlling dryer exhaust.

    A dry ESP operates at temperature above 7000F and maintains the fly ash in its natural dry

    condition simplifying material handling.

    CYCLONE:

    For particle size greater than above 10 um, the collector of choice is the cyclone. This is

    inertial collector with no moving parts.

    The particulate gas is accelerated through a spiral (round) Motion, which imparts a

    centrifugal force to the particles. Due to which the particles by force come out of the gas and

    impact on the cylinder wall of the cyclone. Then they slide to the bottom of the cone, where they

    are removed through an air tight valving system.

    The efficiency of collection of various particle sizes can be determined through an

    expression given below.

    [(9 B2 H)]

    d0.5=

    [p Qg ]

    As the diameter of the cyclone is reduced, the efficiency of collection increased, pressure

    drop also increases which ultimately increases the power requirement for moving the gas through

    the collector.

    With the increase in the efficiency tangential velocity remains constant and the efficiency

    increases with increase in the power consumption by using multiple cyclones in parallel.

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    GREENHOUSE EFFECT / GLOBAL WARMING:

    The Greenhouse Effect is a natural phenomenon that warms up the earth. It works on the

    same principles as the ordinary garden glasshouse, which allows the light to get in, but does

    not allow the heat to get out.

    The earth is surrounded by a shield of atmospheric gases primarily nitrogen (78%) and

    oxygen (21%). The remainder of the air composition is made up of what are called as trace

    gases, which include carbon dioxide (CO2), methane (CH4) etc.

    The earth maintains its temperature through insulation with a thermal blanket of

    greenhouse gases which allow penetration of the suns rays but prevent some heat radiation

    back into space. Light from the sun penetrates the atmosphere and reaches the earth surface,

    warming it up.

    The earth then radiates much of this heat in the form of infrared rays, which have a wave

    length longer than that of visible light, and are thus absorbed by the greenhouse gases. This

    absorption of heat warms up the atmosphere, which in turn radiates some of the heat back to

    earth.

    Greenhouse gases related to human actively are increasing at an unprecedented rate leading

    to an overall warming of the earths surface. The major greenhouse gases include carbon

    dioxide, tropospheric ozone, nitrous oxide, methane, CFCs and water vapor. These gases are

    largely transparent to solar radiation but opaque to outgoing long wave radiation .

    A brief discussion on greenhouse gases and their role is give below:

    Carbon Dioxide (CO2):

    Carbon dioxide is a by-product of most living things and many commercial processes.

    Carbon dioxide is a waste product when organism burn food (flue) to release energy

    required for life activities. CO2 is also given off when humans burn fossil fuels, and

    when a huge amount of fuel is used for transpiration and energy.

    Only about half the carbon dioxide emitted in the atmosphere is absorbed by oceans,

    forests, the rest remains in the atmosphere, acting as greenhouse gas. The overall

    contribution of manmade CO2 to enhance the greenhouse effect is thought to be of the

    order of 20%.

    Carbon dioxide differs from nitrogen (N2), and oxygen (O2), the two main gases in the

    atmosphere, in that it absorbs infra-red radiation (heat), causing the temperature of the

    earth to increase.

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    Methane (CH4):

    In general, methane is formed from the decomposition of organic material. The major

    sources of methane are livestock, waste decomposition such as in landfill areas, and coal

    mining. Methane is also released from natural gas leakages. Rice paddies, gas drilling,

    venting and transmission, natural marches and swamps, and burning vegetation.

    The increase in methane is linked to the worlds growing population and its need for

    food and disposable goods. Studies suggest that methane is about 20 times more

    powerful as a greenhouse gas than CO2.

    Chlorofluorocarbons (CFCs):

    The chlorofluorocarbons (CFCs) are part of a larger family of compounds known as the

    halocarbons of which those containing chlorine and bromine are of primary concern.

    CFCs are non reactive, non caustic, non corrosive and nonflammable chemicals mainly

    used in refrigeration, air conditioning, dry cleaning, plastic foams, and aerosols.

    CFCs are also a potent greenhouse gas. In the upper atmosphere, ultra violet light

    breaks off a chlorine atom from a CFCs molecule, which then reacts with ozone

    molecule breaking it apart, and forming an oxygen molecule, and chlorine monoxide.

    The free oxygen atom breaks up chlorine monoxide and chlorine is free again to repeat

    the process. As more and more of the ozone are depleted the ozone layer gets thinner,

    and allows more ultraviolet rays reach the surface of earth.

    Nitrous Oxide (N2O)

    This greenhouse gas is released by burning of fossil fuels and vegetation, and by the use

    of nitrogenous fertilizers in agriculture. One process which causes nitrous oxide to be

    released is denitrification by bacteria in soil, groundwater and the oceans.

    This process may occur in natural soils but can also be increased by planting pastures

    with nitrogen fixing plants cultivated to improve soil fertility. The addition of nitrate

    and ammonium fertilizers to soils is

    NOISE AS AN ENVIRONMENTAL POLLUTION:

    Noise pollution, usually called Environmental Noise Pollution in technical venues, is

    unwanted human-created sound that disrupts the environment. The dominant form of noise

    pollution is from transportation sources, principally motor vehicles. The word noise comes from the

    Latin word nausea meaning seasickness.

    Noise is unwanted sound barking dogs, loud music, passing traffic. Studies show that

    over 40 percent of Peoples are disturbed at home or lose sleep because of Noise Pollution.

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    Everyone reacts differently to noise. What can be unbearable for one person may pass

    almost unnoticed by another. How annoyed we become depends on the loudness, time, place and

    frequency of noise. Distinct features of noise, such as screeches or rumbles, are also important.

    Noise is measured on the decibel scale. Noise levels, referred to as decibels on the (A) scale

    (written as dB (A)) are a good indicator of peoples response to noise.

    Human-created noise harmful to health or welfare. Transportation vehicles are the worst

    offenders, with aircraft, railroad stock, trucks, buses, automobiles, and motorcycles all producing

    excessive noise. Construction equipment, e.g., jackhammers and bulldozers also produce

    substantial noise pollution.

    Noise intensity is measured in DECIBEL unit. The decibel scale is logarithmic; each 10-decibel increase represents a tenfold increase in noise intensity. Human perception of loudness also

    conforms to a logarithmic scale; a 10-decibel increase is perceived as roughly a doubling of

    loudness. Thus, 30 decibels is 10 times more intense than 20 decibels and sounds twice as loud; 40

    decibels is 100 times more intense than 20 and sounds 4 times as loud; 80 decibels is 1 million

    times more intense than 20 and sounds 64 times as loud. Distance diminishes the effective decibel

    level reaching the ear. Thus, moderate auto traffic at a distance of 100 ft (30 m) rates about 50

    decibels. To a driver with a car window open or a pedestrian on the sidewalk, the same traffic rates

    about 70 decibels; that is, it sounds 4 times louder. At a distance of 2,000 ft (600 m), the noise of a

    jet takeoff reaches about 110 decibelsapproximately the same as an automobile horn only 3 ft (1 m) away.

    Subjected to 45 decibels of noise, the average person cannot sleep. At 120 decibels the ear

    registers pain, but hearing damage begins at a much lower level, about 85 decibels. The duration of

    the exposure is also important. There is evidence that among young Americans hearing sensitivity

    is decreasing year by year because of exposure to noise, including excessively amplified music.

    Apart from hearing loss, such noise can cause lack of sleep, irritability, heartburn, indigestion,

    ulcers, high blood pressure, and possibly heart disease. One burst of noise, as from a passing truck,

    is known to alter endocrine, neurological, and cardiovascular functions in many individuals;

    prolonged or frequent exposure to such noise tends to make the physiological disturbances chronic.

    In addition, noise-induced stress creates severe tension in daily living and contributes to mental

    illness.

    Noise is recognized as a controllable pollutant that can yield to abatement technology. In the

    United States the Noise Control Act of 1972 empowered the Environmental Protection Agency to

    determine the limits of noise required to protect public health and welfare; to set noise emission

    standards for major sources of noise in the environment, including transportation equipment and

    facilities, construction equipment, and electrical machinery; and to recommend regulations for

    controlling aircraft noise and sonic booms. Also in the 1970s, the Occupational Safety and Health

    Administration began to try to reduce workplace noise. Funding for these efforts and similar local

    efforts was severely cut in the early 1980s, and enforcement became negligible.

    EFFECTS OF NOISE:

    The WHO suggests that noise can affect human health and well-being in a number of ways,

    including annoyance reaction, sleep disturbance, interference with communication, performance

    effects, effects on social behavior and hearing loss. Noise can cause annoyance and frustration as a

    result of interference, interruption and distraction. Activity disturbance is regarded as an important

  • 23

    indicator of the community impact of noise The AEC national noise survey assessed two major

    disturbances, for example, to listening activities and sleep: 41% of respondents reported

    experiencing disturbance to listening activities and 42% to sleep.

    Research into the effects of noise on human health indicates a variety of health effects.

    People experiencing high noise levels (especially around airports or along road/rail corridors) differ

    from those with less noise expo sure in terms of: increased number of headaches, greater

    susceptibility to minor accidents, increased reliance on sedatives and sleeping pills, increased

    mental hospital admission rates.

    Exposure to noise is also associated with a range of possible physical effects including:

    colds, changes in blood pressure, other cardiovascular changes, increased general medical practice

    attendance, problems with the digestive system and general fatigue.

    There is fairly consistent evidence that prolonged exposure to noise levels at or above 80

    dBcan cause deafness. The amount of deafness depends upon the degree of exposure.

    EFFECTS OF NOISE POLLUTION ON:

    (A)- HUMAN HEALTH:

    Hearing

    The mechanism for chronic exposure to noise leading to hearing loss is well established.

    The elevated sound levels cause trauma to the cochlear structure in the inner ear, which gives rise

    to irreversible hearing loss. The pinna (visible portion of the human ear) combined with the middle

    ear amplifies sound levels by a factor of 20 when sound reaches the inner ear. In Rosen's seminal

    work on serious health effects regarding hearing loss and coronary artery disease, one of his

    findings derived from tracking Maaban tribesmen, who were insignificantly exposed to

    transportation or industrial noise. This population was systematically compared by cohort group to

    a typical U.S. population. The findings proved that aging is an almost insignificant cause of hearing

    loss, which instead is associated with chronic exposure to moderately high levels of environmental

    noise.

    Noise effects on both health and behavioral in nature. The following discussion refers to

    sound levels that are present within 30 to 150 meters from a moderately busy highway.

    Cardiovascular Health

    High noise levels can contribute to Cardiovascular effects and exposure to moderately high

    (e.g. above 70 dB) during a single eight hour period causes a statistical rise in blood pressure of

    five to ten mmHg; a clear and measurable increase in stress [1]

    ; and vasoconstriction leading to the

    increased blood pressure noted above as well as to increased incidence of coronary artery disease.

    (B)- ENVIRONMENT:

    Noise pollution can also be harmful to animals. High noise levels may interfere with the

    natural cycles of animals, including feeding behavior, breeding rituals and migration paths. The

    most significant impact of noise to animal life is the systematic reduction of usable habitat, which

    in the case of endangered species may be an important part of the path to extinction. Perhaps the

    most sensational damage caused by noise pollution is the death of certain species of beaked whales,

    brought on by the extremely loud (up to 200 decibels) sound of military sonar.

  • 24

    SAFE LEVELS OF NOISE

    State government regulations state that our maximum daily noise dose should be no more

    than the equivalent of 85dB(A) for eight hours a day. Permanent hearing damage is likely to occur

    if this daily dose is exceeded repeatedly.

    PROBLEMS CAUSED BY NOISE

    Annoyance

    When we think, talk, relax, listen to music or sleep we need quiet. Even relatively low

    levels of noise can cause annoyance and frustration. Sudden increases in volume and tone makes

    sounds annoying the reason why sirens are so penetrating. A quieter background can make noise more intrusive. Natural sounds are generally less annoying than ones we think unnecessary or

    controllable. Intermittent sounds such as a tap dripping on a quiet night can be more disturbing than

    the sound of falling rain.

    Speech interference

    Noise can interfere with speech. When the background noise level is 50dB(A), normal conversation

    can be easily carried with someone up to 1m away. Any more than that and problems will arise.

    Sleep interference

    Noise can wake people from sleep and keep them awake. Even if not actually woken, a persons sleep pattern can be disturbed, resulting in a reduced feeling of well-being the next day.

    Decreased work performance

    As noise levels increase, our ability to concentrate and work efficiently and accurately reduces.

    Louder noise bursts can be more disruptive. Noise is more likely to reduce the accuracy of the work

    than reduce the total quantity of work done. Complex tasks are more likely to be impaired. Noise

    can also make instructions or warnings unclear, resulting in accidents.

    Hearing loss

    Prolonged exposure to noise levels above 85dB can damage inner ear cells and lead to hearing loss.

    At first, hearing loss is usually temporary and recovery takes place over a few days. After further

    exposure, a person may not fully recover their initial level of hearing irreversible damage will have been done, causing deafness. The extent of deafness depends on the degree of exposure and

    individual susceptibility. Even brief exposure to very high levels of 130dBor more can cause

    instant, irreversible hearing damage.

    MAJOR SOURCES OF NOISE:

    The overarching cause of most noise worldwide is generated by transportation systems,

    principally motor vehicle noise, but also including aircraft noise and rail noise. Hybrid vehicles for

    road use are the first widely sold automobiles in 100 years to achieve significant noise source

    reduction. Poor urban planning may also give rise to noise pollution, since juxtaposition of

    industrial to residential land uses, for example, often results in adverse consequences for the

    residential acoustic environment.

    Besides transportation noise, other prominent sources are office equipment, factory

    machinery, appliances, power tools, lighting hum and audio entertainment systems. With the

    popularity of digital audio player devices, individuals in a noisy area might increase the volume in

    order to drown out ambient sounds. Construction equipment also produces noise pollution.

  • 25

    Noise from recreational off-highway vehicles (OHVs) is becoming a serious problem in

    rural areas. ATVs, also known as quads or four wheelers, have increased in popularity and are

    joining the traditional two wheeled dirt motorcycles for off-road riding.

    The noise from ATV machines is quite different from that of the traditional dirt bike. The

    ATVs have large bore, four stroke engines that produce a loud throaty growl that will carry further

    due to the lower frequencies involved. The traditional two stroke engines on dirt bikes have gotten

    larger and, while they have higher frequencies, they still can propagate the sound for a mile or

    more. The noise produced by these vehicle is particularly disturbing due to the wide variations in

    frequency and volume.

    Recreational off-road vehicles are generally not required to be registered and the control of

    the noise they emit is absent in most communities. However, there is a growing awareness that

    operation of these machines can seriously degrade the quality of life of those within earshot of the

    noise and some communities have enacted regulations, either by imposing limits on the sound or

    through land use laws. Rider organizations are also beginning to recognize the problem and are

    enlightening members as to future restrictions on riding if noise is not curtailed.

    MAJOR NOISE SOURCES ARE:

    Road Traffic

    Road traffic noise is one of the most widespread and growing environmental problems in urban

    NSW. In 1991 it was estimated that in Sydney:

    1.5 million residents were exposed to outdoor traffic noise levels defined by the OECD as

    undesirable (between 55 and 65 dB(A)), where sleep and amenity are affected

    350,000 of these residents were estimated to experience noise levels considered as

    unacceptable (greater than 65dB), where behavior patterns are constrained and health

    effects are demonstrable.

    In 1994 the NSW Road Traffic Noise Taskforce reported that road traffic noise has become a

    major urban environmental problem because:

    historically, land use planning has not been well integrated with transport planning,

    allowing residential developments and major transport corridors to occur in close proximity

    without appropriate buffer zones or treatment to buildings

    there has been an increasing community reliance on road transportation, and a reluctance to

    implement or accept partial solutions involving greater use of public transport traffic on

    many existing roads through built-up areas has increased well beyond expectations

    prevailing during planning or construction of the roadways

    potential solutions, apart from new vehicle noise standards are complex, often costly, and

    require coordinated actions by a number of agencies and the community

    while there is high community awareness of the problem, there is a general lack of

    understanding of its extent and possible solutions.

    The impact of road traffic noise on the community depends on various factors such as road

    location and design, land use planning measures, building design, vehicle standards and driver

    behavior.

    Motor vehicle ownership in NSW has increased substantially over the last 30 years; and general

    levels of road traffic noise throughout NSW have increased through this period.

  • 26

    Although some site specific measurements have been taken in response to particular issues,

    there is a general lack of consistent data on the impact of road traffic on noise levels within the state

    and even within urban areas. The lack of background noise data collected both before and after

    construction of new roads or expansion of existing ones, making it difficult to assess the impact on

    ambient noise levels. In response to this lack of data, the RTA is developing a comprehensive road

    traffic noise database of all its road traffic noise measurements. RTA information indicates that

    many of the major roads within Sydney have traffic volumes in excess of 30,000 vehicles per day.

    This volume of traffic produces a noise level of about 70 dB.

    Air Traffic

    In the Sydney metropolitan area it has been the cause of considerable community concern,

    particularly since the opening of the third runway at Sydney's Kingsford Smith airport and with the

    planning of a second Sydney airport. The extent of aircraft noise impact depends on the types of

    aircraft flown, the number of flights and flight paths.

    Between 1990 and 1996 total aircraft movements at Sydney airport increased by 37% to

    meet the increasing demand at the airport . The in crease in the number of flights, an important

    factor in overall noise levels, has led to an increase in general noise levels associated with air

    traffic. The third runway at Sydney airport was opened by the Commonwealth government in

    November 1994. Airport operations changed to accommodate the new runway and included the

    introduction of new flight paths. The change in operations at Sydney airport led to changes in the

    noise levels experienced by the community. Many affected areas reported that they were being

    exposed to higher noise impacts than predicted in the environmental impact statement or that

    impacts were occurring in areas where no aircraft noise was predicted. Recent changes to the

    operation of Sydney airport have led to an increase in the level of complaints.

    Rail Traffic

    There are two main sources of noise and vibration relating to the operation of the rail

    network: the operation of trains and the maintenance and construction of rail infrastructure.

    The level of noise associated with rail traffic is related to the type of engine or rolling stock

    used, the speed of the train and track type and condition. Major NSW population centers are served

    by electric trains which are generally quieter than diesel. Areas affected by freight trains often

    experience higher noise levels than areas affected by passenger trains. The problem of noise is

    compounded by the requirements of railway operations (especially night operations) and factors

    such as stopping patterns and topography which can lead to localized problems.

    Rail noise can be considerable, but generally affects a far smaller group of the population

    than road or aircraft noise as it is generally confined to residents living along rail lines in urban

    areas. While changes to locomotives and rolling stock mean that they have become quieter over the

    last few years, railway noise remains a problem because of longer, more frequent and faster trains

    and the build up of the urban environment.

    The Hunter Valley is the most important centre for coal production for export purposes in

    NSW. Large coal trains used to carry the coal are a source of noise related complaints in the area.

    In response to this Freight Rail Corp organized an extensive study of rail related noise. The study

    found that the majority of the sites monitored along the Sydney to Newcastle line and along major

    coal routes, on occasions, exceeded at least one of the EPA targets for environmental noise of

    railway operation. For residents adjacent to existing railway lines the target levels are the maximum

    level of 85 dB and level of 60 dB(A). Although noise associated with freight trains is generally

  • 27

    higher than that from passenger trains, the study also indicated that passenger traffic was a

    significant component of overall noise along the Sydney-Newcastle line. Freight Rail Corp and Rail

    Access Corp are currently compiling a profile of noise associated with all freight and passenger

    trains in NSW.

    Neighborhood & Domestic Noise

    Other significant sources of noise annoyance in Sydney include barking dogs, car alarms, garbage

    recycling, lawn-mowers, building construction and household noise. A significant proportion of

    complaints received by local councils, the police and the EPA are related to neighborhood noise

    (EPA 1993a). The national noise survey found that noise from barking dogs and road traffic have

    the greatest impact on residential communities. Noise from barking dogs is of particular concern

    because it is unpredictable and often happens repeatedly.

    Incompatible land use

    Generally the determination of land use zoning includes the separation of activities which are

    incompatible due to noise levels. For example, heavy industrial area will be separated from

    residential areas by light industrial, recreational facilitates and/or retail activities. However,

    changing land uses over many decades and earlier inappropriate zoning controls have resulted in

    unacceptable noise levels for some areas and uses.

    The Department of Urban Affairs and Planning (DUAP) has developed environmental impact

    statement guidelines for major developments which address sitting issues, for which noise

    generation is a consideration, in addition to ensuring noise impact assessment is carried out as part

    of the assessment process.

    To address land use planning along rail corridors, the rail sector has developed a strategy to

    encourage inclusion of noise and vibration generated by existing and future rail operations in the

    development process. A key aim of the strategy is to improve awareness of council planners,

    developers and the community to rail noise and vibration related issues. As part of this initiative in

    December 1995 the rail sector distributed a series of educational guidelines to all councils with rail

    lines in their area. This was followed in March 1996 by an educational workshop for councils.

    Increased awareness of the issue of incompatible land use planning has led to a number of councils,

    including Hornsby, Sydney City, Botany, Fairfield and Sutherland in Sydney, introducing codes for

    noise in development plans.

    NOISE CONTROL MEASURES

    The EPA controls noise from scheduled premises those required by the Noise Control Act

    to have a license and noise associated with rail traffic and the construction or upgrading of

    freeways and toll roads. The Police and local councils are generally responsible for neighborhood

    noise issues and have authority to issue noise abatement directions to control noise from premises

    and for noise from burglar alarms. Local councils have an essential role in minimizing the effects of

    excessive noise, particularly in their local residential areas, from smaller factories, non-scheduled

    premises and public places. The Waterways Authority has specific responsibilities in relation to

    noise from vessels in navigable waters.

    Air services Australia is responsible for control of environmental noise associated with

    aircraft arriving and departing from Sydney (Kingsford Smith) airport. The Federal Airports

    Corporation, as the airport owner and operator is responsible for noise associated with noise at the

    airport including on-ground air movements.

  • 28

    The Environmental Planning and Assessment Act 1979 provides responsibility and

    opportunity for controlling environmental noise through the planning process. Consideration of the

    implications of environmental noise at the planning stage can often avoid or minimize the need for

    supplementary noise controls. However, in some instances noise reduction or mitigation measures

    are essential, for example:

    controls on noise levels generated from a source (e.g. vehicle/machine design,

    driver/operator behavior)

    controls on noise transmission (e.g. through the use of noise barriers)

    measures to reduce the level of sound reaching a receiver (e.g. soundproofing sensitive or

    affected buildings).

    Major Noise Control Measures are:

    Reducing Road Traffic Noise

    The Noise Control (Motor Vehicles and Motor Vehicle Accessories) Regulation 1995

    prescribes noise levels for classes of motor vehicles and restricts allowable noise levels for vehicles

    manufactured at variable times depending on the class of the vehicle. In addition, the EPA conducts

    a noisy vehicle testing program on passenger cars, motor bikes and trucks. However, despite

    progress in addressing the problem of individually noisy vehicles, the rise in traffic volume has

    meant an increase in traffic noise overall.

    The Road Traffic Noise Committee was formed in December 1995 to facilitate the

    implementation of the recommendations made by the Road Traffic Noise Taskforce. Initiatives

    completed or currently under way as part of this process include:

    developing the EPA environmental criteria for road traffic noise (see below)

    releasing the Roads and Traffic Authority's (RTA) community education information about

    traffic noise and homes

    in 1996, 250 RTA Vehicle Inspectors were trained by the EPA in measuring and identifying

    noisy vehicles and were declared Authorized Officers under the Noise Control Regulations

    Researching road traffic noise for which the RTA has allocated $230,000 for 1996-97

    Promoting, at a national level, a new Australian Design Rule for heavy vehicle exhaust

    breaks (a joint effort by the EPA and the RTA).

    The EPA, in consultation with the RTA, is currently finalizing environmental noise criteria to

    indicate noise levels that will guide the development of strategies to protect people and

    communities from excessive levels of road traffic noise. The environmental criteria will improve

    the management of road traffic noise for new or upgraded roads, and will apply to: new roads,

    bridges or freeways; new road use or upgrading of an existing road, bridge or freeway; or new

    development near an existing road.

    In response to community concerns about noise from major arterial roads, the NSW

    Government introduced the Noise Abatement Program. A noise complaint register was developed

    by the RTA as a first step to implementing the program, which provides noise abatement measures

    to reduce noise in sensitive locations such as residences and schools. These include noise mounds,

    noise attenuation walls and quieter road surfacing. In 1995-96 a total of $8,223,000 was spent

    under the program benefiting at least 1,200 homes, 5 schools and 3 churches (information supplied

    to EPA by RTA). A further $14,720,000 has been allocated for 1996-97.

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    Some local council are addressing the issue of road traffic noise by introducing traffic

    management initiatives to reduce noise. These include use of traffic calming measures, resealing of

    council-controlled roads and blocking of streets to limit access to certain routes.

    At a federal level the National Road Transport Commission is developing a new Australian

    Design Rule to limit noise from exhaust brakes on new heavy vehicles. An education campaign to

    limit the use of exhaust brakes on current vehicles is also under preparation. Both of these are

    planned to be implemented in December 1997.

    Since traffic volumes and noise levels are connected, the continuing growth in traffic volume

    within many urban areas of NSW can only further increase the noise levels. Reducing reliance on

    private transport and utilizing public transport is a strategy which will reduce traffic volumes and

    noise. To reduce the impact of environmental ambient noise levels to the population in NSW it is

    important to consider transportation needs in an integrated fashion to reduce the impact to the

    community.

    Reducing Air Traffic Noise

    A range of measures have been introduced by the Commonwealth government to reduce or mitigate

    some of the noise impact associated with Sydney airport, including:

    a noise amelioration program that includes insulation and acquisition of the most affected

    properties, including houses, schools, child care centers, nursing homes and hospitals. As of

    31 January 1997, $64,326,000 had been spent on insulation (the average cost for a house is

    $38,000) and $31,900,000 on land acquisition (data supplied to EPA by Commonwealth

    Department of Transport & Regional Development 1997)

    the introduction of an aircraft noise levy in October 1995 for each jet aircraft landing at the

    airport. The level of the levy is based on the noise characteristics of the aircraft. Money

    from the levy is being used to pay for noise amelioration measures.

    The Commonwealth government, through Air services Australia, is now pursuing a policy of

    sharing the noise from aircraft using the airport. Further changes designed to continue the policy of

    sharing aircraft noise across Sydney have been proposed in a long term operating plan for the

    airport. In November/December 1996, there were 11,847 complaints associated with aircraft noise

    from Sydney airport (data from Air services Australia's Noise Inquiry Unit). This represents an

    increase of 241% compared to the same period in 1995.

    The issue of air traffic related noise is one of the major community concerns regarding the

    proposed second Sydney airport. An environmental impact statement for the proposal is currently

    being prepared.

    Reducing Rail Traffic Noise

    Under the provisions of the Noise Control Act 1975 in NSW the railway system is classified

    as scheduled premises and as such the EPA has a regulatory role, and seeks to achieve noise targets

    for rail operations throughout the state to minimize the impact on local residents.

    The railway sector has, in recent years, recorded an increase in the identification and reporting

    of noise problems by the community. There is a range of initiatives to address this issue, including:

    retrofitting existing locomotives to reduce noise emitted

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    upgrading existing track to continuously welded rail which removes rail joints-a

    significant source of noise and vibration

    designing new bridges to reduce noise and retrofitting of existing bridges with noise

    attenuation devises

    deploying quieter rolling stock in noise sensitive areas

    use of electric locomotives at night time wherever possible in the Sydney metropolitan area

    Altering the holding pattern of trains to avoid them being held at signals for extended

    periods in built up areas.

    OZONE DEPLETION

    Without ozone, every living thing on the earths surface would be incinerated. The presence

    of Ozone in the upper atmosphere (20 to 40 km and up) provides a barrier to ultraviolet (UV)

    radiation. Too much UV will cause skin cancer. Although oxygen also serves as a barrier to UV

    radiation, it only absorbs over a narrow band centered at wavelength of 0.2 m.

    Air Pollution threats to this protective ozone shield. It is assumed that Chlorofluorocarbons

    (CFC) that are used as aerosol propellants and refrigerants react with ozone. The frightening aspect

    of this series of reactions is that the chlorine atom removes ozone from the system. And that the

    chlorine atom is continually recycled to convert more ozone to oxygen. It has been estimated that a

    5% reduction in ozone could result in nearly a 10% increase in skin cancer. Thus CFCs in the lower

    atmosphere become a serious air pollution problem at higher elevations. By 1987, the evidence that

    CFCs destroy ozone in the stratosphere above Antarctica every spring had become irrefutable.

    More than half of the total ozone column was wiped out and essentially all ozone disappeared from

    some regions of the stratosphere.

    Research confirmed that the ozone layer, on a worldwide basis, shrunk approximately

    2.5% in the preceding decade. Initially, it was believed that this phenomenon was peculiar to the

    Geography and Climatology of Antarctica and that the warmer northern hemisphere was strongly

    protected from the processes that lead to massive ozone losses.

    A number of alternatives to the fully chlorinated, and, hence, more destructive CFCs have

    been developed. These are primarily fluorocarbons that carry hydrogen atoms, which make them

    more easily oxidized in the lower atmosphere before they reach stratosphere. These compounds are

    now undergoing toxicity testing before they can become commercially available.

    INDOOR AIR POLLUTION

    People who lived in cold climates may spend from 70 to 90% of their times indoors. In the

    last two decades, researchers have become interested in identifying sources, concentrations and

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    impacts of air pollutants that arise in conventional domestic residences. Starting results indicates

    that, in certain cases, indoor air may be substantially more polluted than the outdoor air.

    Carbon monoxide from improperly operating furnaces has long been a serious concern. In

    numerous instances people have died from furnace malfunction. Gas ranges, ovens, pilot lights, gas

    and kerosene space heaters and cigarette smoke all contribute in indoor pollution. The public has to

    expect that the recreational habits of smokers should not interfere with the quality of the others

    breathe. Smokers were allowed to smoke only in the designated lounge area.

    NO2 levels have been found to range from 70 g/m3 in an air-conditioned house with

    electric ranges to 182 g/m3 in non-air-conditioned houses with gas stoves. Formaldehyde (CH2O)

    and radon are not regulated as ambient air pollutants have been found in dwellings at alarmingly

    high concentrations.

    Unlike the other air pollution sources that continue to emit as long as there is anthropogenic

    activity CH2O is ventilated over a period of time the concentration will drop. In next few years we

    may anticipate some regulatory effort to reduce the emission of these pollutants. The house and

    apartment dwellers has little recourse other than to replace gas appliances, remove or cover

    formaldehyde sources, and put out the smokers.