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Air pollutionsources & effects

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Environmental Pollution

An undesirable change in the physical,chemical or biological characteristics ofenvironment

(Or)

Addition or excessive addition of certainmaterials to the physical environment

(Air, water, & lands), making it less fit orunfit for life

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Envelope of the earth

The atmosphere is the gaseous envelopethat surrounds the earth and constitutesthe transition between its surface and thevacuum of space.

The atmosphere is composed primarily ofnitrogen (N2) and oxygen (O2)

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Envelope of the earth

1.Thermosphere

2.Stratosphere

3.Mesosphere

4.Troposphere

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Troposphere

The first layer is called. People, plants,animals, and insects live in thetroposphere. It is the layer where allweather occurs

The troposphere begins at ground leveland extends 12km (7.5 miles) up into thesky where it meets with the second layercalled the stratosphere

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Stratosphere

The stratosphere begins at the 12km (7.5 mile)point and reaches 50km (21.1 miles) into the sky.

An important layer of atmosphere containingozone is located inside the stratosphere.

Ozone (O3) is a special form of oxygen, and theozone layer is very important to all life on earth.

Ozone blocks large amounts of solar ultraviolet

radiation from entering the troposphere.

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Mesosphere

The third layer is called the mesosphere.The mesosphere begins 50km (21.1miles)above the earth's surface.

Temperatures are warmest at the lowestlevel of the mesosphere and coldest at itshighest level.

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Thermosphere

The thermosphere begins 80km (49.7 miles) above theearth.

Temperatures in the thermosphere go up when movingfarther away from ground level due to the sun's energy.

The increase in temperature stops at this height, beyondwhich lies the exosphere. The exosphere is the highestlayer of the atmosphere.

The exosphere extends to 40,000 miles above theearth's surface.

The thermosphere and the exosphere together make upthe upper atmosphere.

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Giant safety blanket

The troposphere, stratosphere, mesosphere,

and thermosphere act together as a giant safetyblanket

They keep the temperature on the earth'ssurface from dipping to extreme icy cold that

would freeze everything solid, or from soaring toblazing heat that would burn up all life.

In the study of air pollution control the layers ofthe air that are most important are the

troposphere and the stratosphere

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Composition of air Air is a complex mixture made up of

many chemical components

The primary components of air arenitrogen (N2), oxygen (O2), andwater vapor (H2O)

About 99 percent of air is nitrogen(78%) and oxygen (21%)

The remaining percent includes trace

quantities of substances such ascarbon dioxide (CO2), methane(CH4), hydrogen (H2), argon (Ar) andhelium (He)

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Types of pollutants1.Primary pollutant :It is one that is emitted into theatmosphere directly from the

source of the pollutant andretains the same chemicalform

2.Secondary pollutant :It is one that is formed byatmospheric reactions ofprecursor or primary emissions

Secondary pollutantsundergo a chemical changeonce they reach theatmosphere

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Criteria Pollutants:Source of CO

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Source of NOX

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Source of Lead

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Secondary Pollutants

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Welfare Effects - Acid Rain

Acid rain" is a broad term used todescribe several ways that acids fall

out of the atmosphere

A more precise term is aciddeposition, which has two parts: wetand dry

Acid deposition occurs when

emissions of sulfur dioxide andnitrogen oxides in the atmosphere

react with water, oxygen, and oxidantsto form acidic compounds

These compounds fall to the earth ineither dry form (gas and particles) orwet form (rain, snow, and fog)

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Acid Rain

Acidity is measured in terms of pH on a

logarithmic scale from 1.0 to 14.0

A pH of 1.0 indicates high acidity, whereas a pHof 14.0 indicates high alkalinity; a pH of 7.0

indicates a neutral solution

Precipitation falling through a "clean"atmosphere is normally somewhat acidic, with apH of about 5.6. Acid rain, however, can have apH values below 4.0.

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Welfare Effects - Greenhouse Effect

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Greenhouse effect

The earth's climate is fueled by the sun

Most of the sun's energy, called solar radiation, isabsorbed by the earth, but some is reflected back into

space

Clouds and a natural layer of atmospheric gasesabsorb a portion of earth's heat and prevent it fromescaping into space

This keeps our planet warm enough for life and isknown as the natural "greenhouse effect

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Global warming

Scientific evidence shows that the greenhouse

effect is being increased by the release ofcertain gases into the atmosphere that cause theearth's temperature to rise, This is called "globalwarming"

Carbon dioxide, methane, particulate matter(especially black carbon or soot), nitrous oxide,fluorinated compounds, and ozone are some of

the compounds contributing to global warming

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Effects of global warming Continued emissions of greenhouse gases could

cause a 2.5

to 10

Fahrenheit rise in temperatureby the year 2100

This could lead to more extreme weather eventssuch as droughts and floods, threaten coastal

resources and wetlands by raising the sea level,and increase the risk of certain diseases byproducing new breeding sites for pests andpathogens

Agricultural regions and woodlands are alsosusceptible to changes in climate that could resultin increased insect populations and plant disease

This degradation of natural ecosystems could lead

to reduced biological diversity

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Welfare Effects - Stratospheric Ozone Depletion

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Stratospheric Ozone Depletion

The stratosphere, located about 6 to 31

miles above the earth, contains a layer ofozone gas that protects living organismsfrom harmful ultraviolet-B radiation (UV-B)from the Sun

UV-B (280 to 315 nanometer wavelength)has been linked to many harmful effects

including various types of skin cancer,cataracts, and harm to some crops, certainmaterials, and some forms of marine life

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Ozone Depletion

In the mid-1970s, it was discovered that somehuman-produced gases could cause stratosphericozone depletion

Gases containing chlorine and bromine accumulatein the lower atmosphere, are eventually transported

to the stratosphere and then converted to morereactive gases that participate in reactions thatdestroy ozone

Several substances have been associated with thestratospheric ozone depletion, includingchlorofluorocarbons (CFCs), halogens, carbontetrachloride, methyl bromide, and methylchloroform

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ozone depletion One example of ozone depletion is the annual ozone

"hole" over Antarctica that has occurred during theAntarctic spring since the early 1980s

Rather than being a literal hole, the ozone hole is alarge area of the stratosphere with extremely low

amounts of ozone

Ozone levels fall by over 60% during the worst years

Even over the United States, ozone levels are about 3percent below normal in the summer and 5 percentbelow normal in the winter

W lf Eff t S

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Welfare Effects Smog

It is the mixing of smoke particles from industrialplumes with fog that produces a yellow-blackcolor near ground level

Under the right conditions, the smoke and sulfur

dioxide produced from the burning of coal cancombine with fog to create industrial smog

The burning of fossil fuels like gasoline cancreate another atmospheric pollution problemknown as photochemical smog

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Photochemical smog

Photochemical smog is a condition that developswhen primary pollutants (oxides of nitrogen and

volatile organic compounds created from fossilfuel combustion) interact under the influence ofsunlight to produce a mixture of hundreds ofdifferent and hazardous chemicals known assecondary pollutants

Smog is the brownish haze that pollutes our air,particularly over cities in the summertime

Smog can make it difficult for some people tobreathe and it greatly reduces how far we cansee through the air.

Effects of smog

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Effects of smog Smog is a mixture of pollutants with ground-level ozone being

the main culprit

Increased levels of ground level-ozone are generally harmful toliving systems because ozone reacts strongly to destroy oralter many other molecules

Excessive ozone exposure reduces crop yield and forestgrowth

It interferes with the ability of plants to produce and store food,reducing overall plant health and the ability to grow andreproduce

The weakened plants are more susceptible to harsh weather,

disease, and pests

In addition, increases in tropospheric ozone lead to a warmingof earth's surface.

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Chemistry of pollutants

some equations and descriptions of the chemicalreactions that are involved in the production of commonprimary and secondary air pollutants.

Reactions producing:

Carbon Dioxide (CO2) Carbon Monoxide (CO)

Nitrogen Oxide (NO)Nitrogen Dioxide (NO2)

Ozone (O3)PAN gas (C2H3N2O5)Acid Rain (H2SO4)

Carbon Dioxide (CO2)

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Carbon Dioxide (CO2)

Carbon dioxide is mostly produced

through the burning of organic compounds(hydrocarbons). If these reactions arecomplete, the products are carbon dioxideand water

e.g. burning octane (petrol):

2C8H18 + 25O2 ==> 16CO2 + 18H2O

C b M id (CO)

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Carbon Monoxide (CO)

Carbon monoxide is mostly produced through the

incomplete burning of organic compounds(hydrocarbons). This occurs when the amount of oxygen available is

limited

e.g. burning octane (petrol):C8H18 + O2 ==> aCO2 + bCO + cH2O + unburnthydrocarbons

Where a, b, & cdepend on the amount of availableoxygen.

Nitrogen Oxide (NO)

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Nitrogen Oxide (NO)

Nitrogen oxide is produced through thecombination of oxygen and nitrogen from the airat very high temperatures.

This can occur naturally as the result of lightning

strikes but is more common in the hot cylindersof car engines as they burn fuel in air

Reaction:

N2 + O2(+high temperature ~ 2000 C) ==> 2NO

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Nitrogen Dioxide (NO2)Nitrogen dioxide is produced through the further reactionof nitrogen oxide with oxygen in the air.

This reaction is relatively fast and is increased further bythe presence of heat and sunlight.

Reaction: 2NO + O2 ==> 2NO2

Ozone (O3)Ozone in the troposphere (ground level) is producedfrom the combination of atmospheric oxygen.

This reaction is catalyzed by nitrogen dioxide andsunlight, making ozone a secondary pollutant.

Reaction: 3O2 ( + NO2 catalyst & sunlight) ==>2O3

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PAN gas (C2H3N2O5)PAN gas (peroxyacetalnitrate) is produced from thecombination of hydrocarbons, carbon dioxide and nitrogendioxide in the pressence of sunlight and heat. It has thefollowing structure:

Acid Rain (H2SO4)

Sulphuric acid is produced from the reaction of sulphurdioxide with ozone, the resulting sulphite ions then reactwith water vapour in the atmosphere to produce sulphuricacid.

Reactions: SO2 + O3 ===> SO3 + O2 SO3 + H2O ===> H2SO4

S ki i i j i t h lth

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Smoking is injurious to health

Which is dangerous to health, either

indoor smoking or out door smoking?The concentration of pollutants in the self

polluted air in a room of a smoker is higher

than that of out doors

What it contains?

Tobacco smoke contains at least 7polycyclic hydrocarbons and radioactivepolonium-210, which are carcinogens

S ki i i j i h l h

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Smoking is injurious to health

What are the health effects?

In smokers, the risk of developing anddying from lung cancer10 timesmorethan a non-smoker

The risk of lung diseasesis 6 timesandthat of heart diseasestwiceas comparedto a non-smoker.

Certain other diseases are also related tosmoking

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Smoking is Sweet poison

Who will be affected by smoking?

There is a world wide campaign to prohibitsmoking in public places as smokers affect

the health of even non-smoker, calledpassive smoker( i.e. who inhale tobaccosmoke passively)