AIR POLLUTION

Introduction to Air Pollution

• Air pollution is not a new phenomenon.

• The first significant change in man’s effect on nature came with his discovery of fire

• The problem of air pollution came about when prehistoric man used fire for cooking, heating and light.

• The origin of our modern air pollution can be traced to 18th century and the birth of the Industrial Revolution

• The major air pollution problem of the 19th and early 20th centuries was the smoke and ash produced by burning fossil fuels at stationary power plants.

• The situation worsen with the increased use of automobiles.

Definition of Air Pollution

What is Air Pollution?

• It is the presence of undesirable material in air, in quantities large enough to produce harmful effects (this does not restrict to human causes).

• The undesirable materials may damage human health, vegetation, human property, or the global environment, as well as create aesthetic insults in the form of brown or hazy air or unpleasant smells.

Specific Definitions of Air Pollution

• “Air pollution is the excessive concentration of foreign matter in the air which adversely affects the well being of the individual or causes damagen to property.”

- American Medical Association

• “Air pollution is the presence in ambient atmosphere of sunstances, generally resulting from then activity of man, in suficient concentration, present for a sufficient time and under circumstances which interfere significantly with the comfort, health or welfare of persons or with the use or enjoyment of property.”

- Indian Standards Institution IS-4167 (1966)

Basic Physical Form of Air Pollution

i) Particles- Small, discrete masses of solid or liquid matter- E.g. dust, smoke, mists and fly ashes

ii) Gases- Widely separated molecules in rapid

motion- Lack definite shape

and volume- E.g. carbon monoxide,

sulphur dioxide and hydrocarbon vapors

Classifications of Pollutants

A general classification of air pollutants is as follows:– Particulate matter – Sulphur containing compounds : SO2,SO3,SOx & H2S

– Organic compounds :ketones,aldehydes,photochemical smog, O3

– Nitrogen-containing compounds : NO2, NOx, Acids

– Hydrocarbon : CO and CO2

– Halogen compounds : Br, Cl , F

– Radioactive compounds : Radon

– Odor– Lead

Primary & Secondary Air Pollutants

• Primary pollutants - those emitted directly from identifiable sources

• Secondary pollutants - produced in the air by the interaction among two or more primary pollutants, or by normal atmospheric constituents

Cause of Air Pollution

• Air pollution is waste remaining from human activities. Activities that contribute to air pollution are– Production of goods– Heat generation– Transportation (vehicles)

• The major cause of all air pollution is combustion.

• Perfect combustion - Hydrogen and carbon in the fuel combine with oxygen from air to produce heat, light, carbon dioxide, and water vapor.

• Impurities in the fuel, poor fuel-to-air ratio, or too high or too low combustion temperatures cause the formation of such side products such as– Carbon monoxide– Sulfur oxides– Nitrogen oxides– Fly ash– Unburned hydrocarbons-all air pollutants

Sources of Air PollutantSources classification may be based upon :(i) Whether the source is :

- stationary or mobile- combustion or non-combustion

(ii) Area or point(iii) The way that the source generates emission

Sources of CO – Vehicles smoke , Stack emissionSources of NOx – Reduction of organic nitrate, forest & fire , valcanoesSources of SO2 – coal and oil combustion in boiler and furnace, industrialprocess such as smelting, combustion in motor vehicles

Effects of Air Pollution

• Air pollution has a direct effect on human health.• Exposure to air pollution can cause both acute and

chronic health effects.

i) Chronic health effect - long-term- often not reversible

ii) Acute health effect - immediate- short-term- often reversible

Respiratory System

• Besides affecting the skin, eyes, and other body systems, pollutants affect the respiratory system primarily.

Human Respiratory System

• Both gaseous and particulate air pollutants can have negative effects on the lungs.

• Solid particles can settle on the walls of the trachea, bronchi, and bronchioles.

• Most of these particles are removed from lungs through the cleansing action of “cilia”.

• Cilia are small, hair-like outgrowths of cells, located on the walls of the lung.

Location of ‘Cilia’ in the Human Lungs

Continuous breathing of polluted air can • slow the normal cleansing action of the lungs

• result in more particles reaching the lower portions of the lung.

Damage to the lungs from air pollution can • inhibit the function of lungs

• contribute to the occurrence of respiratory diseases such as bronchitis, emphysema, and cancer.

Destruction mechanism of ozone by Cl radical from CFC compound is given below :

•Initiation : CFC will spilt up by UV radiation

CCl3F CCl2F + Cl •

•Propagation

Cl • + O3 O2 + Cl •

ClO • + O • O2 + Cl •

ACID RAIN

• The term "acid rain" means any precipitation made acidic by the dissolution of atmospheric acids with water, which can include fog, dew, sleet, and snow.

• The term "acid deposition" means the striking of any acidic solution, acidic gas, or acidic salt to Earth.

• Acid rain is generally a combination of the products of sulfur and nitrogen oxides, converted to sulfuric and nitric acids.

Typical reaction mechanisms of acid rain are as follows:

SO2 + 1/2O2 + H2O 2H+ + SO42- (aq)

2NO2 + 1/2O2 + H2O 2H+ + NO3- (aq)

• Wet deposition – Acidic rain, fog, and snow.

– As this acidic water flows over and through the ground, it

affects a variety of plants and animals.

• Dry deposition

– Acidic gases and particles.

– The wind blows these acidic particles and gases onto

buildings, cars, homes, and trees.

– Dry deposited gases and particles can also be washed from

trees and other surfaces by rainstorms.

– When this happens, the runoff water adds those acids to the

acid rain, making the combination more acidic than the

falling rain alone.

• Effects of acid rain– Buildings and outdoor monuments made of marble and limestone are now being gradually eroded away by acid rain.

– Many lakes have become so acidic that fish cannot live in them anymore.

– Degradation of many soil minerals produces metal ions that are then washed away in the runoff, causing several effects:

• The release of toxic ions, such as Al3+, into the water supply. • The loss of important minerals, such as Ca2+, from the soil, killing trees and damaging crops.

Global Warming

• Due to greenhouses effect, increase in greenhouse gases (CO2 etc) by burning fossil fuel

• Heat from sun get trapped

• Rise in global temperature rise in water temperature• Causes

– Death of aquatic organisms

Photochemical Smog

Photochemical smog

–Develops when primary pollutants (oxides of

nitrogen and volatile organic compounds created from

fossil fuel combustion) interact under the influence of

sunlight to produce a mixture of hundreds of different

and hazardous chemicals known as secondary

pollutants.

• Major toxic constituents of photochemical smog are NOx,

VOCs, O3, and peroxyacetyl nitrates (PAN).

• The formation of two most dominant toxic components; Ozone (O3) and peroxyacetyl nitrate (PAN).

Note the symbol R represents a hydrocarbon.

- NO acts to remove ozone from the atmosphere (occurs in unpolluted atmosphere)

O3 + NO NO2 + O2

NO + RO2 NO2 + other products

– Sunlight can break down NO2 back into NO.

NO2 + sunlight NO + O

– O formed in the above reaction then reacts with one of the abundant oxygen molecules producing ozone.

O + O2 O3

– NO2 can also react with radicals produced from VOCs to form toxic products such as PAN.

NO2 + R products such as PAN (general)

NO2 + CH3C(O)OO CH3C-OONO2

Effects of photochemical smog

• Short Term Exposure (1-2 Hours) may lead to:- Lung inflammation- Decreased ability to breathe, resulting in short shallow breaths, reduced athletic performance, pain upon breatheing deeply, coughing, chest tightness and discomfort- Increased susceptibility to respiratory diseases such as pneumonia and bronchitis- Increased sensitivity to allergens- Exacerbation of respiratory diseases such as asthma and emphysema

• Long Term Exposure may lead to: - High risk of lung disease

- Fibrosis: leads to less elastic lung and loss of functional tissue

- Premature lung aging - Risk of permanent decrease in lung

capacity

Clean Air Act Regulation 1978Clean Air Act Regulation 1978

Stack gas emission standardsStack gas emission standards

POLLUTANTS EMISSION SOURCES STANDARDS

1. Dark Smoke Solid Fuelled Equipment or facilities

Equipment using other types of fuel.

Ringelmann ChartNo 2

Ringelmann ChartNo 1

2. Dust Utilities used for the heating of Metals other than Cold Blast Foundry Cupola.

Facilities discharging dust containing asbestos and free silica.

Portland Cement Mfg: Kiln Clinker cooler, grinder, others.

Asphalt concrete/bituminous mixing plant: Stationary Plant Mobile Plant

Other sources

0.2 gm/Nm3

0.12 gm/Nm3

0.2 gm/Nm3

0.1 gm/Nm3

0.3 gm/Nm3

0.4 gm/Nm3

0.4gm/Nm3

3. Metal and metallic Compound:

3.1 Mercury

3.2 Cadmium

3.3 Lead

3.4 Antimony

3.5 Arsenic

3.6 Zinc

3.7 Copper

Industry

Industry

Industry

Industry

Industry

Industry

Industry

0.01 gm/Nm3

0.015 gm/Nm3

0.025 gm/Nm3

0.025 gm/Nm3

0.025 gm/Nm3

0.1 gm/Nm3

0.1 gm/Nm3

4. Gasesa) Acid gases

b) Sulphuric Acid Mist or SO3 or both

c) Chlorine gas

d) HCL

e) Fluorine, Hydrofluoric acid, inorganic fluorine compound

f) -do-

g) Hydrogen sulphide

h) NOx

i) -do-

Sulphuric Acid Mfg.

Any Sources other than a)

Any source

Any source

Aluminium Mfg from Alumina

Any source other than e)

Any source

Acid Nitric Mfg

Any source other than h)

3.5 gm of SO3/Nm3 and no persistent mist

0.2 gm of SO3/Nm3 and no persistent mist

0.2 gm of HCl/Nm3

0.4 gm of HCl/Nm3

0.2 gm of Hydrofluoric acid/Nm3

0.10 gm of Hydrofluoric acid/Nm3

5 ppm (Vol%)

1.7 gm of SO3/Nm3 and substantial colourless

2.0 gm of SO3/Nm3

Malaysia Ambient Air Quality Guidelines

 Pollutant and

Method 

 Averaging Time

 Air Quality Guidelines

 

ppm ug/m3

  

OzoneAs 2524

 

 1 hour

 

 0.10

 200

 8 hour

 

 0.06

 120

  

Carbon MonoxideAs 2695

 

 1 hour

 

 30

 35 #

 8 hour

 

 9

 10 #

RECOMMENDED MALAYSIA AIR QUALITY GUIDELINES,1989

# mg/m3