2SyllabusAir Pollution, Composition of Air, Structure of atmosphere, Ambient air quality standards, Classification of air pollutants, Sources of common air pollutants like SPM, SO2, NOX, Natural and anthropogenic Sources, and its effects.
3Air Pollution Definition:- Air pollution is define as “ Excessive concentration of foreign matter in air, which adversely affects the well being of individuals or causes damage to the property”.
5Atmosphere and its Structure Atmosphere:- The gaseous layer surrounding the earth is known as atmosphere.The atmosphere is the life supporting mantle, surrounding the earth.The atmosphere surrounds the earth up to 700 km, atmosphere is subdivided as
6Troposphere:- ( 0 To 12 Km) Contains 75 % of the gases in the atmosphere. This is where we live and weather occurs.Stratosphere:- (12 – 50 Km) this layer contains ozone layer. Ozone acts as a shield for the earth’s surface. It absorbs ultraviolet radiations from the sun. This causes temperature increase in the upper part of the layer.Mesosphere:- ( 50 to 80 Km) This is the coldest region of the atmosphere. This layer protects the earth from meteoroid. They burn up in this area.
7Thermosphere:- ( 80 Km and above) The air is very thin in this region Thermosphere:- ( 80 Km and above) The air is very thin in this region. Thermosphere means “Heat Sphere”. The temperature is very high in this regionThis layer contains:-(a) Ionosphere:-This is the lower part of the thermosphere. It extends from 80 Km – 550 Km. This layer generally helps in radio communication.(b) Exosphere:- The upper part of the thermosphere. It extends from 550 km and above. Air is very thin here this is the area where satellite orbits the earth.
9Ambient air Quality Standards * Ministry of Environment and Forests, Government of India notification,1994** Particle size less than 10 µmAmbient air Quality StandardsPollutantTime Weighted Average Concentration in Ambient AirIndustrial AreaResidential, Rural and otherSensitive Area Sulphur Dioxide (SO2) Annual 24 hours 80 µg/m3 120 µg/m3 60 µg/m3 80 µg/m3 15 µg/m3 30 µg/m3Oxides of Nitrogen (NO2) 15 µg/m3 30 µg/m3Suspended Particulate Matter (SPM) Annual 360 µg/m3 500 µg/m3 140 µg/m3 200 µg/m3 70 µg/m3 100 µg/m3Respirable ** Particulate Matter (RPM) Annual 24 hours 120 µg/m3 150 µg/m3 60 µg/m3 100 µg/m3 50 µg/m3 75 µg/m3Lead (pb) 1.0 µg/m3 1.5 µg/m3 0.75 µg/m3 1.00 µg/m3 0.50 µg/m3Carbon Monoxide(CO) 8 hours 1 hour 5.0 µg/m3 10.0 µg/m3 2.0 µg/m3 4.0 µg/m3
10Major Sources of Air Pollution 1) Natural Sources:- The natural sources of air pollution are volcanic eruptions, releasing of poisonous gases like SO2 ( Sulfur dioxide), Hydrogen sulphide (H2S), Carbon Monoxide(CO), Forest fires, natural organic and inorganic decays, Pollen grains, wind blown dust, among them pollen grain are important because it causes allergic reactions in individuals.
11Anthropogenic sources (a) Rapid Industrialization:- The Industries such as pulp and paper, chemical, metallurgical plants, refineries are responsible for air pollution, the most common pollutants are CO2, SO2, CO, NO, H2S etc.(b) Transportation:- Automobile exhausts release smoke. The smoke is a result of incomplete combustion of carbonaceous matter. The common pollutants are CO ( Carbon Monoxide), CO2, and Hydrocarbons.
12(c) Burning of Fossil fuels and fires:- The conventional sources of energy are wood, coal, and fossil fuels. The byproducts of fossil fuels is nothing but poisonous gases such as CO, CH4 (methane), SO2, and NOX.(d) Deforestation:- The balance of O2 and CO2 is maintained in the nature by the vegetation. The deforestation by man for his own needs has disturbed the balance of CO2 and O2, Concentration.
13(e) Increase in Population:- an increase in population leads to global warming and emission of green house gases. It also contributes to losses in forest cover and loss of wild life.(f) Agriculture activities:- Various pesticides and insecticides are used for agricultural purposes. Thus they cause air pollution.(g) Radioactive fallout:- Nuclear reaction, nuclear weapon testing contributes towards Nuclear pollution. Nuclear Pollutants are very harmful to man, animals and vegetations.
14Classification of air pollutants Air pollutants are broadly classified as(a) According to origin(b) According to chemical composition(c) According to State of matter.
15According to Origin Air Pollutants can be classified as (a) Primary Pollutants(b) Secondary PollutantsPrimary Pollutants:- Primary pollutants are those which are directly emitted from identifiable sourceThese pollutants are emitted directly to the atmosphere.
16Ex:- (a) Particulate matter (b) Oxides of Sulphur (c) Oxides of Nitrogen(d) Carbon Monoxide(e) Radioactive Compounds
17Secondary air pollutants:- Secondary air pollutants are those which are produced in the air by the reaction of two or more primary pollutants.Ex:-OzoneFormaldehydePhotochemical smogPeroxy acetyl nitrate (PAN)
18According to Chemical Composition All the air pollutants are classified as(a) organic pollutants(b) In organic pollutants(a) Organic Pollutants:- Organic Pollutants contain carbon and hydrogen.Ex:-Hydro CarbonAldehyde and KetonesAlcoholsOrganic Sulphur compounds
19Inorganic Pollutants:- Inorganic compounds mainly includes (a) Carbon monoxide (CO)(b) Carbon dioxide (CO2)(c)Carbonates(d) Oxides of sulphur, nitrogen(e) Ozone
20According to State of Matter Air pollutants according to state of matter are classified as(a) Natural Contaminants(b) Particulate matter(c) Gases and vapours
21Natural ContaminantsThe air contaminants which are produced from natural sources are called natural contaminantsEg. Pollen grains are emitted from weeds, grasses and treesThis pollen grains are irritating to some individualsSize of pollen grains = 10 to 50 (µ)
22Particulate matterThese may be liquid or solid. The particulate matter are identified as aggregates which are larger than µ but smaller than 500 µ(a) Dust (1 To 10,000 µ) : Small solid particles resulting from break up of large masses through processes such as crushing, grinding or blasting.(b) Smoke ( 0.5 To 1 µ) Consist of finely divided solid particles produced by incomplete combustion of organic particles such as coal, wood, or tobacco.
23Mist:- These are liquid particles formed by condensation of vapor Fog (1 to 40 µ ):- High concentration of mist is called as fog. It is dispersion of liquid particles in air.Fumes ( 0.03 to 0.3 µ ):- Fine solid particles formed by the condensation of vapors of solid material. The fumes are generally emit from melting operations.Ash ( 1 to 1000 µ ):- fine, noncombustible particles are known as fly ash.Spray (10 to 1000 µ):- Liquid particles formed by automation
24Gases And Vapors(a) Carbon Monoxide:- (CO) This is an odorless, tasteless and colorless gas formed due to incomplete combustion of carbonaceous matter. The sources of carbon monoxide are motor vehicles, burning of fossil fuel and industrial processes.(b) Oxides of Sulphur:- They Include 4 different gaseous compounds such as Sulfur monoxide ( SO), Sulfur dioxide ( SO2), Sulphur trioxide ( SO3) and sulphur tetra oxide (SO4).Sulphur dioxide is a colorless, non flammable gas with suffocating odor.
25Oxides of NitrogenOxides of Nitrogen Include 4 gaseous compound:- Nitric oxide ( NO), Nitrogen dioxide (NO2), Nitrous Oxide (N) Nitrogen penta oxide (N2O5)In air pollution, Nitric oxide (NO) and Nitrogen dioxide are of prime concern.The sources of this pollutants are Industrial Processes, automobile exhausts.
26HydrocarbonOrganic compounds containing only carbon and hydrogen are classified as Hydrocarbons.They are of 2 types.(a) Aliphatic hydrocarbon(b) Aromatic hydrocarbonHydrocarbon present in the atmosphere in the atmosphere from both natural and man made sources.The major sources of hydrocarbon is burning of gasoline and industrial processes.
27Effects of some common air pollutants 1) Particulate Matter:-Effects on human:-The pollutants of size less than 1 µ causes lung damageAsbestos fibers causes cancerLead from automobile exhaust affects brainIt causes several respiratory diseasesSilica , arsenic, dust causes cancer
28Effects on plants:-Deposition of particulate matter containing toxic metals affects the growth of plantsThe particulate matter after deposition on plant leaves block stomata opening of plants and reduce plant growth.The particulate matter with acid rain, reduces pH of the soil which makes the infertile.
29Effect on Material:The particulate matter causes damage to buildingThe corrosion is enhancedIt causes cracks and fading of pointed surfaceParticulates accumulate on the soil and reduces fertility of soil.
30Carbon Monoxide Effects on humans:- The high concentration of CO can cause deathThe combination of CO and hemoglobin leads to the formation of carboxylhaemoglobin (COHb) reduces the oxygen carrying capacity of blood.At concentration of 100 ppm people experience dizziness and headache.The cigarette smoke contains 400 to 450 ppm CO the percentage of COHb in blood of cigarette smokers increases with increase in smoking.At concentration of 750 ppm of CO it will cause death.
31Effects on plants:-CO reduces nitrogen fixing capacity of bacteria. Which affects the plant growth.High concentration of causes leaf drops, reduces the size of leaf and ageingEffects on materials:-Carbon monoxide appears to have no detrimental effect on materials.
32Oxides of Sulphur Effects on human health:- It causes irritation of eyes and respiratory tracts.Increase in SO2 concentration in the atmosphere, may lead to lung cancerSO2 may obstruct breathingSO2 leads to the formation of H2 SO4 which is 20 times more irritant than SO2
33Effects on Plants:-The low concentration for long period may cause discoloration of leavesSO2 affects the growth of plantsAt high concentration the leaf tissues gets damaged.H2SO4 is extremely toxic to plants and soil fertility.
34Effects on materials:- The sulphuric acid will attack building materials containing carbonates. This will form CaSO4 the CaSO4 gets easily washed away leaving discolored surfacePaper absorb SO2 causing the paper to become brittleLeather looses the strength and flexibility.
35Oxides of NitrogenEffects on Human Health: nitric Oxide reduces the Oxygen carrying capacity of blood.Nitrogen dioxide causes irritation of lungsHigh level of NOx causes pneumonia, lung cancer, oxygen deficiency.NOx causes irritation of respiratory system, nervous system and digestive tracts.NOx is extremely dangerous to human health.
36Effects on vegetation:- NO2 and primary pollutants can damage plant tissuesHigh concentration of NO Causes Damage to leaves.Secondary Pollutants such as smog, O3 may damage the vegetationEffects on materials:-Nitric acid causes corrosion to metal surfaceNO2 fades the color of clothesNO2 causes cracking of rubber
37Hydrocarbon Effects on human health:- Aromatic hydrocarbon may lead to cancerInhalation of hydrocarbon causes irritation of respiratory tract.Methane creates narcotic effects on human beingsMost of the hydrocarbon are carcinogenic to lungs
38Effects on Vegetation:- HC affects plant growthDiscoloration of leavesEffects on Materials:-It causes discoloration of materialsMaterial becomes less elastic and more brittle.