Any physical chemical or biological change in the natural composition of air is termed as air pollution. Many deaths and respiratory diseases are occurred due to air pollution, though many techniques have been invented to control air pollution.
Sources of Air Pollution
Anthropogenic:
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1. Motor vehicles.
2. Combustion.
3. Chemical processes (Paper mills, Cements etc.).
4. Petroleum industry.
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5. Oil refiner aries.
6. Metallurgical process.
7. Agricultural activities.
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8. Nuclear energy systems.
9. Waste deposition and landfills, generate methane.
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Natural Sources
1. Methane emission by the digested food of animals.
2. Pine trees which emit Volatile Organic Carbons.
3. Dust from natural sources.
4. Smoke and CO2 from forest fires.
Air Pollutants are of 2 types
Primary Air Pollutant:
Those, which are directly, emitted from identifiable sources e.g. S02, Oxides of N, C02, Halogen compounds, Organic compounds and radioactive compound.
Secondary Air Pollutants:
These are produced in the air by two or more primary pollutants e.g. Ozone formaldehyde, PAN, Photochemical smog, Acid mist like H2S04.
Pollution from Ports Compared to Refineries, Power Plants, and Cars
Affects of Air Pollution
Environmental impact:
A. Smog formation (Smoke + fog)
N02 + HC Hv———– ► PAN + 03
Smog is produced when fuels are burnt. It refers to black smogy air which forbids breathing properly.
B. Acid rain:
Oxides of S and N gets oxidized in the atmosphere and after coming into contact with moisture gets converted into acid. They return to earth in the form of acid rain. It is harmful for metals, wildlife etc.
C. Global warming:
Due to industrial smoke the amount of C02, CH4, NOx, CFCs etc. rises and it results into the trapping of more and more heat around the globe which accelerates the pace of global warming.
D. O3 layer depletion:
Manmade activities have depleted the Ozone layer allowing more UV rays to pass through that affects our health and damages flora and fauna too.
Impact on Vegetation
It affects photosynthesis, causes:
(a) Chlorosis: It is redness in green pigment called chlorophyll.
(b) Necrosis: It is killing of tissues.
(c) C. Abscission: It is shedding of leaves from the plant.
(d) Epinasty: It is downward curvature of the leaf is termed as epinasty.
Health impact of air pollution:
Various diseases such as Hay fever, Asthma, allergic diseases, irritation of eyes, loss of co-ordination, damage to nervous system, and inflammation of skin are some of the diseases caused due to polluted air.
Control of Air pollution
1. Industries should be set up after proper environmental studies.
2. Industries should use low sulphur coal.
3. Removal of NO2 during the composition process.
4. Vehicles should use LPG and CNG in place of other fuel.
5. Use of biological filters (bio-scrubbers)
6. Planting more trees.