Sources and Effects of Air Pollution

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Air pollutionReference Notes
Sources and Effects of air pollution
For: Science Class 11 | Biology

The air pollution
Any undesirable change in physical, chemical, and biological character of air, which affects the living organisms, is called air pollution.

Sources and pollutants

Automobiles: Automobiles are the major sources of air pollution. In Nepal, there are more than two lakes automobiles and 50% of them are confined in Kathmandu valley. In the world, there are more than 300 million automobiles.

The main pollutants emitted form Automobiles are: CO2, CO, SO2, NOx, Hydro carbon compounds, aldehydes, acids, dusts, particulate matters, smoke, lead etc. In major cities 800 to 1000 tons pollutants per day produced from automobiles.

Industries: Sugar, Paper, Leather, Iron, Steel, Brick, Cement, Carpet, Plastic, Dyes manufacturing industries are also major sources of air pollution.

The pollutants emitted from industries are: CO, CO2, So2, NOx, Hydrocarbons acids, metals like Hg, Mn, Zn, Pb, Cd, smoke, dust etc. The Himal cement factory of Kathmandu produces about 5-6 tons dust per day.

Domestic resources: Burning firewood, crop residues, burning gas, stove, oils etc are also source of air pollution. These are indoor pollution.

The pollutants from domestic resources are: CO, CO2, So2, NOx, smoke, ashes etc.
Nepalese woman daily 6-8 hours expose to fire, but it is estimated that 3 hrs exposures provide smoke equivalent to 20 packets of cigarettes. Tobacco smoking is another indoor pollution from where CO, CO2, So2, NOx, hydrocarbons, and smokes are produced.

Effects of air pollution

CO: It is most dangerous air pollutant. It reacts with hemoglobin 210 times faster than oxygen forming carbamino hemoglobin. It reduces oxygen carrying capacity of blood causing disease called hypoxia. It reduces cellular respiration, mental activities, reduces leaf size, and destroys chlorophylls. 300 ppm of CO causes vomiting, 500 ppm causes coma and 1000 ppm causes death.

SO2: It causes eye irritation, air tract construction, vomiting, and headache, leaf reduction in plants and affects in stomata opening and causes acid rain.

NOx: It causes lungs damage, injuries to plants, oxide of nitrogen react with hydrocarbon in presence of UV rays forming peroxyacetyl nitrate (PAN) which is a toxic substance.

H2S: It causes headache, nausea, conjunctivitis, diarrhea, pneumonia, respiratory failure. High concentration of H2S in body causes coma and death.

CO2: It causes global warming i.e. increase earth’s temperature or green house effect.

Pb: it causes neurological problems; hematological problems i.e. destroy R.B.C. anemia, liver kidney diseases, dangerous in pregnancy, and high concentration of Pb in children affects neurology and hematological problems.

Zn: it is heavy metal which is injected in the atmosphere mainly from automobile exhaust when it react with air it gives zinc oxide fume which is toxic

Cd: it affects liver and kidney and increase blood pressure i.e. cause hyper tension, and cancer.

Hg: it damage brain eye and liver, cause headache, fatigue, loss of appetite.

HCs (benzene, benzopyrine, Methane etc): They cause respiratory diseases, lung cancer, and noise throat and eye problem

Ozone: it damage plant, reduces crop yield and it affect negatively in human health.

Smoke: smoke when react with water gives smog. It causes eye irritation, asthma, lung cancer etc.

Particulate matter: particulate matter like dust reduce visibility, damage plants and live stock, cause cancer and allergy.

Aerosol: aerosols are chemicals produced from jet or planes. The chemicals contain chlorofluorocarbon which destroys ozone layer.

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