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Reasons for Pollution
•Human population size has grown enormously over the last hundred years. This means increase in demand for food, water, home, electricity, roads, automobiles and numerous other commodities.
•These demands are exerting tremendous pressure on our natural resources, and are also contributing to pollution of air, water and soil.
•The challenge is to check the degradation of natural resources without halting the process of development.
•Pollution is an unwanted change in physical, chemical or biological characteristics of air, land, water or soil.
•In order to control environmental pollution, the Government of India has passed the Environment Protection Act, 1986 to protect and improve the quality of our environment.
Effect of Air polution
•We are dependent on air for our respiratory needs. Air pollutants cause injury to all living organisms.
•They reduce growth and yield of crops and cause premature death of plants.
•Air pollutants also affect the respiratory system of humans and of animals. Harmful effects depend on the concentration of pollutants, duration of exposure and the organism.
•Thermal power plants, smelters and other industries release gaseous air pollutants together with harmless gases, such as nitrogen, oxygen, etc.
•These pollutants must be separated/ filtered out before releasing the harmless gases into the atmosphere.
•We are seeing a bus or car or tempo on the road releasing black smoke . These automobiles are also a major cause for atmospheric pollution.
Control of Air polution
•Actually it is the poorly maintained old automobiles that are a major cause of air pollution. This happens when engine is not burning the fuel completely or properly. It can also happen because of improper mixture of air and fuel.
•Catalytic converters, having expensive metals namely platinum-palladium and rhodium as the catalysts, are fitted into exhaust system for reducing emission of poisonous gases.
Catalytic converter
•As the exhaust gases pass through the catalytic converter, un-burnt hydrocarbons are converted into carbon dioxide and water. Also, carbon monoxide and nitric oxide are changed to carbon dioxide and nitrogen gas, respectively.
•Motor vehicles equipped with catalytic converter should use unleaded petrol because lead in the petrol reduces effectiveness of the catalyst.
Air polution: Case Study of New Delhi
•With its very large population of vehicles, New Delhi leads the country in its levels of air-pollution. It has more cars than the states of Gujarat and West Bengal put together.
•Supreme Court, under its directives, the government was asked to take, within a specified time period, appropriate measures, including switching over the entire fleet of public transport, to CNG.
•It was nice that the government of Delhi decided to convert all the buses of to run on CNG by the end of 2002.
•This resulted in dramatic improvement in the pollution levels.
•CNG burns most efficiently and completely. On the other hand petrol or diesel are partly left un burnt. Moreover, CNG is cheaper than petrol or diesel.
Solution for reducing vehicular pollution include
Scrapping of old vehicles,
use of unleaded petrol,
use of low-sulphur petrol and diesel,
use of catalytic converters in vehicles .
Air polution: Bharat-6 Standard
•As per Bharat Stage-6 norms, the emission of carbon monoxide is to be reduced by 30% and NO2 by 80%.
•The BS-6 norms also sets limits for Hydrocarbon and particulate emissions, which were not specified in earlier norms.
•To meet the emission requirements of Bharat Stage-6, the carburettor in petrol engines need to be replaced by the programmed fuel injectors.
•To further reduce exhaust pipe emissions, the exhaust system would be fitted with three way catalytic converters.
•The norms also mandates On-Board Diagnostic System (OBD) for all BS-6 compliant vehicles. OBD is a computer system inside of a vehicle that tracks and regulates a car's performance.
•OBD collects information from the network of sensors inside the vehicle, which the system can then use to regulate car systems or alert the user to problems.
***End of Session 1 of Unit-5***
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