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Pollution is the addition of substances to the | : vou . at lear bie about, environment in quantities that are harmful to living | ae Le :, beings. It can be of different types. eee a, , Look at the pictures below. Identify and write the, type of pollution shown in each picture., , , , , , , , , pars erp rere, , , , , , ; 2 :, : 4., In this chapter, we will discuss air pollution and weter pollution in detail., wognged ss0N “y “veered sere “g Mogryed gue? 7 Legryes ay TST, ; z ‘ ‘

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ce, , ; poLLUTION, ", , a), , yb a ,, ° ir around us is : mixture of many gases and dust particles. The percentages of the, ‘or gases present in air are, , v), , nitrogen (78.08%) + Oxygen (20.95%), , carbon dioxide (0.03%) +” Other gases (0.97%), qatural processes and, to a larger extent, human activities, are responsible for the release, fyarious chemicals into the air. The presence of chemicals in the air in quantities harmful to, , man health and the environment is known as air pollution. Common air pollutants and, pei main sources are discussed below., , , , i, Cae tet, , Particulate matter consists of tiny particles suspended Chlorofluorocarbons (CFCs) or freons are commonly, , in air. Volcanic eruptions, dust storms, burning of used as coolants in refrigerators and air conditioners, fossil fuels in thermal plants, and forest fires are some and as propellants in aerosol spray cans. CFCs are also, of the natural sources of particulate matter. It is also used in home insulation, plastic foam, and throwaway, present in the exhaust fumes of automobiles and metallic cans., , power plants as soot, fly ash, and lead particles., , , , Burning of fossil fuels such as coal and petroleum in Burning of carbon-rich fuels such as firewood,, thermal power plants and automobiles releases oxides _ coal, and petroleum releases carbon dioxide and, of sulphur and nitrogen into the air. - carbon monoxide into the atmosphere.

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ffects © , Pollut ne 4 long-lasting effects On global Cr Fee le, Air pollution N28 far-reach! a hem, , nimals tus discuss some, global Warr incre ein the concentration of carbon, ws ae ne atmosphere is one of the major causes O an ene, coe “Scientists believe that 4 increase in the a grower ne Ra, an pom earbon dioxide and certain other gases i e Or, aerponsible fora phenomenon called global oe, Global war ing refers to the unnatural increase In the, Earth's surfac temperature. To understan how this sulside because the solar @, happens: let us first familiarize ourselves with the concept eee by the interiors ar, of the greenhouse effect. greenhouse ' re-emitted nto, , i the greenhouse, thus keeping it, The phenomenon whereby the Earth's atmosphere traps “This warmth is what, solar radiation because of the presence of gases such as ., carbon dioxide, water vapour, and methane is called the, greenhouse effect. Without the natural greenhouse, face would have been too cold to, , effect, the Earth's sur’, sustain life. It is the increase, , gases beyond natural limits, Figure 18.1 explains how the greenhouse €, , responsible for global warming., : 2., , inthe amoun, , , , , Sunlight penetrates, the atmosphere and, warms the Earth’s, , 1., , - surface., , t of greenhouse, , that is a cause for worry., ffect is, , , , ates the heat into the atmosphere,, , into space. Greenhouse gases such, bsorb some of the heat and., , The Earth's surface radi, some of which escapes, as carbon dioxide and methane al, send it back to the Earth., , , , When the concentrat, of greenhouse gases, increases inthe atmosphere, more., heat is trapped nea?, the Earth's surface,, This results in arise, inthe Earth’s surfa, temperature., , , , , , Fig. 18.1 Diagrammati it, tic representation of greenhouse effect and global warming

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f, , uses and possible effects of global warming are summarized in Table 18.1., Table 18.1 Causes and possible effects of global warming, , , , Ca, Tht Perri e aed, , * Increase in the Earth’s surface temperature, , , , , , , , , , , , peforestation, , F gumning of fossil fuels * Melting of polar ice caps, , r pelease of methane due to the breakdown |« Rise in global sea level resulting in flooding of, , of organic matter low-lying coastal regions vy, acid Rain,”, , we know that the Taj Mahal was built using white marble. If you visit this monument today,, u will find patches of black dirt on it. Scientists believe that one of the major causes of, damage to this monument is a phenomenon called acid rain. Let us understand what acid, , in is., , When air pollutants such as oxides of sulphur and nitrogen react with oxygen and water, vapour of the atmosphere, they eventually form dilute solutions of sulphuric acid and nitric, acid, respectively. These acids mix with rainwater and come down in the form of acid rain., Acid-forming gases and acid rain have been known to result in, , destruction of vegetation due to acidification of soil;, , + accelerated leaching of rocks and soils;, , + decay of limestone, marble, and other building, materials; and, , + damage to the human respiratory system., , Word Help, , , , Depletion of the Ozone Layer, The ozone layer in the atmosphere protects both plant and animal life'‘on Earth by, , absorbing harmful ultraviolet radiation of the sun, which may cause skin cancer., “CFCs (also called freons) are responsible for the depletion of the ozone layer., , Effects on Plants, , Air pollution can have lasting and harmful effects on the growth and development of, plants. Some of these are discussed below., , Photochemical smog is said to have an adverse effect on plant growth because it forms, , er on leaves and, along with dust, blocks sunlight from being absorbed by the leaf, es and also affects, , a lay, surface. This layer blocks the absorption of carbon dioxide by the leav, , the functioning of stomata, thereby reducing the rate of photosynthesis., + Acid rain damages plants and can also cause premature leaf fall.

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Effects on Animals ‘, d into the atmosphere can cause and aggravate espirat,, 0, , The toxic air pollutants release :, human beings. Asthmatic patients, children, and e| es, , and cardiovascular diseases in Te Ee istons, i the harmful effects of air pollution. some, people are especially vulnerable to the h of the health, , effects of air pollution are given below., «Carbon monoxide easily combines with the haemoglobin in our blood and hampers, transport of oxygen within the body, which can lead to headache, drowsiness, dliésing, ess, , and nausea., , - Exposure to hig, nitrogen, and other air po, exposure to these air pollutants, asthma, and bronchitis., , h levels of suspended particulate matter, sulphur dioxide, oxides of, llutants irritates the eyes, nose, throat, and lungs. Years of, can lead to respiratory diseases such as lung cancer, , Prevention of Air Pollution, , Following are some of the steps that could be taken to prevent air pollution., , . Use of unleaded petrol should be encouraged., , Vehicles should be fitted with catalytic converters. The catalytic converter converts, harmful carbon monoxide and nitrogen oxides from vehicular exhaust to harmless, carbon dioxide, nitrogen dioxide, and water, before releasing the exhaust into the air, , - Less-polluting fuels such as CNG (compressed natural gas) should be used in vehicles, , Regular pollution-checks should be made mandatory for all vehicles., , Coal should be made free of sulphur before being burnt in power plants. Only lowsulphur coal should be used for burning., , Less-polluting energy resources such as hydroelectric energy and nuclear energy, , should be encouraged., + The use of public transport in cities should be encouraged.