| Major Global Environmental Issues | | | | drought and plunging agricultural yields in parts of |
| 1. Air pollution addition of harmful substances to the | | | | Africa, for example. |
| atmosphere resulting damage to the environment, | | | | Warmer temperatures are expected to partially melt |
| human health and quality of life. One of many forms | | | | the polar ice caps, leading to projected sea level rise |
| of pollution, air pollution occurs inside homes, schools, | | | | of 50cm (20 in) by the year 2050. A sea level rise of |
| and offices, in cities, across continents; and even | | | | this magnitude would flood coastal cities, force |
| globally. Air pollutions make people sick-it causes | | | | people to abandon low- lying islands, and completely |
| breathing problems and promote cancer and it harms | | | | inundate coastal wetlands. If sea level rise as |
| plants animals, and the ecosystems in which they live. | | | | projected rates, the Florida Everglades will be |
| Some air pollution return to earth in the form of acid | | | | completely under water in less than 50 years. |
| rain and snow, which corrode statues and buildings, | | | | Diseases like malaria, which are present are primarily |
| damage crops and forests, and make lakes and | | | | found in the tropics, may become more common in |
| streams unsuitable for fish and other plant and other | | | | the regions of the globe between the tropics and the |
| life. | | | | polar regions, called the temperate zones. For many |
| Pollution is changing the earth's atmosphere so that it | | | | of the world's plant species, and for animal species |
| lets in more harmful radiation from the sun. At the | | | | that are not easily able to shift their territories, as |
| same time, our polluted atmosphere is becoming a | | | | their habitat grows warmer, climate change may bring |
| better insulator, preventing heat from escaping back | | | | extinction. |
| into space and leading to a rise in global average | | | | 8 INDOR AIR POLLUTION: - Pollution is perhaps most |
| temperatures. Scientists predict that the temperature | | | | harmful at an often unrecognized |
| increase, refereed to as global warning will affect | | | | site inside the homes and buildings where we spend |
| world food supply after sea level, make weather | | | | most of our time. Indoor pollutants include tobacco |
| more extreme, and increase the spared of tropical | | | | smoke; radon an invisible radioactive gas that |
| disease. | | | | enters home from the ground in some regions; and |
| | | | | chemicals released from synthetic carpets and |
| 2.MAJOR POLLUTANT SOURCES: Most air pollution | | | | furniture, pesticides, and household cleaners. When |
| comes from one human activity: burning fossil- fuels | | | | disturbed, asbestos, a nonflammable material once |
| natural gas, coal, and oil to power Industrial | | | | commonly used in insulation, sheds airborne fibers |
| processes and motor vehicles. Among the harmful | | | | that can produce a lung disease called asbestosis. |
| chemical compounds this burning puts into the | | | | Pollutant may accumulate to reach much higher levels |
| atmosphere carbon dioxide, carbon monoxide, | | | | than they do outside, where natural air currents |
| nitrogen oxides, supper dioxide, and tiny solid particles | | | | disperse them. Indoor air levels of many pollutant |
| including lead from gasoline additives called particles. | | | | may be 2 to 5 times, and occasionally more than 100 |
| Between 1900 and 1970 motor vehicle use rapidly | | | | times, higher than outdoor levels. These levels of |
| expanded, and emissions of nitrogen oxides, some of | | | | Indoor air pollutants are especially harmful because |
| the most damaging pollutant in vehicle exhausts | | | | people speed as much as 90 percent of their time |
| increased 690 percent. When fuels are completely | | | | living, working, and playing indoors, Inefficient or |
| burned, various chemicals called volatile organic | | | | improperly vented heaters are particularly dangerous. |
| chemicals (VOCs) also enter the air. Pollutants also | | | | California have imposed tougher air pollution standards |
| come from other sources. For instance, decomposing | | | | of their own |
| garbage in landfills and solid waste disposal sites emits | | | | Air Pollution: addition of harmful substances to the |
| methane gas, and many household product gives off | | | | atmosphere resulting in damage to the environment, |
| VOCs. | | | | human health, and quality of life. One of many forms |
| Some of these pollutants also come from natural | | | | of pollution, air pollution occurs inside homes, schools |
| sources. For example, forest fire emits particulars and | | | | and offices; in cities; across continents, and even |
| VOCs into the atmosphere. Ultra line dust particles, | | | | globally. Air pollution makes people sick- it causing |
| dialoged by soil erosion when water and weather | | | | breathing problems and promote cancer-and it harms |
| looser layers of soil, increase airborne particulate | | | | plants, animals, and they ecosystems in which they |
| levels. Volcanoes spew out sulfur dioxide and large | | | | live. Some air pollutants return to earth in the form of |
| amounts of pulverized lava rock known as volcanic | | | | acid rain and snow, which corrode statues and a |
| ash. A big volcanic eruption can darken the sky over | | | | building damage crops and forests, and makes lakes |
| a wide region and affect the earth; s entire | | | | and streams unsuitable for fish and other plant and |
| atmosphere. The 1991 eruption of mount pinatubo in | | | | animal life. |
| the Philippines, for example, dumped enough volcanic | | | | Pollution is changing the earth's atmosphere so that it |
| ash into the upper atmosphere to lower global | | | | lets in more harmful radiation from the sun. At the |
| temperatures for the next two years. Unlike | | | | same time our polluted atmosphere is becoming a |
| pollutants from human activity, however, naturally | | | | better insulator, preventing heat from escaping back |
| occurring pollutants tend to remain in the atmosphere | | | | into space and leading to rise in global average |
| for a short time and do not lead to permanent | | | | temperatures, Scientists predict that the temperature |
| atmospheric change. | | | | increase, referred to as global warming will affect |
| Once in the atmosphere, pollutants often undergo | | | | world food supply, alter sea level, make weather |
| chemical reactions that produce additional harmful | | | | more extreme, and increases the spread of tropical |
| compounds. Air pollution is subject to weather | | | | disease. |
| patterns that can trapit in valleys or blows it across | | | | II MAJOR POLLUTANT SOURCES: Most air pollution |
| the globe to damage pristine environments far from | | | | comes from one human activity; burning fossil fuels |
| the original sources. | | | | – natural gas, coal and oil to power industrial |
| 3.LOCAL AND REGIONAL POLLUTION: Local and | | | | processes and motor vehicles. Among the harmful |
| regional pollution take place in he lowest layer of the | | | | chemical compound this burning puts into the |
| atmosphere, the troposphere, which extends from | | | | atmosphere are carbon dioxide, nitrogen oxides, |
| the earth's surface to about 16 km (about 10 mi). | | | | carbon monoxide, sulfur dioxide, and tiny solid |
| The troposphere is the region in which most weather | | | | particles – including lead from gasoline additives |
| occurs. If the load of pollutants added to the | | | | – called particulates. Between 1900 and 1970, |
| troposphere were equally distributed, the pollutants | | | | motor vehicle used rapidly expanded, and emissions |
| would be spread over vast areas and the air pollution | | | | of nitrogen oxides, some of the most damaging |
| might almost escape our notice. Pollution sources tend | | | | pollutants in vehicles exhaust, increased 690 percent. |
| to be concentrated, however, especially in cities. In | | | | When fuels are incompletely burned, various |
| the weather phenomenon is known as thermal | | | | chemicals called volatile organic chemicals (VOCs) also |
| inversion, a layer of cooler air is trapped near the | | | | enter the air. Pollutants also come from other |
| ground by a layer of warmer air above. When this | | | | sources. For instance, decomposing garbage in landfills |
| occurs, normal air mixing almost ceases and pollutant | | | | and solid waste disposal sites emits methane gas, and |
| are trapped in the lower layer. Local topography, or | | | | many household products give off VOCs. |
| the shape of the land, can worsen this effect – | | | | Some of these pollutants also come from natural |
| an area ringed by mountains, for example, can | | | | sources. For example, forest fires emit particulates |
| become a pollution trap. | | | | and VOCs into the atmosphere. Ultra fine dust |
| | | | | particles, dislodged by soil erosion when water and |
| 4.Smog and Acid Precipitation: Smog is intense local | | | | weather loosen layers of soil, increase airborne |
| pollution usually trapped by a thermal inversion. | | | | particulates levels. Volcanoes spew out sulfur dioxide |
| Before the age of automobile, most smog came | | | | and large amounts of pulverized lava rock known as |
| from burning coal and was so serve that in 19th | | | | volcanic ash. A big volcanic cruption can darken the |
| century London, street light were turned on by noon | | | | sky over wide region affect the earth's entire |
| because soot and smoke darkened the midday sky. | | | | atmosphere. The 1991 eruption of Mount Pinatubo in |
| Burning gasoline in motor vehicle is the main source of | | | | the Philippines, for examples, for example, dumped |
| smog in most regions today. Powered by sunlight, | | | | enough volcanic ash intiya |
| oxide of nitrogen and volatile organic compound react | | | | In an effort to enforce pollution standards, pollution |
| in the atmosphere to produce photochemical smog. | | | | control authorized measure both the amounts of |
| Smog contains ozone, a form of oxygen gas made | | | | pollutants present in the atmosphere and the |
| up of molecules with three oxygen atoms rather | | | | amounts entering it from certain sources. The usual |
| than the two. Ozone in the lower atmosphere is a | | | | approach is to sample the open, or ambient, air and |
| poison- it damages vegetations, kills trees, irritates | | | | test it for the presence of specified pollutants. The |
| lung issues, and attacks rubber. Environmental officials | | | | amount of each pollutant is counted in parts per |
| measure ozone to determine the severity of smog. | | | | million or, in some cases, milligrams, or micrograms per |
| When the ozone level is high, other pollutants, | | | | cubic meter. To learn how much pollution is coming |
| including carbon monoxide, are usually present at high | | | | from specific sources, measurements are also taken |
| levels as well (see Air Quality). | | | | at industrial smokestacks and automobile tailpipes. |
| In the presence of atmospheric moisture, sulfur | | | | |
| dioxide and oxides of nitrogen turn into droplets of | | | | 9.Pollution is controlled in two ways: With end of the |
| pure acid floating in smog. These airborne acids are | | | | pipe devices that capture pollutants already created, |
| bad for the lungs and attack anything made of | | | | and by limiting the quantity of pollutants produce in |
| limestone, marble or metal. In cities around the world, | | | | the first place. End of the pipe devices include |
| smog acids are eroding precious artifacts, including | | | | catalytic converters in automobile and various kinds |
| the Parthenon temple in Athens, Greece, and the Taj | | | | of filters and scrubbers in industrial plants .In a |
| Mahal in Agra, India. Oxides of nitrogen and sulfur | | | | catalytic converters, exhaust gases pass over small |
| dioxide pollute place far from the points where they | | | | beads coated with metals that promote reaction |
| are released in the air. Carried by winds in the | | | | changing harmful substances into less harmful ones. |
| troposphere, they can reach distant regions where | | | | When and of the pipe devices first began to be |
| they descend in acid form, usually as rain or snow. | | | | used, they dramatically reduced pollution at a |
| Such acid precipitation can burn the leaves of plants | | | | relatively low cost. As air pollution standards become |
| and make lakes too acidic to support fish and other | | | | stricter, it becomes more and more expensive to |
| living things. Because of acidification, sensitive species | | | | further clean the air. In order to lower pollution |
| such as the popular brook trout can no longer survive | | | | overall, industrial polluters are sometimes allowed to |
| in many lakes and stream in the estern United States. | | | | make cooperative deals. For instance, a power |
| Smog spoil views and makes outdoor activity | | | | company may fulfill its control requirements by |
| unpleasant. For the very young, the very old, and | | | | investing in pollution control at another plant or |
| people who suffer from asthma or heart diseases, | | | | factory, where more effective pollution control can |
| the effects of smog are even worse. It may cause | | | | be accomplished at a lower cost. |
| headaches or dizziness and can cause breathing | | | | End –of-the –pipe controls, however |
| difficulties. In extreme cases, smog can lead to mass | | | | sophisticated, can only do so much. As pollution |
| illness and dearth, mainly from carbon monoxide | | | | efforts evolve, keeping the air clean will depend |
| poisoning. During a thermal inversion cause at least | | | | much more on preventing pollution than on curing it. |
| 3300 deaths. | | | | Gasoline, for instance, has been reformulated several |
| | | | | times to achieve cleaner burning. Various |
| 5.GLOBAL SCALE POLLUTION: Air pollution can | | | | manufacturing processes have been redesigned so |
| expand beyond a regional area to cause | | | | that less waste is produced. Car manufacturers are |
| global effects. The stratosphere is the layer of the | | | | experimenting with automobiles that run on electricity |
| atmosphere between 16 Km (10 mi) and 50 Km | | | | or on cleaner- burning fuels. |
| (30mi) above sea level. It is rich in ozone, the same | | | | The choices can have a significant impact on the |
| molecule that acts as a pollutant when found at | | | | state of the air. Using public transpiration instead of |
| lower levels of the atmosphere in urban smog. Up at | | | | driving for instance reduces pollution by limiting the |
| the stratospheric level, however ozone forms a | | | | number of pollution of emitting automobiles on the |
| protective layer that serves a vital function: it | | | | road. During periods of particularly intense smog, |
| observes the wavelength of solar radiation known as | | | | pollution control authorizes often urge people to avoid |
| ultraviolet- B (UV-B) UV-B damages deoxyribonucleic | | | | trips by car. To encourage transits use during bad air |
| acid (DNA), the genetic molecule found in every living | | | | periods, authorized in Paris, France make bus and |
| cell, increasing the risk of such | | | | subway travel temporary free. |
| problems as cancer in humans. Because of its | | | | Indoor pollution control must be accomplished |
| protective function the ozone layer it essential to life | | | | building-by-building or even room-by-room. Proper |
| on earth. | | | | ventilation mimics natural outdoor air currents, |
| 6.Ozone Depletion : Several pollutants attack the | | | | reducing levels of indoor air pollutants by continually |
| ozone layer. Chief among them is the class of | | | | circulating fresh air. After improving ventilation, the |
| chemicals known as chlorofluorocarbons (CFCs), used | | | | most effective single step is probably banning |
| as refrigerants (notably in air conditioners), as agents | | | | smoking in public rooms. Where asbestos has been |
| in several manufacturing processes, and formally as | | | | used in insulation, it can be removed or sealed behind |
| propellants in spray cans. CFC molecules are virtually | | | | sheathes so that it won't be shredded and get into |
| indestructible until they rich the stratosphere. Here, | | | | the air. Sealing foundations and installing special pipes |
| intense ultraviolet radiation breaks the CFC molecules | | | | and pumps can prevent radon from seeping into |
| apart, releasing the chlorine atoms they contain. | | | | buildings. |
| These chlorine atoms begin reacting with ozone, | | | | On the global scale, pollution control standards are the |
| breaking it down into ordinary oxygen molecules that | | | | result of complex negotiations among nations. |
| do not observe UV-B. The chlorine acts as a | | | | Typically, developed countries, having already gone |
| catalyst-that is, it takes part in several chemical | | | | through a period of rapid (and dirty) industrialization, |
| reactions- yet at the ends emerges unchanged and | | | | are ready to demand cleaner technologies. Less |
| able to react again. A single chlorine atom can | | | | developed nations, hoping for rapid economic growth, |
| destroy up to 100,000 ozone molecules in the | | | | are less enthusiastic about pollution controls. They |
| atmosphere. Other pollutants, including nitrous oxide | | | | seek lenient deadlines and financial help from |
| from fertilizers and the pesticide methyl bromide, also | | | | developed countries to make the expensive changes |
| attack atmospheric ozone. | | | | necessary to reduce pollutant emissions in their |
| Scientist are finding that under this assault the | | | | industrial processes. |
| protective ozone layer in the stratosphere is thinning. | | | | Nonetheless, several important international accords |
| In the Antarctic region, it vanishes almost entirely for | | | | have been reached. In 1988, the United State and 24 |
| a few weeks every year. Although CFC use has | | | | other nations agreed in the Long-Range Tran |
| been greatly reduced in recent years, CFC molecules | | | | boundary Air Pollution Agreement to hold their |
| already released in the lower atmosphere will be | | | | production of nitrogen oxides, a key contributor to |
| making their way to the stratosphere for decades | | | | acid rain, to current levels. In the Montreal Protocol, |
| and further ozone loss is expected. As a result, | | | | adopted in 1987 and strengthened in 1990 and 1992, |
| experts anticipate an increase in skin cancers, more | | | | most nations agreed to stop or reduce the |
| cataracts | | | | manufacture of OFCs. In 1992 the United Nations |
| | | | | Framework Convention on Climate Change |
| 7.GLOBAL WARMING :Humans are bringing about | | | | negotiated a treaty outlining cooperative efforts to |
| another global-scale change in the atmosphere: the | | | | curb global warming. The treaty, which took effect in |
| increase in what are called greenhouse gases. Like | | | | March 1994, has been legally accepted by 160 of the |
| glass in a greenhouse, these gases admit the sun's | | | | 165 participating countries. |
| light but tend to reflect back downward the heat | | | | In December 1997 at the Their Conference of the |
| that is radiated from the ground below, trapping heat | | | | United Nations Framework Convention on Climate |
| in the earth's atmosphere. This process is known as | | | | Change in Japan, more than 160 nations formally |
| the greenhouse effect. Carbon dioxide is the most | | | | adopted the Kyoto Protocol. This agreement calls for |
| significant of these gases-here is 25 percent more | | | | industrialized nations to reduce their emissions of |
| carbon dioxide in the atmosphere today than there | | | | greenhouse gases to levels 5 percent below 1990 |
| was a century ago, the result of out burning coal and | | | | emission levels between 2008 and 2012. The United |
| fuels derived from oil. Methane, nitrous oxide, and | | | | States, which releases more greenhouse gases than |
| CFCs are greenhouse gases as well. | | | | any other nation, has traditionally been slow to |
| Scientists predict that increases in these gases in the | | | | support such strong measures The U.S. Senate may |
| atmosphere will make the earth a warmer place. | | | | be reluctant to ratify the Kyoto Protocol because it |
| They expect a global rise in average temperature | | | | does not require developing countries, such as China |
| somewhere between 1.0º C (1.8º and 6.3º F) in | | | | and India, to meet similar emissions goals. |
| the next century. Average temperatures have in fact | | | | All these antipollution measures have helped stem the |
| been rising, and the years from 1987 to 1997 were | | | | increase of global pollution emission levels. Between |
| the warmest ten years on record. Most scientists are | | | | 1970, when the Clean Air Act was passed, and 1995, |
| reluctant to say that global warming has actually | | | | total emissions of the major air pollutants in the |
| begun because climate naturally varies from year to | | | | United States decreased by nearly 30 percent. During |
| year and decade to decade, and it takes many years | | | | the same 25-years period, the U.S. population |
| of records to be sure of a fundamental change. | | | | increased 28 percent and vehicle miles traveled |
| There is little disagreement, though, that global | | | | increased 166 percent. Air pollution control is race |
| warming is on its way. | | | | between the reduction of pollution form each source, |
| Global warming will have different effects in different | | | | such as a factory of a car, and the rapid multiplication |
| regions. A warmed world is expected to have more | | | | of sources. Some in American cities is expected to |
| extreme weather, with more rain during wet periods, | | | | increase again as the number of cars and miles driven |
| longer droughts, and more powerful storms. Although | | | | continue to rise. Meanwhile, developing countries are |
| the effects of future climate change are unknown | | | | building up their own industries, and their citizens are |
| some predict that exaggerated weather conditions | | | | buying cars as they can afford them. Ominous |
| may translate into better agricultural yields in areas | | | | changes continue in the global atmosphere. New |
| such as the western United States, where | | | | efforts to control air pollution will be necessary as |
| temperature and rainfall are expected to increase, | | | | long as these trends continue. |
| while dramatic decreases in rainfall may lead to server | | | | |