Air Pollution Essay

IntroductionThe acress atmosphere, at or near sea train, consists approximately of 78 percent nitrogen, 21 percent oxygen and 1 percent other gases. If it were possible to remain in this state, 100 percent clean house direct would result. However, many varied sources exclusivelyow other gases and particulates to mix with the clean air, causing our atmosphere to fashion unclean or polluted. Some of these pollutants are visible while others are invisible, with each having the capability of causing distress to the eyes, ears, throat, come up and respiratory system. Should these pollutants become concentrated in a specific domain and under certain conditions, death could result due to the displacement or chemical change of the oxygen content in the air. These pollutants abide also cause great stultification to the environment and to the many man made objects that are heart-to-heart to the elements. To better understand the causes of air pollution, the pollutants can be catego rized into 3 separate display cases, natural, industrial and automotive.Natural PollutantsNatural pollution has been present on state since before man appeared and continues to be a factor when discussing air pollution, although it causes only a small percentage of the overall pollution problem. It is the direct result of decaying radical matter, wind born smoke and particulates from such natural events as plain and forest fires (ignited by passionateness or lightning), volcanic ash, sand and dust which can spread over a large area of the countryside.Such a phenomenon of natural pollution has been seen in the form of volcanic eruptions, with the resulting plume of smoke, steam and volcanic ash blotting out the suns rays as it spreads and rises higher into the atmosphere. As it travels into the atmosphere the upper air currents catch and carry the smoke and ash, while distil the steam brook into water vapor. As the water vapor, smoke and ash travel on their journey, the smoke dissipates into the atmosphere while the ash and moisture dissolve back to earth in a trail hundreds of miles long. In some cases, lives are lost and millions of dollars of property damage result.Industrial PollutantsIndustrial pollution is caused generally by industrial processes, the anxious of coal, oil and natural gas, which in turn produce smoke and fume. Because the burning give notices contain large amounts of sulfur, the principal ingredients of smoke and fumes are sulfur dioxide and particulate matter. This type of pollutant occurs most stark(a)ly during still, damp and cool weather, such as at night. Even in its less severe form, this pollutant is non confined to just cities.Because of air operatements, the pollutants move for miles over the surrounding countryside, leaving in its path a barren and unhealthy environment for all living things. Working with Federal, State and Local mandated regulations and by carefully monitoring emissions, big business has greatly r educed the amount of pollutant introduced from its industrial sources, striving to vex an acceptable direct. Because of the mandated industrial emission clean up, many land areas and streams in and around the cities that were formerly barren of vegetation and life, have now begun to move back in the direction of natures intended balance.Automotive PollutantsThe third major source of air pollution is automotive emissions. The emissions from the internal combustion engines were not an appreciable problem years ago because of the small number of registered vehicles and the nations small highway system. However, during the early 1950s, the trend of the American people was to move from the cities to the surrounding suburbs. This caused an immediate problem in transportation because the majority of suburbs were not afforded mass transit conveniences. This lack of transportation created an attractive market for the automobile manufacturers, which resulted in a dramatic increase in the nu mber of vehicles produced and sold, along with a marked increase in highway construction between cities and the suburbs.Multi-vehicle families emerged with a evolution emphasis placed on an individual vehicle per family member. As the increase in vehicle ownership and usage occurred, so did pollutant levels in and around the cities, as suburbanites drove daily to their businesses and employment, returning at the end of the day to their homes in the suburbs. It was noted that a smoke and fog type haze was being make and at times, remained in suspension over the cities, taking time to dissipate. At beginning this smog, derived from the words smoke and fog, was thought to result from industrial pollution simply it was determined that automobile emissions shared the blame.It was discovered that when normal automobile emissions were exposed to sunlight for a period of time, complex chemical reactions would take place. It is now cognise that smog is a photo chemical layer which develo ps when certain oxides of nitrogen (NOx) and unburned hydrocarbons (HC) from automobile emissions are exposed to sunlight. Pollution was more severe when smog would become stagnant over an area in which a warm layer of air settled over the top of the cooler air mass, trapping and guardianship the cooler mass at ground level. The trapped cooler air would keep the emissions from being dispersed and diluted through normal air flows. This type of air stagnation was given the name Temperature Inversion.TEMPERATURE INVERSIONIn normal weather situations, surface air is warmed by horniness radiating from the earths surface and the suns rays. This causes it to rise upward, into the atmosphere. Upon rising it will cool through a convection type heat exchange with the cooler upper air. As warm air rises, the surface pollutants are carried upward and dissipated into the atmosphere. When a temperature inversion occurs, we find the higher air is no longer cooler, however is warmer than the sur face air, causing the cooler surface air to become trapped. This warm air blanket can extend from above ground level to a few hundred or even a few thousand feet into the air. As the surface air is trapped, so are the pollutants, causing a severe smog condition. Should this stagnant air mass extend to a few thousand feet high, enough air movement with the inversion takes place to reserve the smog layer to rise above ground level but the pollutants still cannot dissipate.This inversion can remain for days over an area, with the smog level only rising or lowering from ground level to a few hundred feet high. Meanwhile, the pollutant levels increase, causing eye irritation, respiratory problems, reduced visibility, plant damage and in some cases, even disease. This inversion phenomenon was first noted in the Los Angeles, California area. The city lies in terrain resembling a basin and with certain weather conditions, a cold air mass is held in the basin while a warmer air mass covers it like a lid. Because this type of condition was first documented as prevalent in the Los Angeles area, this type of trapped pollution was named Los Angeles Smog, although it occurs in other areas where a large concentration of automobiles are used and the air remains stagnant for any length of time.HEAT TRANSFERConsider the internal combustion engine as a machine in which raw(prenominal) materials must be placed so a finished product comes out. As in any machine operation, a certain amount of work-shy material is formed. When we relate this to the internal combustion engine, we find that through the input of air and fuel, we obtain power during the combustion process to drive the vehicle. The by-product or waste of this power is, in part, heat and exhaust gases with which we must dispose. The heat from the combustion process can rise to over 4000F (2204C). The dissipation of this heat is controlled by a ram air effect, the use of cooling fans to cause air flow and a liquid coola nt solution surrounding the combustion area to transfer the heat of combustion through the cylinder walls and into the coolant.The coolant is because directed to a thin-finned, multi-tubed radiator, from which the excess heat is transferred to the atmosphere by 1 of the 3 heat transfer methods, conduction, convection or radiation. The cooling of the combustion area is an important part in the control of exhaust emissions. To understand the behavior of the combustion and transfer of its heat, determine the air/fuel charge. It is ignited and the flame front burns progressively across the combustion chamber until the burning charge reaches the cylinder walls. Some of the fuel in contact with the walls is not hot enough to burn, thereby snuffing out or quenching the combustion process.This leaves unburned fuel in the combustion chamber. This unburned fuel is then forced out of the cylinder and into the exhaust system, along with the exhaust gases. Many attempts have been made to minim ize the amount of unburned fuel in the combustion put up due to quenching, by increasing the coolant temperature and lessening the contact area of the coolant around the combustion area. However, design limitations within the combustion chambers prevent the complete burning of the air/fuel charge, so a certain amount of the unburned fuel is still expelled into the exhaust system, regardless of modifications to the engine.