Essays

Eliminating pollution from the environment has not proved as easy as eliminating it from the pages of a book. Industry is now spending several billion dollars a year on pollution control. The first problem in understanding air pollution is to decide what is and what is not an air pollutant. Many of the things generally considered pollutants are present in the natural air. The amount of a substance locally present in the air is clearly important in defining a pollutant. Also the amount of harm or inconvenience caused by the substance and how long it remains in the atmosphere. These three factors are known as the three T's (tonnage, toxicity and time in the atmosphere).

A great deal of power is needed to run the factories of modern industrial nations. Automobiles, trains, planes and buses need power too. Nearly all of this power is produced in the same way—by burning fuels. The burning produces wastes. Some of the wastes get into the air, causing air pollution. The eventual fate of air pollution is to be wasted out into air. A smokestack with a billowing black plume, for years the proud symbol of industrial wealth and technological prowess, has in the last decade acquired another meaning. The puffing smokestack has come to signify the Achilles heel, rather than its strength.

Particulates of both natural and human origin also cause pollution. Smoke both natural from fires and human activities caused from industries and other sources are major and caused much damage. The chemicals that are most troublesome in air pollution are formed in the atmosphere by gases. The pollutant introduced into the atmosphere in the largest quantities by human activity is carbon monoxide. It is the product of incomplete combustion and the largest contribution comes from exhaust. Carbon monoxide is a colourless, odourless, tasteless gas, with the formula CO .

Carbon dioxide(CO2)  is also a product of combustion of fossil fuels. It is a minor constituent of natural air (about 0.03%), but the increased use of fossil fuels may cause an increase in the amount of carbon dioxide in the atmosphere.

The gases given off by engine exhaust are the oxides of nitrogen and the unburned hydrocarbons. The energy that causes these gases to react to form new compounds, comes from the sun. This reaction is called a photochemical reaction. The 'air' that is exhausted from diesel engines is also too poor to breathe, although it contains more oxygen

per cubic foot, but more particles. Ozone is a chemically reactive substance(O3)  that is sometimes used to deodorizing exhausts by oxidizing them to less objectionable odorous products before they are released to the atmosphere.

Industrial or grey smog is considered the most serious type of air pollution. Smoke and oxides that are released by burning coal and oil containing minor amounts of sulphur is the cause. The oxides of sulphur form sulphuric acid in the atmosphere, which is both toxic to life and damaging to many materials. The smoke gives the air a grey colour. Industrial smog has been known to cause air pollution disasters. One of the worst occurred in London in December of 1952. Five days of stagnant air brought about high-pressure systems and caused between 3,500 and 4,000 deaths.

Photochemical smog, also known as brown smog, is largely caused by exhaust gases. It is common in warm cities in dry areas with lots of sunshine. This type of smog can obscure vision, cause plant damage and irritate eyes.

Throughout the world the damage caused by air pollution is enormous. In money alone it represents a loss of billions of dollars each year. Many flower and vegetable crops suffer ill effects from air pollution caused by exhaust gases. Trees have been killed by pollution. Cattle have been poisoned. Air pollution causes rubber tyres on automobiles to crack and become porous. Fine buildings become shabby, their walls blackened with soot as a result of the pollution that has settled on building stones and surfaces for years.

The high cost of air pollution is strikingly illustrated in its damaging effects on the human body. Besides the unpleasantness of irritated eyes and scratchy throats, it presents a threat to the respiratory tract, contributing to a number of serious diseases. The jet airplane has revolutionized travel since about 1960. It has brought people and cultures closer together. But it has created environmental problems. Harmful chemicals sift down from the smoky trails of low-flying jets. The scream of jet engines is constantly heard by people who live near big-city airports. Jet aircraft, particularly the supersonic transport (SST) could engender stratospheric air pollution with consequent changes in climate. Jet exhaust contains water, CO2, oxides of nitrogen and particulate matter. It is speculative just how harmful these pollutants can be. For example, it is estimated that a fleet of five hundred SST's over a period of years could increase the water content of the stratosphere by 50 to 100 per cent, which could result in a rise in average temperature of the surface of the earth of about 0.2 Celsius degrees and could cause destruction of some of the stratospheric ozone that protects the earth from ultraviolet radiation. It is a fact that many people prefer air travel rather than ground or water transportation. This has prompted a critical look at safety and quality control. Contributions to air pollution is a chief concern because of this revolutionary change in public transportation around the world. The government must also establish standards for cxh.mst emissions. Thus, manufacturers are forced to develop low- pollutant engines. Contact with government agencies will give a greater insight of this subject.

An airplane needs an energy supply and an engine for propulsion that will function whenever they are needed. These internal combustion engines have discharged pollutants into the air. The combustion exhaust must he dealt with. Modification of air/fuel ratios can provide a partial solution. The problem of air pollution from airplanes involves a complex set of interactions among technical, social and economic factors.

Emission from jet aircraft, particularly on landing and take- offs, are a source of bitter complaints from nearby residents. In a few airports visibility has been dangerously restricted by paniculate emissions and photochemical smog. Airlines have a considerable expense in cleaning the obnoxious odours of unburned fuel from aircraft air conditioning systems. Most pilots prefer exhaust plumes, because aircrafts are made more visible.

Reliable data on engine exhausts are difficult to obtain because engines operate under many different conditions. Engine design plays an important role in reducing pollution emissions. One engine may emit more than a comparable engine. Older aircraft have experienced a substantial reduction in hydrocarbon, carbon monoxide and paniculate emission because the fuel is more completely burned with the installation of 'clean burner cans'.