Air pollution

LEARNING OBJECTIVES

After reading Air pollution Topic You should be able to Answer following Points:-

        The atmosphere has always been a sink (place for deposition and storage) for gaseous or particulate wastes. When the amount of waste entering the  atmosphere in an area exceeds the ability of the atmosphere to disperse or degrade the pollutants, problems result. After reading this Topic, you should understand:

• Why human activities that pollute the air, combined with meteorological conditions, may exceed the natural abilities of the atmosphere to remove wastes.
• What are the major categories and sources of air pollutants
• Why air pollution problems are different in different regions.
• What acid rain is and how it is produced.
• What the environmental impacts of acid rain are and how they might be minimized.
• Why, from an environmental standpoint, the best strategies for controlling air pollution are energy efficiency and conservation.
•  What methods are useful in the collection, capture, or retention of pollutants before they enter the atmosphere.
• What air quality standards are and why they are important.
• Why the economics of air pollution is controversial and difficult.

 POLLUTION OF THE ATMOSPHERE

                        As the fastest moving fluid medium in the environment, the atmosphere has always been one of the most convenient places to dispose of unwanted materials. Ever since fire was first used by people, the atmosphere has been a sink for waste disposal. People have long recognized the existence of atmospheric pollutants, both natural pollutants and those induced by humans. Leonardo da Vinci wrote in 1550 that a blue haze formed from materials emitted into the atmosphere from plants; he had observed a natural photochemical smog whose cause is still not completely understood. The phenomenon of acid rain was first described in the seventeenth century, and by the eighteenth century it was known that smog and acid rain damaged plants in London. Beginning with the industrial revolution in the eighteenth century, air pollution became more noticeable. The word smog was probably introduced by a physician at a public health conference in 1905 to denote.poor air quality resulting from a mixture of smoke and fog. A major event in Donora, Pennsylvania, in. 1948, was responsible for increasing research on air pollution. The Donora event caused 20 deaths and 14,000 illnesses, and people recognized that meteorological conditions were an integral part of the production of dangerous smog. This view was reinforced by the 1952 London smog crisis, after which regulations to control air quality began to be formulated. Today, in the United States and in many other countries, legislation to reduce the emission of air pollutants has been successful, but much more needs to be done in many areas. Chronic exposure to high levels of air pollutants such as sulfur dioxide, ozone, carbon monoxide, particulates, and nitrogen oxides continues to contribute to illnesses that kill people in cities around the world. What are the chances that another killing air pollution event may occur again somewhere in the work Unfortunately, the chances seem all too likely given the tremendous amount of air pollution that occurring in some large cities today. For example Beijing might be a candidate; the city uses an immense amount of coal, and a cough is so pervasive among its residents that it is often called the Beijing cough. Another likely candidate is Mexico city,which has one of the worst air pollution problems found anywhere in the world today.