In day to day life, associations and institutions are used very commonly. Sometimes these words are used inter changeably to mean one and the same. But in Sociology these words have specific meaning

Definition of Association: According to E.S. Bogardus “Association is usually working together of people to achieve some common purpose”. According to William P. Scott “An Association refer to a formal group organised for a specialised and specifically stated pupose”.

Characteristics of Association: 

(a) Association – A Human Group: An association is formed by people. It is basically a social group. Without people there can be no association. However all groups are not associations. Because an association is basically an organized group. An unorganized ‘ group like a crowd or a mob cannot be an association.

(b) Specific Interest or Interests: An association is not only collection of individuals. But also consists of those individuals who have more or less the same interests. According those who have political interests may join political parties and those who have sports interest may join sports association and so on.

(c) Co-operative Spirit: An association is based on the cooperative spirit of its members. People work together to achieve common purpose. For example: Workers to work together on a co-operative basis in order to fulfill their objective of getting good working conditions.

(d) Organized Group: Association is not just a collection of individuals. It is an organized collections for some specific ends. Organization gives stability and proper shape to an association, organization refers to the way in which the status and roles are distributed among its members.

(e) Regulation of Relations: Every association has its own rules and regulation applicable to its members. These are called associational norms. Organization depends, on this elements of regulation. Association resorts to formal or informal means to regulate the relations of its members. For Example: Family through the institution of marriage controls the sexual behavior of its members, professional organization have formal norms to control members.

(f) Element of Stability : An association may be permanent or temporary. There are some long standing association like the political parties, trade union etc. Some associations may be purely temporary in nature, Example :Association that are established to felicitate some great writers, scientists and religious leaders. 

Oxford dictionary air pollution means “The compounds that get mixed with the atmosphere causes dangerous effects on useful plants, animals and human begin

Causes for Air pollution: Man’s activities in the name of the modernization have damaged the living species. Man’s activities are also responsible for polluting air, causing dirt, dust and smoke. The Natural disasters like volcanic eruption, forest fire and bacteria also cause air pollution. Man has created industries, vehicles, atomic energy, excessive use of Petrol and other source of energy like Coal, and different types of mining also cause air pollution.

Water Pollution: Water is essential for all living things 2/3 portion on the earth is covered by water, 97.2% of water on earth is mixed with solids and rest 2.8% only is left for drinking purpose. Water pollution occurs in three different forms. 

1. Inland pollution. 

2. Underground pollution 

3. Sea pollution.

Causes for water pollution: Water pollution is due to many factors. Factory wastes, Houses hold wastes and water from agricultural land, all these contributions to water pollution. Biological contamination like gutter water, food processing factories, skin and hide processing factories, insecticides, drugs, various chemical colours contributes to water pollution.

Noise Pollution: Intolerable sound is considered as sound pollution, because intense sound result in physical and mental stress and also irritation. Sound pollution is also result due to various activities of human begins. Intensity of sound is measured in decibels while talking usual intensity of sound is 60 decibels. 

Soil Pollution: The upper most layer of the earth is consisted of “soil” This soil layer is formed by the natural processes from millions of years. This layer supplies the necessary nutrients essential for the growth of the plants. The soil which feeds the plants is the reason for the existence of all biological system.