The term environment implies all the external factors, living and non-living, material and non-material, which surround man. However, the newer concept also includes the social and economic conditions under which we live. For better understanding, environment can be divided into three components, viz. Physical (water, air, soil, housing etc.), Biological (plants and animal life including viruses, insects, rodents) and Social (customs, cultures, income, occupation etc.).

The key to man's health lies largely in his environment. In fact, much of man's ill-health can be traced to adverse environmental factors like poor housing, presence of animals, and air, water and soil pollution. Often man is responsible for the pollution of his environment through urbanization, industrialization and other human activities, which is bringing profound social and environmental changes all over the world.

Hence, to address this problem a combined multi-disciplinary programme of action is needed to achieve a healthy environment. Two of the changes needed to achieve 'Health for all' are concerned with a healthy environment and healthy life style, and require initiatives by the individual, the family and the community.