A simple definition for Environmental Health is that it is the study and management of environmental factors and their impact on human health, and more particularly the health of communities.

The World Health Organisation (WHO) definition is:

Environmental health addresses all the physical, chemical, and biological factors external to a person, and all the related factors impacting behaviours. It encompasses the assessment and control of those environmental factors that can potentially affect health. It is targeted towards preventing disease and creating health-supportive environments. This definition excludes behaviour not related to environment, as well as behaviour related to the social and cultural environment, and genetics. 

It is an international discipline, although practices vary from country to country, as do  the people and organisations undertaking the work. Environmental Health has been responsible for improving our life expectancy and quality of life. Practitioners have been instrumental in reducing air pollution, improving standards in housing and food safety, and mitigating infectious disease and effects of disasters.

The components that make up Environmental Health can be grouped and shown as:

Environmental Health