Lesson 1: Overview of environmental health principles
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Epidemiologic triangle model of disease causation

A common model used in public health illustrates the relationships among an agent, a host and the environment. It applies to biological, chemical and physical agents. For a disease or injury to occur, the basic elements of disease or injury causation and an adequate chain of transmission (i.e. environmental pathway) must be present. View example 1 and example 2 to learn more.

Disease occurs when an outside agent capable of causing the disease or injury meets a host that is vulnerable to the agent in an environment that allows the agent and host to interact. These basic concepts help guide the selection of health strategies to prevent health problems.

One of the key jobs for the EH professional is to intervene at any point in order to reduce the hazard to health.

(Source: CDC)

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