Epidemiological Analysis refers to the understanding and analysis of how different populations are affected by various risk-factors, disease, and other health outcomes. Ecosystem Health refers to the health or condition of the environment and all living organisms in that environment. That is, its susceptibility/resiliency to natural disaster and ability to sustain life defined by a number of indicators unique to the ecosystem. In conjunction, these two concepts define the health of an area and all the living organisms within it. These concepts are key to sustainability because they define the successfulness of sustainability practices. If something is being carried out in an unsustainable way it will be directly reflected in the health of the population and environment.