Introduction to the natural environment: dynamics of biotic components, characteristics of ecosystems, habits and niches, appreciation of nature, flora and fauna as a part of health and wellbeing. Threats to the environment: direct and indirect causes; Habitat loss, pollution, over population. Effects of climatic changes and settlement patterns on health: changing patterns of infectious diseases, global warming and spread of diseases, ozone depletion and health, chemicals and health. Mitigatory measures: Legal aspects, community participation activities and sustainable development approaches.