Large- scale and global environmental hazards to human health include climate change, stratospheric ozone depletion, loss of biodiversity changes in hydrological systems and the suppliers of freshwater, land degradation and stresses on food-producing systems.

Appreciation of this scale and type of influence on human health requires a new perspective which focuses on ecosystems and on the recognition that the foundation of long-term good health in populations rely in great part on the continued stability and functioning of biosphere’s life-supporting systems. It also brings an appreciation of the complexity on system.

Fig: Shows the Flowchart of global environmental change and health.