It's the environment, stupid! Declining ecosystem health is THE threat to health in the 21st century.

The author discusses the aspects of the health of the ecosystems, which is the most significant element of the health and wellbeing of the population. It mentions that the World Health Organization (WHO) recognizes the natural ecosystems, which is the planet's life-support systems for human being and other life forms. Moreover, it notes that human activity threatens the natural functions of the world and the ability of the ecosystems to sustain future generations can no longer be ignored.