A number of discoveries in the 19th century were important events for the understanding of communicable diseases. For example, the link between contaminated water and cholera was discovered by John Snow in 1854; the importance of hygienic handwashing before attending delivery of a baby was noted by Dr. Semmelweis in 1845; and the discovery that microorganisms (very small organisms only visible under a microscope) cause disease was made by Louis Pasteur around this time.
The period following the industrial revolution in Europe in the 19th century showed that improvements in sanitation, water supply and housing significantly reduced the occurrence of communicable diseases. The term ‘environmental health' is used to describe human health in relation to environmental factors such as these. Environmental health can be defined as the control of all the factors in a person's physical environment that have, or can have, a damaging effect on their physical, mental or social wellbeing. The issue of environmental health is now a global matter under the guidance of the United Nations (UN) through the World Health Organization.
Although hygiene and infection are vital factors in environmental health, it is also good to be aware of emerging issues such as global warming and the links between medical conditions such as cardio-vascular disease and our environment and lifestyles. Our environment is everything that surrounds us. It includes all the external influences and conditions that can affect our health, life and growth. These influences are constantly changing and the effects on our health may not be easily foreseen.