This specialist field of study developed after the realisation that health is more widely and dramatically affected by environmental factors than previously recognized.
By far, the most important factor is fine particulate matter pollution in urban air.
Food-borne infections or infections that are water-borne (e.g. cholera and gastroenteritis caused by norovirus or campylobacteria) are typical concerns of environmental medicine, but some opinions in the fields of microbiology hold that the viruses, bacteria and fungi that they study are not within the scope of environmental medicine if the spread of infection is directly from human to human.
Its U.S. Army Research Institute of Environmental Medicine, at Natick, Massachusetts, conducts basic and applied research to determine how exposure to extreme heat, severe cold, high terrestrial altitude, military occupational tasks, physical training, deployment operations, and nutritional factors affect the health and performance of military personnel.
Research on the effect of environmental pollutants on military personnel is not part of USARIEM's mission, but is within the purview of the U.S. Army Center for Environmental Health Research at Fort Detrick, Maryland.