What is Mass Psychogenic Illness? According to a recent History Channel Documentary, witnesses of The Salem Witch Trials actually exhibited distressing physical symptoms because they believed that they were under the spell of the supposed "witch" on the stand.
Buildings have been evacuated, with over 100 people visiting the hospital, because of complaints of environmental sickness by the occupants. Often, when such scenes are investigated, no signs of an environmental anomaly is found. Such incidents are attributed to "Mass Psychogenic Illness"; a phenomena caused by groups of people manifesting physical symptoms in reaction to their environment without any discernible physical cause. "Psychogenic Illness", on an individual level, outside of a group setting, is also a known phenomena. Both the group phenomena and the individual phenomena are caused by an unrealistic appraisal of danger. In short, an expectation of danger when there is none.
In relation to environmental tobacco smoke (ETS), it appears that no research has been done to differentiate symptoms reported from ETS exposure from those of psychogenic illness. It seems reasonable to suggest that the cause of physical symptoms in relation to exposure to ETS are psychogenic in nature in many instances. Also, it seems reasonable to suggest that those participating in retrospective epidemiological studies regarding the health effects of ETS may unconsciously select for relating ETS to instances of physical disease.
The widespread dissemination of a causative link between ETS and physical disease symptoms by government agencies and special interest groups creates an expectation of danger amongst the population. This is all that is required for psychologically sensitive individuals to exhibit physical symptoms without any real environmental danger being present.
Reference or Supporting links:
Mass psychogenic illness attributed to toxic exposure at a high school
Bioterrorism and Anthrax Anxiety
Witchcraft: The Salem Witch Trial