When the chemical released is not a type that is actively monitored by facilities/venues, recognition of a chemical incident will likely involve both the observation of something out of the ordinary and the communication of this observation to individuals capable of initiating a response. In some instances, this will result from field intelligence and investigations of threat reports of unusual or suspicious activities.
Event recognition via surveillance systems, then, involves the manifestation of health effects and the ability to recognize these effects as unusual. In particular, event recognition via surveillance systems requires syndromic surveillance and epidemiological investigations of unusual or suspicious symptoms in humans and animals.
Syndromic surveillance signs that a toxic event may be in progress include an unusually high number of people seeking medical care coincidently. Depending on the speed and severity at which the health effects manifest following exposure, a chemical incident could result in a surge of 911 calls and hospital admissions, an increase in over-the-counter sales of specific medications, and/or high volumes of Internet searches for specific symptoms.