Abstract: A method and computer system manipulates data concerning the health of a plurality of employees, each of the employees working in at least one work location and being identifiable by an employee identification, each of the work locations being identifiable by a work location identification, substances of which at least some are potential hazardous being or having been present in at least one of the work locations, each of the substances being identifiable by a substance identification. The computer system has an updated location data base which stores location identifications and is updatable to store additional location identifications, an updatable employee identification data base which stores employee identifications, an updatable employee health data base for storing employee health data concerning each of the identified employees, and an updatable substance data base which stores substance identifications.