The prototype system works this way:
From orbiting GPS satellites, a Local Positioning System receives signals that track the movements of the person wearing the unit. Measurement devices simultaneously provide data on position, exposures and time. In the NIOSH field tests, the unit was attached to a temperature sensor and a sound-level meter that measured heat and noise at a highway paving site. The ensemble was mounted on a belt for convenience.
The data from the LPS are downloaded to a computer, which generates maps and graphs that show levels of exposure at specific work locations. The program also can filter the data specifically to show "hot spots."
NIOSH plans an additional study to test the operation of the system with a monitor designed to measure sulfur dioxide, hydrogen sulfide, carbon monoxide, carbon dioxide and other gases.