MAPPING AIR CONTAMINANTS INDOORS USING A PROTOTYPE COMPUTED-TOMOGRAPHY SYSTEM

Single and multiple plumes of sulphur hexafluoride were measured and m apped using a prototype open-path Fourier transform infrared spectrome ter (OP-FTIR)-computed tomography (CT) system in an indoor exposure ch amber. The OP-FTIR-CT system accurately mapped the position of concent ration peaks at different locations in the chamber, and estimated conc entrations within a range of 4-50% when compared with point samples me asured by gas chromatography with an electron capture detector. Two OP -FTIR spectrometer ray configurations, one with 100 rays and the other with 136 rays, were used to scan the chamber and reconstruct the conc entration maps. Ray configuration and time to scan the entire chamber were found to have a profound effect on the quality of the reconstruct ed maps. The ability to obtain real-time, non-invasive measurements, a nd to generate spatially and temporally resolved maps of multiple chem icals, makes the OP-FTIR-CT system a promising technique for monitorin g source emissions and evaluating exposures to air contaminants in a w orkplace. Copyright (C) 1996 British Occupational Hygiene Society.