Open-path FTIR measurement of criteria pollutants and other ambient species in an industrial city

摘要

Abstract: Recent improvements in signal processing techniques for Open- Path FTIR (OP-FTIR) have resulted in a dramatic reduction of detection limits for infrared active chemicals including ambient species. These lower detection limits opens the open- path FTIR technology to new applications involving monitoring and analyzing ambient air in urban settings. To test application of OP-FTIR technology to urban applications, an RAM2000$+TM$/ system was used over a seven-day period to measure ambient air-quality in an urban-industrial environment. Several of the ambient species which are ozone precursors and referred to as criteria pollutants in Title I of the Clean Air Act Amendment of 1990, have poor OP-FTIR detection limits because of overlap of their infrared absorption by very strong water vapor lines. Due to the high detection limits for sulfur dioxide and nitrogen dioxide, OP- FTIR has not been the technology of choice for measuring air quality in urban environments. In the present test, we were particularly interested in the improvements in the detection limits of the criteria pollutants, ozone, carbon monoxide, sulfur dioxide and nitrogen dioxide. Improvement in these detection limits will greatly increase the suitability of using OP-FTIR for measuring urban air quality and for measurement programs relating to the USEPA tropospheric ozone- photochemistry studies. !1