Abstract |
The U.S. Environmental Protection Agency (EPA) evaluated a differential optical absorption spectrometer (DOAS) long path pollutant monitoring system during July and August of 1990 in Atlanta, GA. Federal Reference Method (FRM) instruments and a gas chromatograph (GC), which measure a number of gas phase air pollutants at a point, were operated concurrently as part of a larger US EPA study of ozone and its precursors in Atlanta. The DOAS was configured to measure the pollutant concentrations of SO2, NO2, O3, nitrous acid, formaldehyde, benzene, toluene and o-xylene over two open paths with 1099 m and 1824 m, respectively, between light source and light receiver. Nitric oxide (NO) and ammonia (NH3) were measured over a third path of only 143 m. In the communication the features of the DOAS system are described and results of the Atlanta, GA evaluation of the system are discussed. Comparisons are made between the DOAS open path measurements and FRM or GC measurements made concurrently at a location near the DOAS light receivers. |