The use of optical techniques to identify and quantify atmospheric pollutants has been focused within the past two decades.
Fourier Transform Infrared (FTIR) spectroscopy has proven to be a powerful tool for multi-component analysis of air
quality monitoring. The technique has been used for gaseous samples by extractive sampling as well as in the open-path
configuration. The present contribution has described the application of FTIR to analyze gaseous pollutants in ambient air
in detail. The study for the detection limits of the interested gas, the design of the multipass White mirror system, and the
experimental results are described. The White cell is employed to increase the absorbance relative to noise in the
absorbance spectrum by increasing the path length without proportional loss of signal. A classical least squares (CLS) fit
is used to match the scaled standards or previously measured absorption profiles to those of the observed spectrum in the
specified spectral analysis regions for simultaneous quantification of the compounds of interest, plus several other
ambient air constituents. The regions were chosen carefully to provide optimum detection of the compounds of interest
with minimum interference by other compounds. Specially, spectrum subtraction and differential absorption concepts are
introduced into FTIR data analysis. The optimal window for CO, S02, NO2, NO and CO2 would be the region at
2250-2020 cm-1, 1230-1070 cm-1, 2940-2840 cm-1, 1965-1775 cm-1, and around 668.24 cm-1 respectively. Deviations from
traditional measured results for all approaches are in 10%.