Gaseous Pollutants - Fourier Transform Infrared Spectroscopy (FTIR)

Figure: FTIR can directly measure both criteria pollutants and toxic pollutants in the ambient air.

Fourier Transform Infrared Spectroscopy (FTIR)
Fourier Transform Infrared Spectroscopy (FTIR) can detect and measure both criteria pollutants and toxic pollutants in ambient air. FTIR can directly measure more than 120 gaseous pollutants in the ambient air, such as carbon monoxide, sulfur dioxide, and ozone. FTIR technology can also measure toxic pollutants, such as toluene, benzene, and methanol. The technology is based on the fact that every gas has its own "fingerprint," or absorption spectrum. The FTIR sensor monitors the entire infrared spectrum and reads the different fingerprints of the gases present in the ambient air.

Carbon monoxide is monitored continuously by analyzers that operate on the infrared absorption principle. Ambient air is drawn into a sample chamber and a beam of infrared light is passed through it. CO absorbs infrared radiation, and any decrease in the intensity of the beam is due to the presence of CO molecules. This decrease is directly related to the concentration of CO in the air. A special detector measures the difference in the radiation between this beam and a duplicate beam passing through a reference chamber with no CO present. This difference in intensity is electronically translated into a reading of the CO present in the ambient air, measured in parts per million.