Use of FT-IR and UV spectrometers for monitoring multiple pollutants in the lower troposphere

Automated Fourier transform infrared (FT-IR) and ultraviolet (UV) spectrometers have been developed that provide real-time detection of multiple pollutants in the lower troposphere. In “open path” applications, the FT-IR and UV beams are transmitted through the pollution in the open air to a retromirror located up to 500 meters away. A path-averaged concentration is then determined from the total absorbance measured along the entire pathlength. Open path FT-IRs have been applied to urban areas and hazardous waste sites, but the most common application is industrial fence line monitoring of fugitive emissions of hazardous air pollutants. Open path ultraviolet (OPUV) spectrometers have also been developed for monitoring criteria pollutants such as nitrogen dioxide (NO₂), sulfur dioxide (SO ₂), and ozone, aromatic hydrocarbons, and carbonyl compounds in urban areas and along industrial fence lines. A description of each system will be given in this paper as well as areas of further development