A commercial Fourier transform infrared interferometer system has been installed in a van and used to make longpath absorption and single-ended emission measurements of gaseous pollutant concentrations at a variety of pollutant sources. The interferometer system is described and results of recent emission measurements of a jet engine, brick kiln, gypsum pond, and industrial stacks are presented. The system covers the infrared spectral region from 650 to 6000/cm at a maximum resolution of 0.06/cm. In the absorption mode, many gaseous pollutants can be detected at parts-per-billion levels m. over a one-kilometer path. In the emission mode, warm gases exiting industrial stacks can be detected at parts-per-million levels. The temperature of the stack gases can be determined directly from the spectra. In the jet engine measurements, acetylene, ethylene, and formaldehyde (among others) were observed; H2SO4, SO2, HF and HCl were among the species seen at the brick kiln; and remotely determined temperatures were within ten percent of instack values.