Radial plume mapping: A US EPA test method for area and fugitive source emission monitoring using optical remote sensing

This paper describes the recently developed United States Environmental Protection Agency (US EPA) test method that provides the user with unique methodologies for characterizing gaseous emissions from non-point pollutant sources. The radial plume mapping (RPM) methodology uses an open-path, path-integrated optical remote sensing (PI-ORS) system in multiple beam configurations to directly identify emission "hot spots" and measure emission fluxes. The RPM methodology has been well developed, evaluated, demonstrated, and peer reviewed. Scanning the PI-ORS system in a horizontal plane (horizontal RPM) can be used to locate hot spots of fugitive emission at ground level, while scanning in a vertical plane downwind of the area source (vertical RPM), coupled with wind measurement, can be used to measure emission fluxes. Also, scanning along a line-of-sight such as an industrial fenceline (one-dimensional RPM) can be used to profile pollutant concentrations downwind from a fugitive source. In this paper, the EPA test method is discussed, with particular reference to the RPM methodology, its applicability, limitations, and validation.